U.S. METRIC STUDY

INTERIM REPORT

ENGINEERING

STANDARDS

U.S. METRIC STUDY
ORIS

ii , - lilts of substudies of the U.S. Metric Study, while being evaluated

for the preparation of a comprehensive report to the Congress, are being

led in the interim as a series of NBS Special Publications. The titles I'lividual reports are listed below.

NBS SP345-2

NBS SP345-3

NBS SP345-4

fv I p_ Q c p J. _

o

. , . . 45-7

NBS SP345-8

NBS SP345-9

NBS SP345-iO

interniUional Standards (issued December 1970, SD

Catalog No. C 1 3. 1 0:345- 1 , Price $ 1 .25)

Federal Government: Civilian Agencies (in press)

Commercial Weights and Measures (in press)

The Manufacturing Industry (in press)

Nonmanufacturing Businesses (in press)

Education (in press)

The Consumer (in press)

International Trade (in press)

Department of Defense (in press)

A History of the Metric System Controversy in the

United States (in press)

Engineering Standards, this publication

Testimony of Nationally Representative Groups (in

press)

5: hed in August 1971

Tb'^"': ^ , :;'^ , i,..,,,,^ heep issued, and

m;- s. Government

dd oneent to a

jf order.
U.S. METRIC STUDY

INTERIM REPORT

ENGINEERING

STANDARDS

Eleventh in a series of reports prepared

for the Congress

U.S. METRIC STUDY

Daniel V. De Simone, Director

National Bureau of Standards

Special Publication 345- 1

1

UNITED STATES DEPARTMENT OF COMMERCE

Maurice H. Stans, Secretary

NATIONAL BUREAU OF STANDARDS

Lewis M. Branscomb, Director

Nat. Bur. Stand. (U.S.). Spec. Publ. 345-11. 264 pages (July 1971) CODEN: XNBSA

Issued July 1971

For sale by the Superintendent of Documents. U.S. Government Printing Office Washington, D.C.. 20402 - Price $2 Stock Number 0303-0835

(Order by SD Catalog No. C 13.10:345-1 1). Price $2.00

LETTER OF TRANSMITTAL

THE HONORABLE PRESIDENT OF THE SENATE

THE HONORABLE SPEAKER OF THE HOUSE OF

REPRESENTATIVES

SIRS:

I have the honor to present the eleventh in the series of interim reports

stemming from the U.S. Metric Study, prepared by the National Bureau of

Standards.

This Study was authorized by PubUc Law 90-472 to reduce the many uncertainties concerning the metric issue and to provide a better basis upon

which the Congress may evaluate and resolve it.

I shall make a final report to the Congress on this Study in August 1971. In the meantime, the data and opinions contained in this interim report are being evaluated by the Study team at the National Bureau of Standards. My

final report to you will reflect this evaluation.

Respectfully submitted,

Secretary of Commerce

Enclosure

iii
LETTER OF TRANSMITTAL

Honorable Maurice H. Stans

Secretary of Commerce

Dear Mr. Secretary:

I have the honor to transmit to you another interim report of the U.S. Metric Study, which is being conducted at the National Bureau of Standards at your request and in accordance with the Metric Study Act of 1 968.

The Study is exploring the subjects assigned to it with great care. We have

tried to reach every relevant sector of the society to elicit their views on the

metric issue and their estimates of the costs and benefits called for in the

Metric Study Act. Moreover, all of these sectors were given an opportunity

to testify in the extensive series of Metric Study Conferences that were held

last year. On the basis of all that we have been able to learn from these conferences,

as well as the numerous surveys and investigations, a final report will be

made to you before August 1971 for your evaluation and decision as to any

recommendations that you may wish to make to the Congress.

The attached interim report includes data and other opinions that are still being evaluated by us to determine their relationship and significance to all of the other information that has been elicited by the Study. All of these

evaluations will be reflected in the final report.

Sincerely,

Lewis M. Branscomb, Director

National Bureau of Standards

Enclosure

iv
FOREWORD

This report concerns the relationship of measurement units to engineering

standards. Although it is addressed primarily to the issues posed by Section

3 of the Metric Study Act (Public Law 90-472). it is of necessity related also

to international standards, a subject covered by a previous report.

Reports covering other substudies of the U.S. Metric Study are listed on

the inside front cover. All of these, including this report, are under evaluation. Hence, they are published without prejudice to the comprehensive re- port on the entire U.S. Metric Study, which will be sent to the Congress

by the Secretary of Commerce in August of 1971.

This report was prepared by a Metric Study task force, headed by Dr. Robert D. Stiehler and including Mr. Gustave Shapiro, Mr. Robert J. Klein,

Mr. Harry Stoub, Mr. Arthur G. Strang, and Mr. Theodore R. Young, all of

the National Bureau of Standards.

We are grateful to Mr. Frank Masterson and Mr. R. B. Belford, President

and Technical Director, respectively, of the Industrial Fasteners Institute, for permission to include their first progress report on "A Study to Develop

an Optimum Metric Fastener System." Their report, which appears as Appendix V of this volume, illustrates the manner in which innovations in en- gineering standards can be achieved.

In this as in all aspects of the U.S. Metric Study, the program has benefited from the independent judgment and thoughtful counsel of its advisory

panel and the many other organizations, groups, and committees that have

participated in the Study.

Daniel V. De Simone, Director

U.S. Metric Study

V
TABLE OF CONTENTS

Page Letters of Transmittal iii, iv Foreword v

1. Executive Summary 1 2. Summary of Conclusions and Recommendations 6

3. Purpose of Standards Survey 9

4. Scope of Standards Survey 10

5. Definitions 12

6. Function of Engineering Standards 14

7. Compatibility of Standards 17

8. Development Process for Engineering Standards 18

9. Magnitude of Standardization Effort 25

10. Measuring Units in Engineering Standards 31

11. Dimensional Specifications 34

12. Quality Specifications 43

13. Methods of Test 45

14. Descriptive Standards 47

15. I EC and Electrical Engineering Standards 48

16. ISO Recommendations 67

17. Steel 90

18. Nonferrous Metals 93

19. Plastics 96

20. Rubber 99

21. Anti-Friction Bearings 101

22. Building Construction and Materials 104

23. Pipe and Tubing 107

24. Screw Threads and Fasteners 1 1

5

25. Discussion 129

Appendices:

I. Public Law 90-472 132

II. ISO Recommendation R 1000- Rules for the Use of Units

of the International System of Units and a Selection of

the Decimal Multiples and Submultiples of the SI Units 133

III. ASTM E380-70- Metric Practice Guide 152

IV. Compatibility of Screw Threads 187

V. First Progress Report of Industrial Fasteners Institute on a Study to Develop an Optimum Metric Fastener

System 195

vi
1. EXECUTIVE SUMMARY

Public Law 90-472^ approved on August 9, 1968 authorized the Secretary

of Commerce to make a study to determine the advantages and disadvantages of increased use of the metric system in the United States. The

Congress in passing this law recognized the close relationship between en- gineering standards and measurement units and authorized a study to determine the feasibility of retaining and promoting international use of dimensional and other engineering standards based on the customary measurement

units of the United States. Section 3 of this act is specifically directed to this issue and states:

In conducting the studies and developing the recommendations required in this Act. the Secretary shall give full consideration to the advantages, disadvantages, and problems associated with possible

changes in either the system of measurement units or the related

dimensional and engineering standards currently used in the

United States, and specifically shall —

(1) investigate the extent to which substantial changes in the size,

shape, and design of important industrial products would be necessary to realize the benefits which might result from general use of

metric units of measurement in the United States;

(2) investigate the extent to which uniform and accepted engineering

standards based on the metric system of measurement units are in use in each of the fields under study and compare the extent to such

use and the utility and degree of sophistication of such metric standards with those in use in the United States; and

' See app. 1 for the full text of this law.

1
2 ENGINEERING STANDARDS

(3) recommend specific means of meeting the practical difficulties and

costs in those areas of the economy where any recommended

change in the system of measurement units and related dimensional

and engineering standards would raise significant practical difficulties or entail significant costs of conversion.

The last part of section 3, Public Law 90-472, dealing with the difficulties and costs of conversion is not within the scope of this report. Costs of conversion are considered in the report on the Manufacturing Industry, SP345-

4. The cost of issuing engineering standards based on metric measurement

units would be largely absorbed during the regular revision of the present

standards. Metric dimensional specifications for standard parts and products

would be largely based on national and international standards used in other

countries. The cost of development of new standards incorporating latest knowledge and technological capabilities would be mainly the cost of

technological improvement. On the other hand, revision of engineering stan- dards in a crash program solely to incorporate metric measurement units

could cost many millions of dollars. However, a crash program has not been

considered since it is neither necessary nor feasible. Since the passage of Public Law 90-472, the increasing worldwide use of

the metric system, which was the primary concern leading to its passage, has

now encompassed virtually all countries of the entire world. The one notable

exception to this worldwide trend is the United States. Concomitant with the

expansion in metrication has been an acceleration in the internationalization

of engineering standards on which the quality, uniformity and compatibility

of products are based. Engineering standards have served as a keystone in our domestic industrial development, as they have in other industrialized nations. These developments and the coupling of engineering standards with

product certification in Europe were presented in NBS SP345-1 on International Standards. The aspects of SP345-1 relating to engineering standards

have been included in this report.

This survey was limited to nine representative groups of engineering

standards, comprising roughly one-third of some 400 recommendations

issued by the International Electrotechnical Commission (lEC) and 1200

recommendations issued by the International Organization for Standardization (ISO) through 1969. It consisted of a comparison of over 500

lEC and ISO Recommendations with corresponding national standards

of the U.S. and six other countries. This number is less than 1 percent of the

estimated 60,000 standards issued by private and government organizations in the U.S. and voluntarily used as national standards. Nevertheless,

a study of these groups indicated trends in voluntary standardization and the

surge toward international standardization that has occurred in recent years. Company standards have not been studied since they are proprietary in nature and are affected only to the extent that they depend on national or

international standards.

The role of measurement units depends upon the category of the standard;

that is, dimensional specification, quality specification, method of test, or

descriptive standard. A survey of ISO Recommendations issued through
EXECUTIVE SUMMARY 3

1969 indicates that about 25 percent are dimensional specifications, about

15 percent are quality standards, about 45 percent are methods of test, and

about 15 percent are descriptive standards. Measurement units are important in dimensional specifications since sizes are usually simple multiples or

submultiples of the customary measurement unit employed in a particular

country. Measurement units in quality specifications and methods of test are not critical since the units serve only as a language. Differences in actual

requirements among quality specifications result from differences in en- gineering practices and not from the measurement units. Measurement units are not involved in descriptive standards. Nevertheless, the extent of incompatibility among corresponding national descriptive standards appear to be

as great as among other categories. Thus, it is the engineering practice

rather than the measurement units that determines compatibility or incompatibility of most standards. The importance of measurement units is their role in developing the engineering practice.

National standards in most countries are issued by a single standardization organization. In the U.S., voluntary standards used throughout the

country and effectively national standards are issued by about 400 organizations, exclusive of individual companies which have proprietary standards

for their products. In addition, about 6,000 local governments issue building

codes and regulations which may or may not be in agreement. Fragmentation and lack of central responsibility have led to duplication of effort and

confusion. Only a small portion of U.S. standards are coordinated by the

American National Standards Institute (ANSI) which represents the U.S.

in I EC and ISO. Participation of other organizations in ISO is through

ANSI. However, many products being standardized by ISO are not in- cluded in the present scope of ANSI or its member organizations. Private

voluntary groups in the U.S. issue about 20,000 standards, exclusive

of company and government standards, but very few standards for con- sumer goods are among them.

U.S. standards are generally not compatible with lEC and ISO Recommendations which many countries are adopting as their national standards.

The notable exceptions are standards in a few industries where there has

been active voluntary U.S. participation in the lEC or ISO technical committee. Interest in voluntary international standardization that existed early

in the century markedly decreased after World War I. Interest was revived

after World War II, but U.S. participation in ISO technical committees, subcommittees, and working groups had only reached the 50 percent level by

1970. As a result of indifference and lack of participation, U.S. practices

have not been considered in many committees. // U.S. practices are to be

reflected in international recommendations, active participation on the

drafting committees is essential.

The 1,600 I EC and ISO Recommendations issued through 1969 is about

10 percent of the estimated 15 to 20 thousand required for international commerce. Recommendations are being issued at an increasing rate. With

the increasing emphasis on international standardization, it is expected that most of the recommendations required will be drafted during the next 10

years. The U.S. cannot afford to be absentfrom the negotiations in this criti-
4

ENGINEERING STANDARDS

cat decade ofstandards development if U.S. practices and technology are to be reflected in emerging international standards.

Prior to 1967, the following measurement units were principally used in engineering standards of industrial nations:

Customary metric units

Imperial units

U.S. customary units

These units are not mutually exclusive since most Imperial and U.S. cus- tomary units are the same and some U.S. customary units are the same

as customary metric units; for example, electrical units. Customary metric

units are generally used in the U.S. for biological and chemical standards.

The current trend is to use the International System of Units (SI). Both lEC

and ISO now require SI units in all recommendations. Customary units may

also be included if desired. Future national standards which do not include

SI units are not likely to receive due consideration in the development ofin- ternational standards. This trend has been recognized by the American

Society for Testing Materials. American Society of Mechanical Engineers,

Society of Automotive Engineers, and others. These organizations now

require or recommend the inclusion of SI units in addition to customary

units in the standards which they issue. Dimensional specifications in different metric countries are incompatible

as frequently as those in countries using the inch unit for measurement.

Thus, a change to metric units does not by itself make standards compatible. The lack of compatibility among national standards of both metric

and nonmetric countries is responsible for the current movement toward in- ternational standardization. A few dimensional specifications based on the

inch and U.S. engineering practices are used internationally and have been

incorporated in lEC and ISO Recommendations. Likewise, there are a few

specifications based on metric units used throughout the world including the

U.S. For most products, however, change in engineering practices and standards is required in both metric and nonmetric countries to achieve international standardization. Thus, an opportunity is provided during such change

to make a critical review of practices incorporated in standards that have

continued because of tradition. A metrication program can provide the

psychological climate in the U.S. that is needed to effect a break from tradi- tion and reflect in standards current knowledge and technological capabilities. A metrication program could and should have as a by-product changes

in engineering practices and standards which will conserve raw materials,

improve the quality of products and reduce costs. Such benefits can be

achieved without a metrication program, but in many instances there is not

sufficient incentive to change traditional practices. A metrication program

can provide the incentive needed.

When different national standards are developed for new devices,

products, or practices, the economic cost of subsequent international standardization may be prohibitive. For example, the same electrical measure- ment units are used throughout the world. However, the possibility of inter- national standardization of the magnitudes of voltage and frequency for elec-
EXECUTIVE SUMMARY 5

trical equipment or of the practices in television communication used in dif- ferent countries is remote. In the future, standardization of new practices

and technologies should start simultaneously at the national and international levels when standardization beyond the company level is essential.

Finally, three questions were posed at the start of the survey. They may

be answered as follows:

Q. To what extent are U.S. standards incompatible with international

standards because of the differences in measurement units?

A. Only dimensional specifications comprising about 25 percent of en- gineering standards are incompatible because of measurement units. However, not all dimensional specifications are incompatible and more than a change in measurement units is required to make incompatible dimensional specifications compatible.

Q. Is it feasible to retain and promote U.S. standards without a change

in our measurement units?

A. It is still possible, but it is becoming more and more difficult, to promote U.S. standards having only customary units. Promotion of

U.S. standards internationally is greatly facilitated when the standard permits easy use in metric countries. Recent actions by several

standardizing organizations to include measurement units of the In- ternational System of Units result from a recognition of this trend. Q. Is the nature of our measurement units a significant factor influencing U.S. effectiveness in international standards negotiation?

A. Yes. Efforts devoted to defending the use of U.S. customary units or to persuading the incorporation of dual units or sizes in international standards frequently makes negotiations on important fea- tures of U.S. practices ineffectual.
2. SUMMARY OF CONCLUSIONS

AND RECOMMENDATIONS

2.1 CONCLUSIONS

( 1 ) Engineering standards and measurement units are separate but related

items, (sees. 6 and 1 1

)

(2) The compatibility or incompatibility of engineering standards in dif- ferent countries depends primarily on the engineering practices rather than

the measurement units; a change in units without a change in engineering

practices will not resolve present incompatibilities among standards, (sees.

7, 8.5, and 14)

(3) Measurement units are important in engineering standards when a series of product sizes, such as screw threads, are based on simple multiples or submultiples of the customary measurement units employed in a particular

country. On the other hand, sizes based on the same units are frequently not

the same in different countries, (sec. 11.1)

(4) Dimensional specifications for standard products, in which measure- ments units are critical, comprise about one-fourth of engineering standards,

(sees. 6 and 10)

(5) In most engineering standards, measurement units serve only as a lan- guage; descriptive standards generally do not include units, (sees. 6, 10, and

13)

(6) Many engineering standards in the U.S. employ customary metric

units, particularly standards for biological and chemical materials, (sees. 13 and 17)

(7) In the U.S. and other countries and in international standardization,

the current trend is to include or use the International System of Units (SI)

innewandrevisedstandards. (sees. lOand 13)

6
SUMMARY OF CONCLUSIONS AND RECOMMENDATIONS 7

(8) The International Electrotechnical Commission and the International

Organization for Standardization are the two worldwide voluntary organizations concerned with standardization of engineering practices, (sec. 8.3)

(9) The U.S. through the American National Standards Institute participates in about 50 percent of the I EC and ISO groups developing international recommendations and standards, (sec. 8.4)

(10) The compatibility of U.S. standards with lEC and ISO Recommendations is related to the degree of U.S. participation in the group drafting the

recommendations; but approval of an lEC or ISO Recommendation by

ANSI does not necessarily imply compatibility with corresponding U.S.

standards, (sees. 8.3, 8.4, and 17 to 24)

(11) U.S. standards that are or can be readily used in metric countries are more likely to receive due consideration in developing the lEC or ISO

Recommendations, (sees. 13, 19, and 20)

(12) Some dimensional specifications based on the inch unit that are in use throughout the world are lEC or ISO Recommendations, (sees. 15.4,

23.2, 24.2, and 24.10)

(13) It is becoming increasingly more difficult to have inch-based dimensional specifications approved as lEC or ISO Recommendations, (sees. 10

and 1 1

)

(14) The use of standard products whose dimensions are based on SI

units is increasing within the U.S., particularly by companies manufacturing

in several countries, (sees. 21.1, 24.7, and 24. 1 5)

(15) Metrication without guidance can lead to a doubling in number of

sizes and an economy burdened indefinitely with both inch-based and mil- limeter-based sizes, (sees. 24.7 and 24. 15)

(16) Advantage should be taken in any increased usage of metric-based

standard parts and products to effect through international standardization a reduction in the number of sizes and to incorporate latest knowledge and

technology in establishing the international standards, (sees. 11.3, 23.3,

24.10, and 24.15)

(17) A by-product of conversion to metric-based parts and products can

be conservation of materials and improved quality specifications, particularly in those instances where traditional practices have hindered change,

(sees. 23.3 and 24.15)

(18) Currently, about 400 voluntary and government organizations issue

engineering standards used throughout the U.S. which has resulted in duplication of effort and confusion; this uncoordinated system is not conducive to

efficient functioning particularly at the international level, (sec. 8.2)

(19) There is an urgent need for review at both the domestic and international levels of the administrative process involved in the issuance of standards to handle the increasing rate of standards development, (sec. 9.3)

(20) The critical decade in international standardization has begun; failure to act promptly is likely to be detrimental to U.S. foreign trade of the future,

(sec. 9.3)

(2 1 ) Standardization of new practices and technologies that require standardization beyond the company level should begin simultaneously at the
8 ENGINEERING STANDARDS

national and international levels if the prohibitive costs on international

standardization after national practices are well established are to be

avoided, (sec. 15.4)

2.2 RECOMMENDATIONS

The findings of this survey have led to the following recommendations:

( 1 ) That the highest priority be given to reviewing and revising engineering standards in any metrication program, be it evolutionary, planned or mandatory.

(2) That international standardization be fostered in order to achieve the

greatest economic benefit.

(3) That advantage be taken in any metrication program to effect through

international standardization a reduction in number of product sizes, conservation of materials, and an improvement of product quality, by incorporating

latest knowledge and technology, particularly in those instances where tradi- tional practices have hindered change.

(4) That the use of SI units, either alone or with customary units, in all U.S. standards be promoted in order to foster their acceptance internationally and that standards be drafted in such form to permit easy use in metric countries.

(5) That standardization of new practices and technologies which require

standardization beyond the company level, begin at the international level in order to avoid the prohibitive cost of international standardization after national practices are well established.

(6) That, except for the inclusion of SI units, no change in domestic stan- dards be made when the cost of implementing the change would be prohibitive compared to the benefits, such as in the case of the standard for railway

gage of existing railroads.

(7) That special attention be given to the administrative process of

standardization in order to assure adequate U.S. participation in groups

drafting standards at the international level, and to the development and

issuance of national standards required by the consumer, industry, and

government.
3. PURPOSE OF STANDARDS SURVEY

The intimate relationship between measurement units and engineering

standards was recognized by the Congress in drafting Public Law 90-472 by

the following provisions in sections 1 and 3, respectively:

"That the Secretary of Commerce is hereby authorized ... to study the

feasibility of retaining and promoting by international use of

dimensional and other engineering standards based on the

customary measurement units of the United States . . . ."

"In conducting the studies and developing the recommendations required in

this act, the Secretary shall give full consideration to the advantages, disadvantages, and problems associated with possible

changes in either the system of measurement units or the related

dimensional and engineering standards currently used in the

United States . . . As a consequence of these provisions, a Standards Survey was included as one part of the overall Metric Study initiated under Public Law 90-472 to provide answers to the following questions:

(1) To what extent are U.S. standards incompatible with international

standards because of the differences in measurement units?

(2) Is it feasible to retain and promote U.S. standards internationally

without a change in our measurement units?

(3) Is the nature of our measurement units a significant factor influencing U.S. effectiveness in international standards negotiations?

In order to obtain meaningful answers to these questions, it was important to determine the role of measurement units in engineering standards.

9
4. SCOPE OF STANDARDS SURVEY

The many thousands of engineering standards in existence in the United

States and in other countries and the hmited financial resources available to conduct the Survey made a limitation in the scope necessary. Therefore, the

Survey was restricted to the international recommendations issued by the

International Organization for Standardization (ISO) and the International

Electrotechnical Commission (I EC), the two voluntary standardization or- ganizations that have worldwide membership. These recommendations are

indicative of current trends toward harmonization of national standards.

Even a comparison of the approximately 1,200 ISO Recommendations

and 400 lEC Recommendations with national standards of various countries was too great a task with the available resources. Accordingly, the Survey was further restricted to the following nine groups of standards:

Steel

Nonferrous metals

Plastics

Rubber

Pipe and tubing

Antifriction bearings

Threaded fasteners

Electrical and electronic components and equipment

Building construction and materials

These nine groups are representative of standards for basic engineering

materials, components, and products. Conclusions and recommendations in this report are based on a survey of engineering standards in these nine

groups.

10
SCOPE OF STANDARDS SURVEY 11

This report does not attempt to assess the cost of conversion or to study means of meeting the practical difficulties and costs involved in converting

manufacture to engineering standards based on metric measurement units

mentioned in item (3) of section 3 of Public Law 90-472. Other reports deal

with costs involved in conversion, particularly SP345-4 on the Manufacturing Industry. Cost of issuing engineering standards based on metric meas- urement units would be largely absorbed during the regular revision of the

present standards. Metric dimensional specifications for standard parts and

products would be largely based on national and international standards

used in other countries. The cost of development of new standards incorporating latest knowledge and technological capabilities would be mainly the cost of technological improvement. A crash program solely to incorporate

metric measurement units in engineering standards would cost many mil- lions of dollars. Such a program is not feasible and therefore is not considered as an alternative in the U.S. Metric Study.

422-764 OL - 71 - 2
5. DEFINITIONS

5.1 ENGINEERING PRACTICE

A way in which things are made or done technically, such as in characterizing, constructing, describing, designing, dimensioning, drawing, inspecting, manufacturing, measuring, prescribing, sampling, servicing, testing, or using a product, or a thing made to have prescribed attributes.

5.2 ENGINEERING STANDARD

An engineering practice established by authority or mutual agreement and

described in a document to assure dimensional compatibility, quality of

product, uniformity of evaluation procedures, or uniformity of engineering

language. Examples are documents prescribing screw thread dimensions,

chemical composition and mechanical properties of steel, dress sizes, safety

standards for motor vehicles, method of test for sulfur in oil, and codes for highway signs.

5.3 MEASUREMENT STANDARD

A device or physical phenomenon which is used to define or determine some characteristic of a thing in terms of a unit of measurement established

by authority. Examples are gage blocks, weights, thermometers, and mean

solar day.

12
DEFINITIONS 13

5.4 INTERNATIONAL SYSTEM OF UNITS (SI)

The coherent system of units based upon and including the meter (length),

kilogram (mass), second (time), kelvin (temperature), ampere (electric current), and candela (luminous intensity) as established by the General Conference on Weights and Measures in 1960 under the Treaty of the Meter.

The radian (plane angle) and the steradian (solid angle) are supplementary

units of the system. All other units are derived from these eight units.

5.5 CUSTOMARY UNITS OF MEASUREMENT

The units most commonly used in trade within a country. In metric countries, they are the units in use prior to the adoption of the International

System of Units. In the United States, they are units related to the yard and

pound but are frequently referred to as the "inch-pound system."

5.6 METRICATION

Any act tending to increase the use of the metric system (SI), whether it be

increased use of metric units or of engineering standards that are based on

such units.
6. FUNCTION OF ENGINEERING

STANDARDS

The function of an engineering standard varies from one to another, but it

is one or more of the following:

6.1 DIMENSIONAL SPECIFICATIONS

Standards of this type are essential either for the product or system to function or for interchangeability of parts. For example, the distance

between rails (gage) and between wheels in a railroad must conform to a standard in order to have the railroad function. On the other hand, standards

aimed toward interchangeability of parts may be applicable to production of an entire industry or of a single company. For instance, automobile tires are interchangeable on an industry-wide level; whereas, the wheels on which

they are mounted are generally interchangeable only on vehicles of the same make produced by a single company since the number and spacing of the

bolt holes in the wheels have not been standardized for the industry. Sizes in dimensional specifications are usually simple multiples or submultiples of

the measurement unit. As a consequence, the system of units is generally an

importantfactor in such standards.

6.2 QUALITY SPECIFICATIONS

The purpose of these standards is to assure ( 1) a quality level adequate for the required service and (2) uniformity in quality from one item to another.

Quality level is a dominant factor in safety standards; for example, seat belt

14
FUNCTION OF ENGINEERING STANDARDS 15

Standards and specifications for steel forgings for pressure vessel shells. Measurement units serve as a language in quality specifications, and hence

are not critical. Different systems of units in quality specifications create problems analogous to those encountered in standards expressed in different

written languages. Incompatibilities in requirements among quality specifications result from differences in engineering practices and not from the

measurement units. ,

6.3 METHODS OF TEST

These standards provide a common basis for evaluating materials and

products. They establish standardized procedures for determining critical dimensions or product quality, and are essential for determining compliance

of a product with a specification. A typical method is mechanical testing of

steel products. Methods of test can generally be based on any measurement

units, and the results of test can be transformed from one system of units to another. Thus, the units in methods of test, as in quality specifications, serve

as a language. Incompatibilities can result from the restrictive way in which

a method is written or from differences in engineering practices.

6.4 DESCRIPTIVE STANDARDS

These standards comprise those standardized engineering practices which

do not involve units of measurement. They include codes, symbols, sampling

and other statistical practices, terminology, format for engineering drawings,

and other descriptive engineering practices. Typical examples are sample

size to estimate the average quality of a lot or process, color coding of elec- tronic components, code for highway signs, identification colors for pipes

conveying gases and liquids, international code for the abbreviation of titles of periodicals, and nuclear energy glossary. Although measurement units are not involved, descriptive standards may be as incompatible as dimensional

specifications. For example, the practice of keeping to the left side of the

roadway in some countries and to the right side in others is not amenable to a compromise or compatible solution. Other than live with both, the only

resolution is for one group of countries to change their practice.

6.5 MULTIFUNCTIONAL STANDARDS

Some standards for products include dimensional requirements, quality

requirements, methods of test and descriptive provisions. More commonly,

separate standards are issued for methods of test and descriptive standards

since a single such standard is generally applicable to a broad class or group

of materials or products. These standards become part of material or product

specifications by reference. Similarly, a quality specification is frequently is- sued for a material used in a wide range of products; for example, a quality
16 ENGINEERING STANDARDS

specification for a certain grade of cement or steel. Such specifications are then referenced in the specifications for products in which these materials

are required. Even a dimensional specification such as screw threads is referenced in specifications for numerous fasteners and other products.

Thus, the function of any particular standard depends on its scope. Measurement units are not vital in most standards. In dimensional specifications,

measurement units play a language role. In addition, they usually become

one of the factors incorporated into the practice of the engineering standard.

This dual role accounts for their importance in most dimensional

specifications.
7. COMPATIBILITY OF STANDARDS

Two standards are compatible when the same engineering practice is prescribed. It is not necessary that the same measuring units and written

words be used. For example, certain pipe standards in many countries are compatible even though each country uses its customary units and written

language in the standard. On the other hand, standards for pipe thread in England and the U.S. are not compatible even though they are both expressed

in the same measurement unit and written language. Thus, it is the engineering practice rather than the measurement units which determine compatibility or incompatibility ofstandards, and a change in units without a change

in engineering practice will not resolve present incompatibilities among

standards. The importance of measurement units is their role in developing

the engineering practice. In the past, most products made in a series of sizes

conformed to whole numbers, multiples of binary fractions or simple

decimals in the system of units used. For example, steel bar and rod are usually made in the U.S. in increments of 1/16 inch in the smaller sizes, 1/8

inch in the intermediate sizes, and 1/4 inch in the larger sizes. In metric

countries, the increments are 1 , 2, or 5 millimeters. As a consequence, the

two standards are not compatible. In order to resolve this problem and to

select sizes on a rational basis, the tendency today is to use the rational

system proposed by Charles Renard in 1879 for establishing sizes. This

system known as preferred numbers is based on a geometrical (rather than

arithmetical) progression for selecting sizes. For applications requiring an

arithmetical progression for sizes, for example in building construction, the

modular system is being used in standards. Whether preferred numbers or modules are used for determining sizes, a choice must be made for the base

size. A base module of 100 millimeters is generally not compatible with one

of 4 inches (101.6 mm). Likewise, a preferred number series based on U.S.

customary units is not compatible with one based on SI units unless the dif- ference of 1.6 percent can be tolerated. In a few instances, worldwide agree- ment exists on sizes, based on either U.S. customary or metric units. For

most products, agreement does not exist and the practices in many or all countries must be changed to achieve compatibility ofsizes.

17
8. DEVELOPMENT PROCESS FOR

ENGINEERING STANDARDS

Engineering standards are developed and promulgated at three levels; namely, by a single organization, by a national organization, and by an inter- national organization. The degree of coordination increases as a standard

progresses from the single to the national to the international organization.

8.1 STANDARDS ISSUED BY A SINGLE

ORGANIZATION

These standards which are issued by a local government or a single company, either a producer or consumer, are generally poorly coordinated. They

include local building codes, company purchase specifications, and producers specifications for the products he sells or uses in his manufacturing

process. The objective of these standards is to provide interchangeability of

parts and/or to obtain a quality level in products purchased or sold. Codes is- sued by some 6,000 local governments prescribe minimum quality levels for building construction and repair. Insofar as a standard issued by a single or- ganization is incompatible with other standards for the same product, it restricts trade. When there are numerous company standards instead of an

industry or national standard, similar parts for products of different companies (e.g., wheels on automobiles of different makes) are not interchangeable. Hence the demand for a replacement part is inversely related to the

number of different standards for the part. As a consequence, the market for a part made to a particular company standard may be too small to attract manufacture by anyone other than that company. Thus, company standards

18
DEVELOPMENT PROCESS FOR ENGINEERING STANDARDS IQ

may foster proprietary interests and reduce the availability of replacement

parts to the consumer. In some instances replacements for proprietary parts

must be ordered from the manufacturer with all the attendant delays of such

purchases.

8.2 NATIONAL STANDARDS

Standards used throughout a country and issued by an organized group

within the country are national standards. In Russia and a few other countries, they are issued by the government and are mandatory. In the U.S. and

most other countries, only regulatory standards are mandatory. Most en- gineering standards are voluntary. In most countries, a single group or or- ganization issues most or all national standards. In the U.S., about 400 or- ganized groups issue standards that are recognized nationally. They include

TABLE 1 . Sources of American National Standards

Approved by American National Standards Institute

Member Organizations:

American Association of Textile Chemists and Colorists American Concrete Institute American Dental Association American Gear Manufacturers Association American Institute of Architects American Petroleum Institute American Society of Civil Engineers

American Society of Heating. Refrigerating, and Air-Conditioning Engineers

American Society of Mechanical Engineers

American Society for Quality Control American Society for Testing and Materials American Water Works Association American Welding Society

Anti-Friction Bearing Manufacturers Association Architectural Aluminum Manufacturers

Association Association of American Railroads

Builders Hardware Manufacturers Association Compressed Gas Association Conveyor Equipment Manufacturers Association Diamond Core Drill Manufacturers Association Edison Electric Institute Electronic Industries Association Federation of Societies for Paint Technology

Illuminating Engineering Society

Institute of Electrical and Electronic Engineers

Institute of Traffic Engineers

Insulated Power Cable Engineers Association Mechanical Power Transmission Association National Electrical Manufacturers Association National Fire Protection Association

National Fluid Power Association

Resistance Welder Manufacturers Association Society of Automotive Engineers

Technical Association of the Pulp and

Paper Industry Underwriters' Laboratories Government Organizations:

American Association of State Highway

Officials Bureau of Mines. Department of Interior Department of Defense Department of Health, Education, and Welfare General Services Administration

Interstate Commerce Commission

National Bureau of Standards, Department

of Commerce

Foreign and International Organizations:

Institute of Petroleum (London)

International Electrotechnical Commission

International Organization for Standardization
20 ENGINEERING STANDARDS

the government, organizations of government officials such as the American

Association of State Highway Officials, the Association of Official Analytical Chemists and National Association of State Purchasing Officials, and

private voluntary organizations such as the American National Standards

Institute, American Pharmaceutical Association, American Society for Testing and Materials, American Society of Mechanical Engineers, Institute of Electrical and Electronic Engineers, Society of Automotive Engineers, in- dustrial trade associations, etc. The degree of coordination depends on the

organization issuing the standard. American National Standards issued by

the American National Standards Institute (ANSI) probably represent the

greatest degree of coordination among the voluntary standards and are recognized internationally as our national standards. Most of these stan- dards are developed by 35 member organizations of ANSI and seven government organizations listed in table 1 , but only a small portion of stan- dards developed by these organizations have thus far become American National Standards. ANSI does not issue standards for food, drugs, and other

biological materials. National standards may restrict trade, but they tend to be less restrictive than standards issued by a single organization. Although

there is no deliberate attempt to do so, measurement units customarily used

within a country and the sizes of products based on the measurement system

can serve in national standards as trade restrictions in international commerce.

8.3 INTERNATIONAL STANDARDS

International standardization began informally when immigrants to the

United States continued to use the engineering practices that they brought

with them. The first formal movement began in 1882 when a small group of

workers in experimental engineering held an international conference in Munich to stimulate standardization of testing procedures. This movement

rapidly expanded and larger meetings were held in 1884 (Dresden), 1886

(Berlin), 1888 (Munich), 1893 (Vienna), and 1895 (Zurich). At the Zurich

Congress, the International Association for Testing Materials (lATM) was

formally organized with headquarters in Vienna, Austria. Many members of

I ATM were in the United States. They organized the American Section of

I ATM on June 16, 1898, which was incorporated in March 1902 under the name of American Society for Testing Materials (ASTM).- During this period interest also developed in international standardization in the field of

electricity, and a resolution at the 1904 meeting of the International Electrical Congress held in St. Louis led to the formation of the International Electrotechnical Commission (lEC) in 1906 with headquarters in London. In- stead of individual memberships as in I ATM, the members of I EC were national committees in participating countries. The U.S. National Committee

for lEC was founded in 1 907.

- Name was changed in 1 96 1 to American Society for Testing and Materials.
DEVELOPMENT PROCESS FOR ENGINEERING STANDARDS 21

Interest in international standardization within the United States reached

a peak just before World War 1. At that time, 623 or over 20 percent of the

2,849 members of lATM were in the U.S.; Germany was second with 466

members. To promote the international use of ASTM Standards, twenty

specifications for steel products were published in the English, French, German and Spanish languages by ASTM in 1913. Subsequently, the U.S. Department of Commerce translated ASTM Standards having an important

bearing on export trade and distributed them to Consular Offices throughout

the world.

U.S. interest in international standardization continued during and after World War I, but it decreased markedly after lATM ceased to function in 1915. Neither the new I ATM nor the International Standards Association

(ISA), both of which were formed in 1926, revived the interest in international standardization that existed prior to World War I. Both the new

I ATM and ISA ceased to function in World War II. The need for international standardization was recognized by the Allied

Nations. In 1944. they formed the United Nations Standards Coordinating

Committee to coordinate standards for products produced in the various

countries. The need for continuing the work of the committee after the war

led to the establishment of the International Organization for StandardizaTABLE 2. Countries Part

Standardizatio

Country lEC ISC Argentina X

Australia X X

Austria X X

Belgium X X

Brazil X X

Bulgaria X X

Canada X X

Ceylon X

Chile X

China X

Columbia X

Cuba X X

Czechoslovakia X X

Denmark X X

Finland X X

France X X

Germany X X

Ghana X

Greece X X

Hungary X X

India X X

Indonesia X X

X X

Iraq X

Ireland X

Israel X X

Italy X X

Japan X X

cipating in International

: lEC and ISO

Coiinuy lEC 'iSO Korea (North) X X

Korea (South) X X

Lebanon X

Malaysia X

Mexico X

Morocco X

Netherlands X X

New Zealand X

Norway X X

Pakistan X X

Peru X

Philippines X

Poland X X

Portugal X X

Romania X X

Singapore X

South Africa X X

Spain X X

Sweden X X

Switzerland X X

Thailand X

Turkey X X

USSR X X

United Arab Republic X X

United Kingdom X X

United States X X

Venezuela X X

Yugoslavia X X
22 ENGINEERING STANDARDS

tion (ISO) in 1946. lEC, which was able to survive both World Wars 1 and

II. affiliated with ISO in 1947 but retained its autonomy. These two voluntary organizations have become predominant in international standardization.

Participating countries in these organizations are listed in table 2. There are

also regional organizations. The Pan American Standards Commission (COPANT) operates in the Western Hemisphere. The International Commission on Rules for the Approval of Electrical Equipment (CEE), the

Economic Commission for Europe (ECE). and the Committee for the Coordination of European Standards in the Electrical Field (CENEL) are con- cerned with standardization in Europe. The U.S. is represented in lEC, ISO

and COPANT by the American National Standards Institute. Because of the worldwide representation in lEC and ISO, their Recommendations reflect the greatest degree of coordination. The use of I EC and

ISO Recommendations is voluntary, but many countries are adopting them

as their national standards. I EC and ISO Recommendations reflect the en- gineering practices of the nations that participate in drafting them. As a con- sequence, a nation which does not participate at the drafting stage may be at a disadvantage in international trade because adequate consideration was

not given to its engineering practices during the deliberations leading to the

recommendations.

8.4 TECHNICAL COMMITTEES

Both national and international organizations engaged in standardization

operate through technical committees. A committee is responsible for stan- dards in a particular field indicated by its title; for example, Committee on

Steel. ASTM, the largest voluntary standardizing organization in the U.S.,

has 1 15 technical committees. At the international level, there are 70 technical committees in lEC and 139 in ISO. Technical committees may have subordinate organizational units such as subcommittees, sections, working

groups, task groups, etc. The lowest unit generally develops the initial draft of a standard and has the greatest influence in selecting the particular practice that is standardized. Therefore, participation is necessary at both the

committee and lower organizational levels to have adequate consideration

given to a practice of particular interest. Nationally, it requires active participation by a company or other organization. Internationally, participation

is even more important since engineering practices generally vary among

countries more than among companies within a country. Yet, the United

States has been poorly represented as evidenced by the following participation in ISO:

Total U.S. participation

Organizational unit number

Number Percent

Technical committee 139 96 69 Subcommittee 305 196 64 Working groups 566 214 36

All units 1010 506 50
DEVELOPMENT PROCESS FOR ENGINEERING STANDARDS 23

Participation in lEC cannot be readily ascertained since all documents,

except working group documents, are automatically circulated to each National Committee. However, members of the U.S. National Committee have

made an estimate of 95 percent participation in technical committees and

subcommittees. At the working group level, participation is estimated to be

50 percent or less. Effective representation is probably less than indicated by these figures

since U.S. delegates do not attend many meetings of bodies on which there

is nominal participation. Continuity in representation by competent

delegates who serve for extended periods of time is essential to make participation effective. Lack of participation in these international meetings

equals or exceeds measurement units as a factor responsible for the in- compatibility of U.S. standards and many international recommendations.

8.5 PROCESS FOR ESTABLISHING ENGINEERING

STANDARDS

Wherever a multiplicity of practices is both possible and likely to occur, group cooperation for the achievement of some desirable social goal may

require the acceptance, by the members of the group, of some joint decision

to use one or a limited number of the possible alternatives. When the activities involved relate to social behavior the agreements (standards) are called

laws. When related to religious behavior they are canons. And when related

to manufacturing, testing, measurement practices and conventions, properties and performance of materials, or to the performance or characteristics

of things, they are variously called standards of practice, code regulations, or conventions. All of these latter are commonly lumped together under the

term "engineering standards."

The pattern of standards development has evolved into two main classes. At the industry level, standards are developed by materials and parts producers and device assemblers and presented to the ultimate consumer in the

marketplace. Alternatively, the standards may be promulgated as procurement specifications by a buyer that is sufficiently large and important to have

the standards met — for example, the Federal Government. Clearly, the two

methods of arriving at standards — one initiated by the supplier and the other

by the buyer— will often yield different decisions, with differing sets of advantages and disadvantages. A third class, where the ultimate consumer

would set standards, has not emerged, probably because of lack of organization and competence among the body of consumers. Where small groups which have developed standards seek to get together

to form a larger aggregate of cooperation, they must resolve the differences

in standards to arrive at a new set for the enlarged group. This process is called coordination or harmonization of standards. If the standard is established, first off, for the enlarged group, the costly waste motions of

standard setting followed by later change and readjustment within the groups

is eliminated.
24 ENGINEERING STANDARDS

Coordination or harmonization of standards at the national or international level proceeds in a similar manner. A draft is presented by a single or- ganization or nation to the appropriate committee or task group. After study,

modifications are made and a proposal or tentative standard is drafted for ap- proval by letter ballot of the group. Disapprovals by members of the group

are considered at subsequent meetings. After a consensus is reached, the

drafting group submits the document to the full technical committee for approval. Again, a letter ballot is taken and disapprovals are referred back to the drafting group for consideration. If possible, modifications are made to resolve the objections. If the modifications are substantial, the document is again balloted. When a consensus is reached in the committee, the document

is submitted to the parent organization for further processing.

In the case of ISO, the document progresses from a Draft Proposal to a Draft Recommendation when the technical committee approves it. The

Draft Recommendation is submitted to all member countries for letter ballot. Disapprovals and comments are referred back to the technical committee for consideration. When a consensus has finally been reached, the document is issued as a Recommendation. An ISO Recommendation may

subsequently become an ISO Standard, but thus far no standard has been

issued.

lEC functions differently than ISO since all National Committees auto- matically receive all committee drafts of I EC Recommendations for comment. When a final draft is prepared, it is circulated for letter ballot of National Committees under a "six-month's rule." Modifications to reconcile

objections are circulated for letter ballot under a "two-month's procedure."

An lEC Recommendation is issued on the basis of the best consensus. Obviously, the process for establishing engineering standards takes a long

time. A national standard generally requires 2 or more years to process. The

process for an international recommendation takes about 6 years, two to three times longer than that for a national standard. Minor amendments or

revisions can be processed somewhat faster, but a substantial revision takes

as long to process as the original document.

Thus, once an lEC or ISO Recommendation is issued, it is in effect for a long period before a change can be made. As the recommendation becomes

incorporated in ,more and more national standards, a substantial change in the recommendation becomes more difficult to make. As a consequence, any

particular industry in the U.S. which does not participate in the drafting of

the original recommendation discovers that it is too late to effect a change

after a recommendation has been issued. When U.S. practices differ markedly from those in the international recommendations, the industry

concerned may be adversely affected in international trade.
9. MAGNITUDE OF STANDARDIZATION

EFFORT

9.1 UNITED STATES

Except for the few regulatory standards issued by some government agency, the use of engineering standards in the U.S. is voluntary. Their effective- ness depends on the extent to which the voluntary standards are included in procurement contracts. Even though voluntary, the need for standards has

long been recognized, at both the national and international level. To this end, many have voluntarily contributed the necessary technical knowledge

and financial support. Yet, there has never been a single organization in the

U.S. covering the entire gamut of engineering standards. Standardization activities have grown without coordination and have been fragmented among

more than 400 standardizing groups.' Only a small portion of national

standards issued by about 40 member organizations are coordinated by the

American National Standards Institute. Standards for foods, drugs, and

other biological materials are not included in the scope of ANSI or its member organizations.

Fragmentation and lack of central responsibility have led to duplication of

effort and confusion. For example, standards for steel pipe are issued by

three Federal Agencies and five private organizations. Some of these stan- dards are essentially duplicates, others differ to some extent. Numerous

standards for essentially the same product can be costly, particularly when

adjustments in the manufacturing process must be made to satisfy the

requirements of slightly different specifications. Further, the multiplicity of

3 See Directory of United States Standardization Activities. National Bureau of Standards

Miscellaneous Publication 288.

25
26 ENGINEERING STANDARDS

Standards for a particular product leads to opposition of many producers to standards and to objections by consumers to higher prices and restricted sources for replacement parts.

In spite of fragmentation and duplication, voluntary organizations in the

United States have developed about 20,000 national standards. In the field of materials alone, ASTM has issued over 4,000 standards. However, these

20,000 standards include only those of interest to the members and u/hose

development the members have been willing to finance. The Department of

Defense has issued almost 35,000 specifications or standards, in addition to the 5,000 Federal specifications issued by the General Services Administration, in order to function. This number, which is more than twice the number

of standards issued by private organizations, includes many for consumer

goods, such as food and clothing, as well as those for electronic equipment

and other products involving advanced technology. As a consequence, many

Federal and military specifications are effectively national standards, particularly for end products used by the ultimate consumer. Very few such

standards issued by private organizations are in existence. The 1970 ANSI

Catalog lists only 125 standards for consumer goods and most of these pertain to items used in home construction. The consumer benefits from other

standards such as standard bearings, fasteners, and other parts used in the

manufacture of consumer products. Nevertheless, a large void remains in standards for consumer goods.

The small number of standards for consumer goods probably stems from

the lack of representation of the ultimate consumer on most committees.

Standards development is costly and consumers are not directly able to send

knowledgeable representatives. For example, the development of national

standards for color television employed 10,000,000 engineering man-hours.

Small companies and consumer organizations generally cannot afford to participate actively on the numerous committees of interest to them. Thus, the

most active members on committees are representatives of large consumers,

producers and the government since these organizations can support the

necessary laboratory and investigative work needed to establish standards.

The interests of the individual consumer are indirectly represented to a

limited extent by government involvement in standards development and ul- timately by the play of the marketplace. Recent trends toward consumer

awareness and participation indicate that the existing play of the marketplace is not enough. Either a very large organization of consumers that can have competent representation on committees or greater government in- volvement may be necessary to represent fully the consumer's interest.

The upper limit for the number of national standards required in the

civilian economy would appear to be 40,000 since many specifications used

by the Department of Defense are for items used by the military only.

Although the 20,000 standards issued by voluntary organizations have many

duplications, this number would appear to be the lower limit since these or- ganizations have not yet established standards for many items, particularly for consumer goods.
MAGNITUDE OF STANDARDIZATION 27

9.2 OTHER COUNTRIES

In many countries a single organization issues standards. In other countries, one organization issues standards for all materials and products, except

food, drugs and biological materials. In either case, they are supported to some extent by their governments and are officially recognized. Thus, the

general practice is to have one or a very small number of organizations

responsible for national standards. The approximate number of standards is- sued by some of these national organizations are as follows:

Association Francaise de Normalization *7,000

British Standards Institution *5,500

Deutschen Normenausschuss 11 ,000 Ente Nazionale Itaiiano di Unificazone *6,000

Gosudarstvenny j Komitet Standartov, USSR 13,000

Indian Standards Institution 5,000

Japanese Standards Association *7,000

*Does not include standards for food, drugs, and biological materials.

India, a developing nation, expects to have over 10,000 standards at the

completion of the fourth plan. The number of standards is increasing rapidly

in other countries also, stimulated by the rapidly expanding technologies in these countries in recent years. There is also a movement to harmonize standards among certain countries, particularly in Europe. The policy in many countries is to base the national standards on lEC and ISO Recommendations whenever possible to do so. For example, India, which formerly based its standards on British,

French, German, or U.S. standards, is now basing them on lEC and ISO

Recommendations. Other developing countries are also looking to I EC and

ISO for their standards. The countries of Europe harmonizing their stan- dards are also using international recommendations insofar as possible.

Thus, if engineering practices in the United States are to be used internationally, they must be incorporated into the I EC and ISO Recommendations.

9.3 THE CRITICAL DECADE AHEAD

There were slightly over 400 I EC Recommendations and about 1,200

ISO Recommendations issued at the end of 1969. This number must be in- creased by a factor of 10 or more to meet minimum requirements of a

technological world economy. Currently, there is great pressure on lEC and

ISO to speed the issuance of recommendations. These organizations are responding as evidenced by the data in figures 1 and 2 which show the standards issued yearly by lEC and ISO, respectively since 1950. Tables 3 and

4 summarize the same data in 5-year periods. Nearly two-thirds of the inter- national recommendations have been issued in the past 5 years and the pace

of issuance is accelerating. The worldwide impetus for standards development should result in drafting most of the international recommendations

422-764 OL - 71 - 3
28 ENGINEERING STANDARDS

1950 54 57 60 63 66 69

YEAR

1951 54 57 60 63 66 69

YEAR

during the next 10 years. In this critical decade of standards development

the United States cannot afford to be absent from the negotiations if it ex- pects to have its technology and practices reflected in emerging international

standards.
MAGNITUDE OF STANDARDIZATION 29

TABLE 3. lEC Recommendations

Percent 1906-1938 60 issued, 14 have been revised since 1950, 3 are still 1 active, remainder superseded or discontinued. 1938-1949 None issued. 1950-1954 13 issued, 4 revised 3 1955-1959 53 issued, 16 revised 13 1960-1964 94 issued, 32 revised 24 1965-1969 272 issued, 42 revised 59

Total 1950-1969 432 issued, 94 revised 100 TABLE 4. ISO Recommendations

Percent 1950-1954 11 issued 1 1955-1959 125 issued 10 1960-1964 283 issued, 1 revised 23 1965-1969 786 issued, 36 revised 66

Total 1950-1969 1206 issued, 37 revised 100

Cost of sending delegates overseas to meetings is privately financed,

generally by individual companies or organizations paying the cost of travel and salary of their employees who are delegates. Thus far, U.S. participation

and success in having U.S. standards adopted internationally are due mainly

to the interest and financial support of a few organizations. The necessary

continuity of representation by competent individuals is also dependent on

the interest of their employers. This cost to individual companies is perhaps

the principal deterrent to participation in many international committees.

Travel expenses of a delegate to an overseas meeting averages about $800.

Thus, to send two delegates to each of the estimated 1 , 1 00 meetings of committees, subcommittees, and working groups of lEC and ISO each year

would cost nearly $2,000,000. This cost does not include salaries of

delegates for time spent at meetings or devoted to committee activities between meetings. The costs are much higher when the Secretariat of a committee is held. As a result, the U.S. has 65 Secretariats of I EC and ISO

Committees and Subcommittees as compared to France and England which

have about 1 30 each and Germany which has over 70. Standards activities in the United States, by virtue of their voluntary nature, have been free from any form of government control, a freedom

cherished by ANSI and the industries. As a consequence, participation in in- ternational standardization varies from one industry to another. Even those

industries most interested in international standardization generally support

only direct technical involvement and they are reluctant to support overhead

type of coordinating activity, particularly those required by having a

Secretariat of a Committee with its many advantages.

It begins to appear that the freely voluntary process which worked

domestically in spite of its shortcomings will not meet the challenge of the fu- ture on two fronts. Domestically consumers are being heard and will demand

a voice in establishing standards. Internationally, effectiveness in lEC and
30 ENGINEERING STANDARDS

ISO requires that the U.S. point of view be presented at all meetings, and not

just those of interest to particular producers. Whatever readjustments must

be made, it is quite clear that the critical decade has already begun and that international standardization will move forward toward completion of the

bulk of the work in this decade. If the U.S. turns its back or disassociates, in- ternational standardization will still continue and serve the needs of others.

The U.S. can let it do so and try to adjust later. Alternatively, the U.S. can become a full participant and help formulate standards consistent with its practices.

The increasing rate of standards development is already creating problems

in processing the large number of documents. There is an iirf^ent need for

review at both the national and international levels of the administrative

process involved in the issuance of standards in order to handle the increasing numbers.
10. MEASURING UNITS IN

ENGINEERING STANDARDS

Engineering standards can be based on any system of measuring units and

can be converted from one system to another. However, the use of a com- mon system would eliminate both errors that may be introduced by conversion of units and the man-hours that are required for such conversion.

As previously noted, the role of measurement units depends on the

category of the standard; that is. dimensional specification, quality specification, method of test, or descriptive standard. A survey of the ISO Recommendations in the 1970 catalog indicates that about 25 percent are dimensional specifications, about 15 percent are quality standards, about 45 per- cent are methods of test, and about 15 percent are descriptive standards. An

exact breakdown is not possible since a single recommendation could be

placed in more than one category. A similar breakdown for the standards is- sued in the United States is not possible, since there is no composite list and

there is considerable duplication. However, the distribution would probably

be about the same as that for the 1,200 ISO Recommendations since they

are a typical representation of national standards. If company standards were surveyed, the proportion of dimensional specifications would probably

be higher than 25 percent since the dimensions of most products are not standardized nationally.

Since descriptive standards do not have measurement units and since

units in methods of test and quality specifications serve only as a language,

measurement units do not have an important role in about 75 percent of en- gineering standards. Even among the 25 percent that are dimensional specifications, measurement units are not at issue where sizes are already agreed

internationally. For the other dimensional specifications which are now in31
32 ENGINEERING STANDARDS

compatible, there is an opportunity during standardization to adopt more ra- tional sizes for international use. Some of the existing I EC and ISO Recommendations include two systems

of units and two series of sizes based on the inch and meter, respectively.

However, the present tendency is to use SI units as evidenced by the following excerpt from Resolution 37 adopted by ISO Council in September 1969:

"The Council . . . instructs the Secretary-General to ensure that from 1 January 1970 the units contained in ISO/RIOOO are used in all Draft ISO

Recommendations submitted to Member Bodies, together with corresponding values in other units if deemed desirable, and to make every effort to en- courage Technical Committees to accept SI units as the first preference . .

. (ISO Recommendation RIOOO is entitled "Rules for the use of units of

the International System of Units and a selection of the decimal multiples

and submultiples of the SI units" and is reproduced in appendix II by per- mission of the Americal National Standards Institute.) Thus, future national

standards which do not use Si are not likely to receive due consideration

in the development of international standards, and the nations concerned

will be at a disadvantage in future dealings with nations using SI. This trend was recognized by ASTM when it issued the ASTM Metric Practice

Guide in 1964. The 1970 revision of this Guide is reproduced in appendix

III by permission of the American Society for Testing and Materials. In order to promote ASTM Standards internationally, SI units are now

required in addition to the customary units. ASME, SAE, and other standardization organizations have taken similar action, either requiring or rec- ommending inclusion of SI units in their standards.

The importance of measurement units in international negotiations is well

summarized in the following statement of a member of the Society of

Plastics Industry given in the report presented at the first National Metric

Study Conference in Deerfield, Massachusetts: "I have been involved for sometime with the industry's representation to ISO, particularly with TC

5/SC6 (Ed. Plastic Pipe and Fittings). The United States is in a weakened

position when we constantly have to fight for inclusion of conversion tables

in recommendations and other documents being written by ISO from time to time. Things which are very important to the United States in the Stan- dardization effort must be defended vigorously by delegates from the United

States. If we spend much of our time in persuasion, trying to incorporate

conversion tables, and defend our indefensible position on the use of the

pounds and inches, we make ourselves ineffectual on the things that really are important to the United States in the world market."

In addition to uniformity in language, the use of SI units in engineering

standards simplifies the measurement system and calculations. Numerous

units for the same property in customary systems, either U.S. or metric,

make conversions within a system necessary. The factors for converting

must be either memorized or obtained from published tables. For example,

in metric countries, the following units for energy are used in different fields of science and technology: calorie (6 variations), electron volt, erg, frigorie,

(metric) horsepower-hour, joule, kilogram (force)-meter, kilowatt-hour, liter- atmosphere, thermic, and (metric) ton of TNT. In the U.S., the following
MEASURING UNITS IN ENGINEERING STANDARDS 33

units for energy are used: BTU (5 variations), calorie (6 variations), cubic

foot-atmosphere, electron volt, foot-pound (force), foot-poundal. horsepower-hour (4 variations), inch-pound (force), kilowatt-hour, therm, and

ton of TNT. Few, if any, engineers or scientists can make these conversions

without the use of handbooks or other publications that give the conversion

factors. In linear measure, there are over 50 units used in the U.S., including

20 customary metric units. Linear measure is further complicated by the nu- merous gages for metal sheet, strip, and wire. Over 70 gage systems were

developed in various countries and used in the early part of this century.

Although many are no longer used, there are still about 30 gage systems, 10

of which are being used in the United States. In the International System of Units (SI), there is one and only one unit

for a particular property. The same name is not used for the units of two or more properties. Units derived from the six base and two supplementary

units are always related by a factor of unity. Thus, the confusion and complications in both U.S. and metric customary systems are eliminated in SI. To

facilitate the expression of different magnitudes of a property, 14 prefixes

may be used for multiples or submultiples of the units, ranging from a factor

of 10-1* (atto) to 10^2 (tera). For example, for the SI energy unit-joule, an at- tojoule is used in place of an electron volt (about 1/6 attojoule). a megajoule

is used in place of kilowatt-hour (3.6 megajoules), and a terajoule is used in place of a ton of TNT (about 4.2 terajoules). This simplification and ra- tionalization of the measurement system is the principal reason for the inclusion of SI units in new and revised international and national standards, and

for their mandatory or proposed mandatory use in some 25 countries.

The inclusion of SI units in engineering standards is a recent innovation.

Except for standards in which the metric customary and SI units are identi- cal (primarily some length, mass and electrical units), the first standards in- corporating SI units for all properties were published in 1967. Interestingly,

they included several British Standards and one ASTM Standard. Although

the survey of standards issued during the last few years in metric countries

is sketchy, it appears that the incorporation of SI units in their national standards began even later. Thus, the measurement units in engineering standards are undergoing change in both metric and nonmetric countries, and it appears that standards of most, if not all, countries will have SI units in the

future.
11. DIMENSIONAL SPECIFICATIONS

n.l GEOMETRY

Spatial geometry is the important feature of engineering standards in which critical dimensions are involved. This geometry is not governed by the

measuring units, but may be related to them. For example, electrical receptacles and plugs must have the same spatial geometry in order to fit and be in- terchangeable. The dimensions can be measured or expressed in either U.S.

customary or metric units. Further, the dimensions may or may not be simple whole numbers (or multiples of binary fractions) in either system of units. However, there is a tendency in existing standards to use whole numbers,

multiples of binary fractions, or simple decimals in the system of units used

so that products based on different systems are not interchangeable. On the

other hand, products based on the same units ofmeasurement may not be in- terchangeable; e.g., products made in different metric countries are frequently not interchangeable since the spatial geometry differs. Likewise,

British and U.S. pipe threads are not interchangeable even though both are based on the inch unit.

n.2 STANDARDIZATION OF DIMENSIONS

The dimensions of most products are governed by company standards.

National and international standards exist for the dimensions of relatively

few products. However, these standard products are mainly basic commodities in common supply for use in many industries; for example, sheet and

structural metal, wire and rod, screw fasteners, pipe, and bearings. Hence,

the dimensional standards for these products influence company standards

34
DIMENSIONAL SPECIFICATIONS 35

for final products. For example, drill sizes influence hole sizes, fastener

dimensions influence flange dimensions, etc. The dimensional standards for such common items comprise about 25 per- cent of national and international standards, but they are the most difficult to standardize internationally. The design and sizing of products are generally

related to the customary units of measurements and the engineering practices in the various countries. International standardization for spatial in- terchangeability can be achieved only by agreeing to a single system of units

and practices for the design, but actual dimensions may be expressed in customary units.

11.3 STANDARD SIZES FOR PRODUCTS

Currently, standards for most products made in a series of sizes base the

sizes on whole numbers, multiples of binary fractions, or simple decimals in the system of units used. The sizes form an arithmetic progression, or

several arithmetic progressions with larger steps for larger sizes. In the U.S.,

the steps are generally multiples of the binary fractions; namely, 1/64, 1/32,

1/16, 1/8, 1/4, and 1/2 inch. In metric countries, the steps tend to be multiples of 0. 1 , 0.5, 1,2,5, and 10 mm. Thus, U.S. and metric sizes for a particular product differ. The metric sizes in different countries may also differ since the same progression is not always used. For a few products, the same

sizes are used internationally; for example, most sizes of ball bearings used

in the U.S. are metric and threaded fasteners for aircraft used in metric countries are generally U.S. sizes. ISO is encouraging the international standardization of sizes based on the

rational system of preferred numbers wherever possible. These numbers

progress geometrically by the fifth, tenth, twentieth or fortieth root of 10 depending on the size of the steps desired. Table 5 is taken from ISO Recommendation R3 and gives the preferred numbers for the four series R5, RIO,

R20 and R40. These numbers are rounded slightly from the theoretical

values in column 7, but deviate from them by less than 1 .3 percent.

The series can be extended to higher or lower values by multiplying or

dividing by 10, 100, 1000, etc. ISO Recommendation R497 gives the following advantages for adhering

strictly to preferred numbers:

"2.1 Best progression

Preferred numbers ensure the best progression from the point of view of

regularity and the possibility of adapting them to new requirements for the creation of closer series by the insertion of inter- mediate values.

"2.2 Universal applicability

Preferred numbers offer the most logical means of uninterrupted coverage of

the complete range of requirements in a given field (power of

motors, output of pumps, etc.).
36 ENGINEERING STANDARDS

TABLE 5. ISO Recommendation R3, July 1953.

(Preferred Numbers — Series of Preferred Numbers)

(1. Basic Series of Preferred Numbers]

Basic series

number

Theoretical values Percentage

differences between

basic series and R5 RIO R20 R40 calculated values Mantissae

of lOganinma

Calculated

values

(1) (2) (3) (4) (5) (6) (7) (8)

1.00 1.00 1.00 1.00 0 000 1.0000 0

1.06 1 025 1.0593 + 0.07

1.12 1.12 2 050 1.1220 -0.18

1.18 3 075 1.1885 -0.71

1.25 1.25 1.25 4 100 1.2589 -0.71

1.32 5 125 1.3335 -1.01

1.40 1.40 6 150 1.4125 -0.88

1.50 7 175 1.4962 + 0.25

1.60 1.60 1.60 1.60 8 200 1.5849 + 0.95

1.70 9 225 1.6788 + 1.26

1.80 1.80 10 250 1.7783 + 1.22

1.90 1275 1.8836 + 0.87

2.00 2.00 2.00 12 300 1.9953 + 0.24

2.12 13 325 2.1135 + 0.31 2.24 2.24 14 350 2.2387 + 0.06

2.36 15 375 2.3714 -0.48

2.50 2.50 2.50 2.50 16 400 2.5119 -0.47

2.65 17 425 2.6607 -0.40

2.80 2.80 18 450 2.8184 -0.65

3.00 19 475 2.9854 + 0.49

3.15 3.15 3.15 20 500 3.1623 -0.39

3.35 21 525 3.3497 + 0.01 3.55 3.55 22 550 3.5481 + 0.05

3.75 23 575 3.7584 -0.22

4.00 4.00 4.00 4.00 24 600 3.9811 + 0.47

4.25 25 625 4.2170 + 0.78 4.50 4.50 26 650 4.4668 + 0.74

4.75 27 675 4.7315 + 0.39

5.00 5.00 5.00 28 700 5.0119 -0.24

5.30 29 725 5.3088 -0.17

5.60 5.60 30 750 5.6234 -0.42

6.00 31 775 5.9566 + 0.73 6.30 6.30 6.30 6.30 32 800 6.3096 -0.15

6.70 33 825 6.6834 + 0.25

7.10 7.10 34 850 7.0795 + 0.29

7.50 35 875 7.4989 + 0.01 8.00 8.00 8.00 36 900 7.9433 + 0.71 8.50 37 925 8.4140 + 1.02 9.00 9.00 38 950 8.9125 + 0.98 9.50 39 975 9.4406 + 0.63 10.00 10.00 10.00 10.00 40 000 10.0000 0
DIMENSIONAL SPECIFICATIONS 37

"2.3 Simplification of technical and commercial calculations

Since the products and quotients of preferred numbers are by definition also

preferred numbers, calculations, which should be made by using

the logarithmic values or serial numbers and not the preferred

numbers themselves, are considerably simplified, especially

when the series of values (dimensions, list prices, etc.) are multiplied or divided in the same proportions.

"2.4 Conversion into other systems of measurement

Conversion into other systems of measurement is greatly facilitated when

the series of values in which the measurements are expressed

comprise preferred numbers and, at the same time, the conversion factors approximate to preferred numbers."

Preferred numbers can be used with any measurement unit. However,

when standard sizes are based on preferred numbers in ISO Recommendations, the meter or one of its submultiples is always used.

11.4 APPLICATION OF PREFERRED NUMBERS

11.4.1 SHEET METAL AND WIRE

ISO Recommendation R388 gives the preferred thicknesses of sheet

metal and diameters of wire. Table 6 gives a comparison of the R20 series in ISO/R388 (last 2 cols.) with customary U.S. gages for steel sheet (col. 2), steel wire (col. 3), and nonferrous sheet and wire (American wire gage) (col.

4). The AWG and ISO values (cols. 4 and 5) correspond quite closely, particularly for the higher gage numbers, since the American wire gage is also

based on a geometric progression with a ratio between adjacent gages of

1.123 as compared to 1.122 for the R20 series of preferred numbers. The

steel gages do not follow a regular geometric progression and do not agree

with each other. In addition to the three gages given in table 2, seven other

gages are used for sheet metal and wire in the U.S. About 30 gage systems

are used in various countries. The confusion caused by these numerous

gages used either within or outside the U.S. would be avoided by the universal use of the preferred sizes in ISO/R388. Further, since the odd number

gage sizes are seldom used for many products, the stocking of only the RIO

sizes could achieve considerable economy and would suffice for nearly all needs. It should be noted that ANSI B32.1 Preferred Thicknesses for Uncoated Thin Flat Metals and ANSI B32.2 Preferred Diameters of Round

Wire use preferred numbers. The sizes in ANSI B32.2 up to 5 mm conform

to those in ISO/R388 and a large number of the sizes in ANSI 832. 1 are also in accord. The extent to which these standards are replacing the gage

sizes in table 6 has not been determined.
ENGINEERING STANDARDS

TABLE 6. Sheet Metal Thickness and Wire Diameter

Gage Steel Steel AWG ISO Rec. No. R388*

sheet wire wire

inch inch inch inch mm

7/0 .4900 .6299 16.000

6/0 .4615 .5800 .5518 14.000

5/0 .4305 .5165 .4921 12.500

4/0 .3938 .4600 .4409 1 1.200

3/0 .3625 .4096 .3937 10.000

2/0 .3310 .3648 .3543 9.000 0 .3065 .3249 .3150 8.000

1 .2830 .2893 .2795 7.100

2 .2625 .2576 .2480 6.300

3 .2391 .2437 .2294 .2205 5.600 4 .2242 .2253 .2043 .1969 5.000

5 .2092 .2070 .1819 .1772 4.500

6 .1943 .1920 .1620 .1575 4.000

7 .1793 .1770 .1443 .1398 3.550

8 .1644 .1620 .1285 .1240 3.150

9 .1495 .1483 .1144 .1 102 2.800

10 . 1 345 .1350 .1019 .0984 2.500

1.1 196 .1205 .0907 .0882 2.240

12 .1046 .1055 .0808 .0787 2.000

13 .0897 .0915 .0720 .0709 1.800

14 .0747 .0800 .0641 .0630 1.600

15 .0673 .0720 .0571 .0552 1.400

16 .0598 .0625 .0508 .0492 1.250

17 .0538 .0540 .0453 .0441 1.120

18 .0478 .0475 .0403 .0394 1.000

19 .0418 .0410 .0359 .0354 .900 20 .0359 .0348 .0320 .0315 .800

21 .0329 .0317 .0285 .0280 .710 22 .0299 .0286 .0253 .0248 .630

23 .0269 .0258 .0226 .0221 .560 24 .0239 .0230 .0201 .0197 .500

25 .0209 .0204 .0179 .0177 .450 26 .0179 .0181 .0159 .0158 .400 27 .0164 .0173 .0142 .0140 .355 28 .0149 .0162 .0126 .0124 .315 29 .0135 .0150 .01 13 .01 10 .280 30 .0120 .0140 .0100 .0098 .250

31 .0105 .0132 .0089 .0088 .224 32 .0097 .0128 .0080 .0079 .200

33 .0090 .0118 .0071 .0071 .180 34 .0082 .0104 .0063 .0063 .160

35 .0075 .0095 .0056 .0055 .140 36 .0067 .0090 .0050 .0049 .125 37 .0064 .0085 .0045 .0044 .112 38 .0060 .0080 .0040 .0039 .100 39 .0075 .0035 .0035 .090 40 .0070 .0031 .0032 .080

* mm values are R2U preferred numbers, the inch values are equivalents.
DIMENSIONAL SPECIFICATIONS 39

11.4.2 RUBBER HOSE

Another illustration of the use of preferred numbers is for bore sizes of

rubber hose. International agreement between metric and nonmetric countries was achieved by the use of the RIO series of preferred numbers. A comparison of the ISO and conventional bore sizes used in both metric and nonmetric countries is given in table 7. The list omits several conventional bore

sizes found unnecessary when sizes were based on a rational basis. The ISO

sizes are taken from ISO Recommendation R 1 307 and are based on the R 1

0

series. They correspond reasonably well with conventional inch and metric

sizes and with few exceptions are within the tolerances permitted in the conventional sizes. Thus, the application of preferred numbers achieves econo- my both through reduction in number of sizes and through international

standardization.

TABLE 7. Bore Sizes for Rubber Hose

ISO* Conventional

mm inch inch** mm***

3.2 0.126 y% 3.5 4 .157 %2

5 .197 3/l6 5 6.3 .248 V4 6(6) 8 .315 5/l6 8 10 .394 3/8 10(9) 12.5 .492 V2 12(13) 16 .630 5/8 15(16) 20 .787 3/4 20(19) 25 .984 1 25(25)

31.5 1.24 IV4 30(32) 40 1.57 IV2 40(38) 50 1.97 2 50(50) 63 2.48 2V2 60(63) 80 3.15 3 75(75) 100 3.94 4 100(100)

125 4.92 5 125 160 6.30 6 150 200 7.87 8 200 250 9.84 10 250

315 12.40 12 300

*The millimeter values correspond to RIO series of preferred numbers.

**Counlries using English units. ***Countries using metric units; values in parentheses were used in some metric countries.
40 ENGINEERING STANDARDS

11.4.3 ROUNDING OF PREFERRED NUMBERS

Sometimes it is not possible to use the preferred numbers in table 5; e.g., a gear must have a whole number of teeth. ISO Recommendation R497

gives rules for further rounding the preferred numbers in table 5 when necessary. Greater rounding is also suggested when the number of significant

figures in the preferred number would be misleading; e.g., 2.24 would be

rounded to 2.2 if the uncertainty were 10 percent. However, ISO/R497

urges that the preferred numbers in table 5 be used wherever possible to

facilitate national and international standardization, to simplify the problem

of sizing, and to facilitate engineering calculations. For example, if preferred

numbers are used for linear dimensions, then areas and volumes are preferred numbers with about 2 and 3 times the deviations given in column

8 of table 5.

11.5 STANDARDIZATION OF NONPREFERRED SIZES

Although the choice of measuring unit is independent of the choice of

sizes (preferred numbers or otherwise), the two are joined in engineering

standards. Maximum economy and simplification is achieved when the same

measuring units and sizes are used internationally. Although ISO en- courages the use of preferred numbers for established standard sizes, there

are many ISO Recommendations in which standard sizes are not based on

preferred numbers. The following examples are illustrative:

11.5.1 ROLLING BEARINGS

Bore sizes in ISO Recommendation R15 conform to the R40 series of

preferred numbers above 500 mm. Between 3 and 500 mm, the sizes are a whole number of millimeters, many of which are not preferred numbers. The

steps between sizes are 1, 2, 3, or 5 mm for bores between 3 and 50 mm.

From 50 to 110 mm, steps of 5 mm are used. From 110 to 200 mm, the steps

are 10 mm and from 200 to 500 mm, the steps are 20 mm. These ISO sizes

reflect past practice. The present tendency in this country is to use metric

bore sizes. However, some metric bearings produced in the U.S. do not con- form with ISO Recommendations for dimensions other than bore size.

11.5.2 STEEL PIPE

Table 8 gives the nominal size, outside diameter, and inside diameter of

steel pipe as specified in ANS 36.10-1959 and ASTM A53-68 for standard

pipe and in ISO Recommendation R65 (medium series). Although neither

the dimensions for outside nor inside diameter are based on preferred numbers, the inside diameters approximate the RIO series of preferred numbers

given in the last column of table 8. The RIO series includes both 8 and 10
DIMENSIONAL SPECIFICATIONS 41

TABLE 8. Dimensions of Standard Steel Pipe

Nominal size Outside diameter Inside diameter

USA ' ISO-' USA ' ISO - USA ' ISO - RIO '

inch mm inch mm mm iu ch mm mm

Vs 6 0.405 10.2 10.2 0.269 6.8 6.2 6.5 V4 8 .540 13.7 13.6 .364 9.2 8.9 8.0 10.0

3/8 10 .675 17.1 17.1 .493 12.5 12.4 12.5 V2 15 .840 21.3 21.4 .622 15.8 16.1 16.0

3/4 20 1.050 26.7 26.9 .824 20.9 21.6 20.0

1 25 1.315 33.4 33.8 1.049 26.6 27.3 25.0

IV4 32 1 .ooU 42.4 1 "5 OA 1 . JoO 35.9 31.5

IV2 40 1.900 48.3 48.4 1.610 40.9 41.9 40.0

2 50 2.375 60.3 60.2 2.067 52.5 52.9 50.0 2V2 65 2.875 73.0 76.0 2.469 62.7 68.7 63.0

3 80 3.500 88.9 88.8 3.068 77.9 80.7 80.0 3V2 90 4.000 101.6 101.2 3.548 90.1 93.1 4 100 4.500 1 14.3 1 14.0 4.026 102.3 105.0 100.0

5 125 5.563 141.3 139.6 5.047 128.2 129.9 125.0 6 150 6.625 168.3 165.2 6.065 154.1 155.5 160.0

8 200 8.625 219.1 (^) 7.981 202.7 200.0

10 250 10.750 273.0 C) 9.970 253.2 250.0

12 300 12.750 323.9 V) 12.000 304.8 315.0

' ASTM A53-68, standard pipe.

- ISO Recommendation R65, Medium series.

' RIO Series of preferred number (See table 5).

^ USA dimensions are used. mm but no 9 mm size. Otherwise, the RIO series identifies the pipe sizes at

least as well as the nominal sizes, either inch or mm. Except for two sizes,

the outside diameters are essentially the same for corresponding U.S. and

ISO sizes. The outside diameter of the 65 mm pipe is slightly larger than that of the 2 1/2-inch pipe, and the reverse applies for the 150 mm and 6-inch

pipes. The wall thickness and hence strength of neither U.S. pipe nor ISO

pipe increase with size in a uniform manner. There is an abrupt increase in thickness of U.S. pipe between 2 and 2 1/2 inch so that wall thickness of

U.S. pipe above 2-inch nominal size is between 25 and 30 percent greater

than ISO pipe. Pipe standards are discussed in more detail later.

11.5.3 TEST SIEVES

Aperture sizes of test sieves in ISO Recommendation R565 progress by

the square root 2, instead of one of the preferred series in table 5. U.S. standard sieves in the numbered series progress by the fourth root of 2, so that every other sieve is an ISO size. There is also an inch series of U.S. sieves

ranging from 1/4 to 4 inch in steps of 1/16, 1/8, 1/4, or 1/2 inch, depending on the size. Some of the inch sieves have apertures corresponding to the ISO

sieves. The ISO sieves should suffice for most, if not all, sieve testing.
42 ENGINEERING STANDARDS

11.6 BUILDING DIMENSIONS

In construction, the present tendency is to select dimensions that are multiples of some basic module. For example, windows and doors are made in sizes that are multiples of 2 inches. ISO Recommendation R1006 specifies

100 mm for the basic module, but in an Annex permits 4 inches (101 .6 mm)

for countries using the "foot-inch system of measurement." This difference

of 1.6 percent in the dimensions can restrict trade between countries using

different basic modules, particularly for components such as appliances,

cabinets, doors, panels, and windows.

11.7 TOLERANCES

Although dimensional specifications can be expressed in any system of

units, the system on which the dimensions are based does have an influence.

Both the specified value for a dimension and the tolerances are generally

selected to be convenient numbers in the selected system. For example, the

selection of a dimension and tolerance might be 0.375 ±0.015 inch in the

U.S. customary system or 10.00 ±0.40 mm in the metric system. When the

values in one system are converted to the other, they become 9.525 ± 0.38

mm and 0.3937 ±0.01575 inch, respectively. Since these numbers reflect a precision greater than required, they are rounded to reflect the precision of

the original numbers. This rounding causes problems. If the original limits are not violated, the converted limits are always within the original limits; for

example, 9.52 ±0.37 mm and 0.394 ±0.0 15 inch. Thus, a U.S. manufacturer using a dimensional specification based on metric units and converted

to the inch unit is at a disadvantage. Conversely, a manufacturer in a metric

country is at a disadvantage when using an inch-based specification converted to metric units. The conversion of tolerances in dimensional specifications expressed in both metric and inch units is a problem that is now confronting organizations which are including SI units in their standards.
12 QUALITY SPECIFICATIONS

These standards are becoming more numerous and important. About 15 percent of ISO Recommendations relate to product quality; most of them

have been issued in the last few years. They may include requirements for chemical composition, physical properties, and performance or simulated

service. Safety standards are included among them. Measurement units in quality-specifications serve only as a language. For example, the minimum

requirement for tensile strength can be expressed in pound-force per square

inch, kilogram-force per square millimeter, or newton per square meter. Whether requirements are expressed in the same or different measure- ment units, standards of different countries may not be compatible. For ex- ample, ISO Recommendation R898 gives the requirements for mechanical

properties of bolts. For comparable inch and metric bolts, the hardness

limits for metric bolts tend to be lower than those for inch bolts reflecting dif- ferences in practice between U.S. and metric countries. Thus, for one grade

of bolts, the limits for Brinell hardness are 1 10 to 170 for metric bolts and

121 to 241 for inch bolts. For another grade, the limits are 280 to 365 for metric bolts and 302 to 352 for inch bolts. In one case, the metric bolts have

lower and narrower limits than the inch bolts. In the other case, the metric

bolts have wider limits and extend above and below those for inch bolts. Since there is considerable overlap in the hardness requirements for the vari- ous grades, a manufacturer could make metric and inch bolts within the same

hardness limits by sacrificing some of the tolerances permitted by the

specifications.

Quality specifications may also differ because different characteristics are

specified in national standards. For example, the seat belt standard in the

U.S. has requirements for resistance to microbiological deterioration and to

light deterioration; whereas, the British Standard does not. On the other

43

422-764 OL - 71 - 4
44 QUALITY SPECIFICATIONS

hand, the British Standard has a simulated service requirement which the

U.S. standard does not have.

To recapitulate, incompatibility of quality specifications may arise from

differences in the limits for a particular requirement or from differences in the choice of requirements included in the specification. Measurement units

per se are not the cause ofincompatibility in these standards.

J
13. METHODS OF TEST

Standard methods of test comprise the largest portion of engineering stan- dards; about 45 percent of the ISO Recommendations issued thus far are in this category. Measurement units in these standards, as in quality specifications, serve as a language. However, needless incompatibility can arise

when a standard requires a test to be conducted on equipment graduated in a particular system of units, or the procedure is written for convenient use

with one system and inconvenient with another system. For example, many

U.S. standards prescribe a specimen having a cross sectional area of a simple

fraction of a square inch, and a tensile tester graduated in a multiple or submultiple of pound-force and having a rate of traverse expressed in inches per

minute. Such a test cannot be conducted in a laboratory operating with metric equipment. Methods so written are not acceptable to metric countries.

The same basic procedure can be written for use in laboratories operating

with either measurement units. Results obtained in U.S. customary units can

easily be translated into SI units and vice versa. U.S. standards so written

are considered on their merits in the international forum with those of other

nations.

ASTM recognized the need for metric units in their standards to have

them accepted internationally and issued its first metric practice guide in 1964. This guide which used customary metric units was revised in 1966

using SI units, and again revised in 1970 (see app. III). However, the application of the guide has not been consistent. Some committees have included

only the exact SI equivalents of U.S. customary units; whereas, other committees have modified their standards to permit their use in laboratories

operating with either U.S. customary or SI units. International acceptance

of ASTM methods has been much greater in the latter case.

45
46 METHODS OF TEST

Other organizations promulgating standards have published very few containing metric units, except biological or chemical methods which use custo- mary metric units almost exclusively. However, ASME. SAE, and other or- ganizations have started to include SI units. The inclusion of SI units applies

to dimensional and quality specifications as well as methods of test. The

tempo has been increasing so that within 5 years SI units are likely to be in- cluded in most engineering standards.
14. DESCRIPTIVE STANDARDS

These standards which do not have measurement units comprise a substantial portion of engineering standards; about 15 percent of the ISO

Recommendations are in this category. Although measurement units are not

involved, the extent of incompatibility among national standards is comparable to that for other standards. In the case of terminology, the incompatibility arises from different meanings attached to the same word. Such dif- ferences exist even within a country among different industries. Many practices in descriptive standards are as difficult to resolve internationally as dif- ferences in dimensional specifications. For example, driving on the right side versus the left side of the highway, conventions regarding projections in en- gineering drawings, differences in color coding, and even conventions for designating time. These incompatibilities in descriptive standards support

the previous finding that the engineering practices, rather than the measure- ment units, are responsible for the differences in national standards. The

units may be a contributing factor in the engineering practice. In some

dimensional specifications, a change in the measurement unit may be beneficial in changing the engineering practices and resolving differences, but a change in units without a change in the practices would not resolve present

incompatibilities among standards ofany type.

47
15. lEC AND ELECTRICAL ENGINEERING

STANDARDS

15.1 BACKGROUND

Electrical engineers were among the first to realize that international stan- dardization would become a necessity in the modern world. A number of

electrical congresses were held at the end of the 19th and the beginning of

the 20th centuries at which it was agreed that a permanent organization was

needed to facilitate the coordination and unification of national elec- trotechnical standards in a methodical and continuous manner. As a result of

a resolution passed by the Chamber of Government delegates to the 1904

International Electrical Congress held in St. Louis, Missouri, the International Electrotechnical Commission (lEC) was organized in 1906. Lord Kelvin was the first president. The Central Office was in London until 1947

when it was transferred to Geneva. lEC was the only organization con- cerned with voluntary international standardization that survived the two

World Wars. Although affiliated with ISO as its electrical division since

1947, lEC has retained its technical and administrative autonomy. The

membership in lEC has increased from 14 countries at its first meeting in 1908 to 41 countries today. The United States National Committee of the

lEC was founded in 1907, and has been affiliated with the American National Standards Institutes or its predecessors since 1931. I EC has become

the leading international organization for engineering standards in the electrical and electronics industries.

48
lEC AND ELECTRICAL ENGINEERING STANDARDS 49

15.2 MEASUREMENT UNITS

At the beginning of this century, nine systems of units had been in- troduced. Therefore, the early electrical congresses and later lEC were

greatly concerned with the standardization of measurement units as well as engineering practices. Three systems were extensively used for electrical units; namely, the CGS electrostatic units, the electromagnetic units, and the

practical units. Among these systems was the MKS system proposed by

Professor Giovanni Giorgi of the University of Rome in 1901 which subsequently became the basis for the International System of Units (SI)

adopted by the General Conference on Weights and Measures in 1960.

Professor David Robertson of Bristol University in a letter to the

Electrician in April 1904 independently advocated the adoption of a similar

MKS system by the St. Louis International Electrical Congress and sug- gested the "newton" for the unit of force and the "kram" for the unit of mass

in order to eliminate the prefix in the base unit "kilogram." The proposed

MKS system was little used until lEC decided to adopt it in 1935. After

further delay caused by World War II, the International Committee on

Weights and Measures recommended its adoption in 1946 and the ampere was adopted as a base unit at the Ninth General Conference on Weights and

Measures in 1948. The system was further developed and finally SI was for- mally adopted in 1960.

The leading role of lEC in developing and promoting the rationalized

MKS system accounts for the number of special names given to derived

electrical units being more numerous than the number of special names for

all other derived units. For example, of the following names that have been

given to the base and derived SI units, eight of the 15 special names are for

derived electrical units:

Base General Electricity Light meter hertz coulomb lumen

kilogram joule farad lux second newton henry ampere watt ohm

kelvin pascal** tesla candela volt radian* weber

steradian* Siemens**

Supplementary units. •Proposed names.

These eight electrical units together with the ampere, hertz and watt are now

used in the U.S. and other countries. U.S. customary units are frequently

used in place of the other base and general units in electrical and electronics

standards in the U.S. lEC Recommendations use the SI units and in some

instances also include such customary units as the inch.
50 ENGINEERING STANDARDS

15.3 lEC ORGANIZATION

Each of the 4 1 member countries of I EC is represented by a national committee. Although each member has nominally equal status and voice in developing lEC Recommendations, actual control resides in the technical

committees and subcommittees. The chairman and particularly the secretaries of committees have a great influence, and the possession of a secretariat

is a great asset to a nation in having its engineering practices incorporated

into an lEC Recommendation. Table 9 and figure 3 show the number of

chairmanships and secretariats of committees and subcommittees held by

member countries. They show the United Kingdom has the most chairmanships and secretariats, with France in second place. The U.S. holds the same number of chairmanships as France but is in fourth place in number of

secretariats, the Netherlands being in third place. Thus, the U.S. is among

the more active nations. However, this activity appears to be relatively recent since chairmanships and secretariats held by the U.S. are much

greater for the younger committees and subcommittees than for those

established many years ago. Currently, the U.S. participates in about 95 per- cent of the lEC technical committees and subcommittees, but participation

in working groups is estimated to be less than 50 percent.

TABLE 9. lEC Technical Committees and Subcommittees

(Distribution of Chairmen and Secretariats Among Countries)

Country Chairman Secretariat

Belgium 8 6 Canada 1 2 Czechoslovakia 0 1 Denmark 0 2 France 18 25 Germany 1

19 Hungary 6

India 1 1 Italy 14 8 Japan 2 1 Netherlands 12 23 Norway 2 0 Poland 1 1 Romania 1 0 Sweden 9 7 Switzerland 1

6 United Kingdom 33 27 USA 18 21 USSR 2 5
lEC AND ELECTRICAL ENGINEERING STANDARDS 51

FIGURE 3

DISTRIBUTION OF CHAIRMANSHIPS AND SECRETARIATS

lEC TECHNICAL COMMITTEES AND SUBCOMMITTEES

BELGIUM

CANADA

CZECHOSLOVAKIA

DENMARK

FRANCE

GERMANY

HUNGARY

INDIA ITALY

JAPAN

NETHERLANDS

NORWAY

POLAND

ROMANIA

SWEDEN

SWITZERLAND

UNITED KINGDOM

USA

USSR

En —n

\—

CHAIRMANSHIPS I SECRETARIATS C

10 20 30

NUMBER OF SECRETARIATS

15.4 lEC RECOMMENDATIONS

Many I EC Recommendations have several parts issued as separate documents, essentially each part being a separate recommendation. Counting

each such part, there were 436 lEC Recommendations in effect at the

beginning of 1 970. A list of these documents taken from the 1 970 Catalog of

the American National Standards Institute is given in table 10. These documents were reviewed and divided into those containing length

units and those having either no measurement unit or only electrical units

which are the same in all countries including the U.S. About one-third contained length units. They were examined in greater detail and will be

discussed later. Among the rest, only lEC Recommendation 38 on standard

voltages and I EC Recommendation 196 on standard frequencies were ex- amined. These two documents had two series of standard voltages and

frequencies reflecting differences in practices in different countries. For ex- ample, in North America the standard household electrical supply is single

phase 1 20 volts (two wire) or 1 20/240 volts (three wire), 60 hertz alternating current. In Europe, the standard supply is single phase 220 volts. 50 hertz al- ternating current. These supplies are not compatible and equipment

designed for one supply must be modified or adapted for use with the other

- supply. Although I EC was organized over 60 years ago, it was obviously not

early enough to prevent this incompatibility. Thus, there must be early stand-
52 ENGINEERING STANDARDS

ardization of new technological developments to prevent development of

diverse practices that can be harmonized only at great cost. It should again

be emphasized that measurement units were not involved in these diverse

practices.

The I EC Recommendations having length units were classified into the

following categories depending on the units in the original standard from

which the recommendation was developed:

A. All metric

B. Dominantly metric

C. Mixed

D. Dominantly inch

E. All inch

Since I EC Recommendations prescribe length dimensions in both metnc

and inch units, the following rationale was used to decide on the original

unit:

1. In a few instances, the original unit is identified in the recommendation.

2. For recommendations issued since the I EC rules for rounding and

significant digits were adopted, these rules were used to identify the

original unit.

3. For older recommendations, an original inch unit can occasionally be

identified when the value was derived from a conventional inch fraction. In other instances, a comparison of the terminal zeros in the

inch and metric values revealed the original unit.

Table 1 1 summarizes this examination of documents with length units. The

current editions of such I EC Recommendations are dated from 1955 to

1 969. They are grouped into documents having dates from 1 955 to 1 96 1 and

those from 1962 to 1969. Each category is subdivided into recommendations

on which a vote by the U.S. is recorded and those having no indication of

U.S. participation in voting. The following conclusions may be drawn from

the information in table 1 1

1. The number of documents involving length units that were issued

during the 7 years from 1955 to 1961 and still effective is less than

20 percent of the number issued during the 8 years from 1962 to 1969.

2. No document issued prior to 1962 is based on an original inch standard or predominantly inch standard.

3. The lack of inch-based documents issued prior to 1962 does not ap- pear to be due to the level of U.S. participation since the U.S. voted on 20 of the 23 recommendations (87%) issued during 1955 to 1961

and on 98 of the 134 recommendations (73%) issued during 1962 to 1969.

4. An appreciable portion (10%) of the recommendations issued during

the last 8 years are based on standards using all inch or predominantly inch length unit. However, there is no trend toward greater
lEC AND ELECTRICAL ENGINEERING STANDARDS 53

use of inch-based standards since more careful examination in- dicates eight of the 56 recommendations issued during 1962 to 1965 were inch-based and only six of the 78 recommendations issued during 1966 to 1969 were inch-based.

5. U.S. voted on 12 of the 14 recommendations (86%) based on inch or predominantly inch length unit and on 76 of the 106 recommendations (72%) based on metric or predominantly metric length unit is- sued during 1962 to 1969. Two inch-based recommendations were

adopted apparently without U.S. participation.

6. With respect to electrical engineering standards, the U.S. is bilingual

and apparently uses the metric length unit as frequently or more

frequently than the inch unit.

Table 12 lists the lEC recommendations by number which include a

length unit and corresponding national standards in the United States,

United Kingdom, Germany, Japan and India that were so indicated in the

catalogs of the standardizing organization and in France that were obtained

by correspondence with the Association Francaise de Normalization.

The length unit in the recommendation is indicated by letters A to E which

correspond to the five groups in table 1 1. ANSI catalog for 1970 indicates

that only two ANSI electrical standards are in agreement with I EC Recommendations (60 and 83) which have length units. The other ANSI

standards in table 1 2 are in partial agreement. The extent of agreement for the other national standards is difficult to determine in most instances, but some national standards catalogs do indicate the similarities and differences. In summary, it appears that measurement units are not a significant factor

in the incompatibility that exists between national electrical standards in the

U.S. and those in other countries. It also is evident that lEC has been able to reduce but has not been able to eliminate the diverse practices in electrical engineering. Early standardization of new technological developments is required to do so, and such standardization should be initiated at the inter- national, rather than the national, level. Failure to do so results in incompatibility of practices that increases costs unnecessarily. For example, the

diverse systems for color television in Europe and North America increases

the cost to interchange programs by satellite or otherwise.
54 ENGINEERING STANDARDS

TABLE 10

lEC RECOMMENDATIONS

The corresponding American National Standards are shown by cross references

enclosed in parentheses ( ). Since cross references must be brief, the

following system has been used: where there is complete agreement with an international recommendation, the words "Agrees with" precede the number

designation of the international recommendation; where there is partial

agreement, only the number designation is given. The actual relationships

can be determined only through careful comparison of the documents involved.

I EC No. 27 (1966) Letter Symbols to be Used m Electrical Technology 28 (1925) International Standards of Resistance for Copper

34-1 (1969) Rotating Electrical l\^achines, Part 1; Rating and Performance

34-1A (1965) Irregularities of Waveform. Supplement to Publi- cation 34-1 34-2 (1960) Recommendations on Determination of Efficiency of Rotating Electrical Ivlactiinery (Excluding Macfiines for Traction Vehicles) 34-3 (1968) Rotating Electrical tvlachines Part 3: Ratings and

Characteristics of Three-Phase. 50 Hz Turbine Type li^achines 34-4 (1967) Recommendations for Rotating Electrical IVIachinery (Excluding Machines for Traction Vehicles) Part 4: tiflethods for Determining Synchronous N/lachine Quantities from Tests 34-5 (1968) Rotating Electrical Machines Part 5: Degrees of Protection of Enclosures for Rotating Machinery

34-6 (1969) Rotating Electrical Machines: Part 6; Methods of Colling Rotating Machinery 38 (1967) Standard Voltages (C84. 1-1954 and C9,d.^-1967)

41 (1963) International Code for the Field Acceptance Tests of Hydraulic Turbines 43 (1960) Recommendations for AC Watt-Hour Meters

45 (1958) Recommendations for Steam Turbines, Part I; Specifi- cation 46 (1962) Recommendations for Steam Turbines, Part II, Rules

for Acceptance Tests,' Amendment 1 (1965) 48 (1961) Rules for Electric Traction Motors. 50-05 (1956) International Electrotechnical Vocabulary, Group

05: Fundamental Definitions 50-07 (1956) International Electrotechnical Vocabulary, Group

07: Electronics 50-08 (1960) International Electrotechnical Vocabulary, Group

08: Electro-Acoustics (SI. 1-1960} 50-10 (1956) International Electrotechnical Vocabulary, Group

1 0: Machines and Transformers

50-11 (1956) International Electrotechnical Vocabulary, Group

1 1 : Static Convertors 50-12 (1955) International Electrotechnical Vocabulary, Group

1 2: Transductors 50-15 (1957) International Electrotechnical Vocabulary, Group

15: Switchboards and Apparatus for Connection and Regulation (037.100-1966) 50-16 (1956) International Electrotechnical Vocabulary, Group

16: Protective Relays (C37. 100-1966)

lEC No

50-20 (1958) International Electrotechnical Vocabulary, Group

20 Scientific and Industrial Measuring Instruments 50-25 (1965) International Electrotechnical Vocabulary, Group

25: Generation, Transmission, and Distribution of Electrical Energy 50-26 (1968) International Electrotechnical Vocabulary, Nuclear Power Plants for Electric Energy Generation 50-30 (1957) International Electrotechnical Vocabulary, Group

30: Electric Traction 50-31 (1959) International Electrotechnical Vocabulary, Group

31: Signalling and Security Apparatus for Railways

50-35 (1958) International Electrotechnical Vocabulary, Group

35 Electromechanical Applications 50-37 (1966) International Electrotechnical Vocabulary, Group

37. Automatic Controlling and Regulating Systems

50-40 (1960) International Electrotechnical Vocabulary. Group

40: Electro-Heating Applications 50-45 (1958) International Electrotechnical Vocabulary. Group

45: Lighting 50-50 (1960) International Electrotechnical Vocabulary. Group

50: Electrochemistry and Electrometallurgy 50-62 (1961) International Electrotechnical Vocabulary. Groun

62 Waveguides

50-65 (1964) International Electrotechnical Vocabulary. Group

65: Radiology and Radiological Physics

50-66 (1968) International Electrotechnical Vocabulary: Detection and Measurement of Ionizing Radiation by Electric Means

50-70 (1959) International Electrotechnical Vocabulary. Group

70: Electro-Biology (C42. 80-1957)

51 (1960) Recommendations for Indicating Electrical Measuring Instruments and Their Accessories.

Amendment (1967),

52 (1960) Recommendations for Voltage Measurement by Means of Sphere-Gaps (one sphere earthed) (C68. 1-1968) 54 (1936) Recommendations for Standard Direction of Motion of Operating Devices and for Indicating Lamps for Circuit-Breakers 55-1 (1965) Tests on Impregnated Paper Insulated Metal- Sheathed Cables. Part 1: Cables for Alternating Voltages from

10 kV up to and including 66 kV (excluding Gas-Pressure, Oil- Filled and Non-Draining Cables) Amendment 1 (1967)
lEC AND ELECTRICAL ENGINEERING STANDARDS 55

I EC No. 55-2 (1965) Tests on Impregnated Paper Insulated Metal- Sheathed Cables, Part 2: Non-Draining Cables for Alternating Voltages from 10 kV uD to and inciudino 33 kV (excludina GasPressure Cables)

Amendment 1 (1967), 56-1 (1954) Specification for Alternating-Current Circuit-Breakers, Chapter I: Rules for Short-Circuit Conditions (second

edition, 1954), I Appropriate C37 Standards)

56-1-A (1959) Supplement to Chapter 1. Rules for Short-Circuit Conditions; a) Recommendations for the Unit Testing by Direct Methods of Circuit-Breakers for Making-Capacity and BreakingCapacity: b) Methods for Determining Inherent Resiriking- Voltage Waveforms

56-1 -B (1962) Amendments to Chapter

56-2 (1955) Specificiation for Alternating-Current Circuit-Breakers. Chapter II; Rules for Normal Load Conditions. Part 1. Rules

for Temperature Rise (Appropriate C37 Standards) 56-3 (1959) Specification for Alternating-Current Circuit-Breakers, Chapter II Rules for Normal Load Conditions, Part 2; Rules

for Operating Conditions, Part 3; Coordination of Rated Volt- ages, Rated Breaking-Capacities and Rated Normal Current

(Appropriate C37 Standards) 56-4 (1959) Specification for Alternating-Current Circuit-Breakers. Chapter III; Rules for Strength of Insulation; Chapter IV; Rules for the Selection of Circuit-Breakers for Service; Chapter

V; Rules for the Erection and Maintenance of Circuit-Breakers in Service. (Appropriate C37 Standards) Amendment 1 (1965), 56-5 (1963) Specification for Alternating-Current Circuit-Breakers, Guide to the Field Testing of Circuit-Breakers vnith Respect

to the Switching of Overhead Lines on No-Load (Appropriate C37 Standards) 56-6 (1963) Specification for Alternating-Current Circuit-Breakers, Guide to the Testing of Circuit-Breakers with Respect to the Switching of Cables on No-Load (Appropriate C37 Standards)

56-7 (1963) Specification for Alternating-Current Circuit-Breakers, Guide to the Testing of Circuit-Breakers, with Respect to the Switching of Shunt Capacitor Banks

59 (1938) Standard Current Ratings 60 (1962) High Voltage Test Techniques (Agrees with 068 7- 7968 and C77. 1-1943 (R1953j)

61-1 (1969) Lamp Caps and Holders Together with Gauges for the Control of Interchangeability and Safely, Part 1 Lamp Caps

(Appropriate C81 standards) S61-2 (1969) Lamp Caps and Holders Together with Gauges for the Control of Interchangeability and Safety, Part 2; Lampholders (Appropriate C81 standards) 61-3 (1969) Lamp Caps and Holders Together with Gauges for the Control of Interchangeability and Safety, Part 3; Gauges

(Appropriate C81 standards) 62 (1968) Marking Codes for Values and Tolerances of Resist- ors and Capacitors, Amendment 1 (1968), 63 (1963) Preferred Number Series for Resistors and Capacitors, [Agrees with C83 2-1949 (R1961)) Amendment 1 (1967) 64 (1961) Tungsten Filament Lamps for General Service.

64A (1962) Lamps with a Life of 2,500 Hours. Supplement to Publication 64, 65 (1965) Safety Requirements for Mains Operated Electronic and Related Equipment for Domestic and Similar General Use

(CEE 1-1965) Amendment 1 (1967). Appendix A (1969) Safety Requirements for Splash-Proof Mains

Operated Electronic Equipment.

66 (1953) Specification for Fuses for Voltages Not Exceeding

1,000 Volts for AC and DC

67 (1966) Dimensions of Electronic Tubes and Valves, including

lEC No 67A (1967) Supplement to Publication 67, sold separately. 68-1 (1968) Basic Environmental Testing Procedures for Electronic Components and Electronic Equipment, Part 1; General. 68-2 Basic Environmental Testing Procedures for Electronic Components and Electronic Equipment, Part 2: Tests (includes

all tests listed below)

68-2-1 (1966) Test A; Cold 68-2-2 (1966) Test B Dry Heat

68-2-3 (1969) Test Ca; Darno Heat Steady o'.ste 68-2-4 (1360) Test D; Acceleraied Damp l ieat 63-2-6 (1966) Test F; Vibration,

68-2-6A (1967) Supplement to Publication 6S-?-6,

68-2-6B (1967) Supplement to Publication 68-2-6,

68-2-6C (1969) Supplement to Publication 68-2-6

68-2-7 (1968) Test Ga; Acceleration, Steady State 63-2-8 (1980) Test H; Storage 68-2-10 (1968) Test J; Mould Growth,

68-2-10A (1969) SuoDlement to Publication 68-2-10 (19681,

68-2-11 (1964) Test Ka; Salt Mist 68-2-13 (1966) Test M; Low-Air Pressure 68-2-14 (1960) Test N. Change of Temperature

68-2-17 (1958) Test 0; Sealing 68-2-20 (1968) Test T; Soldering 68-2-21 (1960) Test U; Robustness of Terminations, inciudino

Amendment 1 (1967), to Pub. 68-2-21, 68-2-27 (1967) Test Ea: Shock. Supplement 68-2-27A (1968)

Note; All the above tests should be used in conjunction with Publication 68-1 68-2-28 (1968) Guidance for Damp Heat Tests 68-2-29 (1968) Test Eb; Bump

69 (1954) Recommended Methods of Measurement of Receiver;

for Amplitude Modulation Broadcast Transmissions (C16.19- 1951 (R1961)) 70 (1967) Power Capacitors. 70-A (1968) Supplement to Publication 70

71 (1967) Insulation Coordination,

(C92. 7-7967 and C84. 1-1954) 71-A (1962) Application Guide to Publication 71. 72-1 (1967) Dimensions and Output Ratings of Electrical Machines, Part 1; Foot-Mounted Electrical Machines with Shaft H ghts Between 56 and 315 mm (2-5/8 and 12-1/2 in.) (C50.8- 1n55) 72-2 (1967) Dimensions and Output Ratings of Electrical Machines. Part 2; Dimensions of Mounting Flanges 73 (1955) Recommendations Regarding the Color of PushButtons (C19. 1-1959) 74 (1963) Method for Assessing the Oxidation of Insulating Oils 76 (1967) Power Transformers (Appropriate C57. 12 Standards) 77 (1968) Rules tor Electric Traction Equipment

78 (1967) Characteristic Impedances and Dimensions of Radio- Frequency Coaxial Cables 79 (1957) Recommendations for the Construction of Flameproof Enclosures of Electrical Apparatus

79-2 (1962) Electrical Apparatus for Explosive Gas Atmospheres. Part 2; Pressurized Enclosures 79-3 (1963) Electrical Apparatus for Explosive Gas Atmosphere,

Part 3; Testing of Intrinsically Safe Apparatus

79-4 (1966) Electrical Apparatus for Explosive Gas Atmospheres. Part 4; Method of Test for Ignition Temperature

79-5 (1967) Electrical Apparatus for Explosive Gas Atmospheres, Part 5: Sand-Filled Apparatus,

79-5A (1969) Supplement to Publication 79-5 (1967).

-A-tt P R-l-CeS S U BJ E C T TO CHANGE WITHOUT NOTICE
56 ENGINEERING STANDARDS

I EC No. 79-6 (1966) Electrical Apparatus for Explosive Gas Atmospheres, Part 6: Oil-Immersed Apparatus

79-7 (1969) Electrical Apparatus for Explosive Gas Atmosptieres, Part 7: Construction and Test of Electrical Apparatus Type of Protection "8" 79-8 (1969) Electrical Apparatus for Explosive Gas Atmospfieres. Part 8: Classification of (vlaximum Surface Temperatures

80 (1964) Fixed Capacitors tor Direct Current Using Im- pregnated Paper or Paper/Plastic Film Dielectric (Agrees with €83.11-1968)

81 (1961) Specification for Tubular Fluorescent Lamps for General Lighting Service 82 (1962) Ballasts for Fluorescent Lamps,

(C82.1-1968. C82.2-1963, and C82.3-1962) Amendment 1 (1965) 83 (1957) Standards tor Plugs and Socket-Outlets for Domestic and Similar General Use (Agrees with C73.10-, .75-, .21-. .23-,

.26-. and .27-1966. Partially agrees with C73. 11-1966 and 0 73.25-1966) 84 (1957) Recommendations for fvlercury-Arc Converters,

(C34. 1-1958) 84A (1966) fvlercury-Arc Inverters, Supplement to Publication

84, 84B (1967) fVlercury-Arc Converters, Supplement to Publication

84, 85 (1957) Recommendations for the Classification of IVIaterials, for the Insulation of Electrical fvlachinery and Apparatus in Relation to their Thermal Stability in Service

86-1 (1962) Primary Cells and Batteries, Part 1: General, (C18 1-1965) Amendment 1 (1965) 86-2 (1963) Primary Cells and Batteries, Part 2: Specification Sheets, (CIS. 1-1965} Amendment 1 (1965) 86-3 (1965) Primary Cells and Batteries, Part 3: Terminals,-

(C18. 1-1965) Amendment 1 (1967) 88 (1957) Standard Rated Currents (2 to 63 Amperes) of Fuse

Links for Low Voltage Fuses 90 (1957) Recommendations for the Dimensions of Polarized Plugs for Hearing Aids 91 (1958) Recommended tvlethods of fvteasurement on Receivers for Frequency-fi^odulation Broadcast Transmission (076. 72- 7949 (R1961))

92-1 (1964) Electrical Installations in Ships, Part 1; General Requirements

92-2 (1965) Electrical Installations in Ships, Part 2; Graphical Symbols

92-3 (1965) Electrical Installations in Ships, Part 3; Cables

(Construction, Testing, and Installations)

Amendment 1 (1969) 92-4 (1965) Electrical Installations in Ships, Part 4: Switchgear,

Electrical Protection, Distribution, and Controlgear 92-5 (1965) Electrical Installations in Ships, Part 5: Trans- formers for Power and Lighting, Semiconductor Rectifiers, Generators (with Associated Prime-fVlovers) and tvlotors. Electric Propulsion Plant, Tankers

92-6 (1965) Electrical installations in Ships, Part 6: Accessories, Lighting, Accumulator (Storage) Batteries, Heating and Cooking Appliances, Internal Communications, Lightning Conductors 93 (1958) Recommended (ulethods of Test for Volume and

Surface Resistivities of Electrical Insulating f^aterlals (C59.3-

7 968i 94 (1968) Magnetic Tape Recording and Reproducing Systems: Dimensions and Characteristics 95-1 (1961) Lead-Acid Starter Batteries, Part I; General Re- quirements and fvlethods of Test 95-2 (1965) Lead-Acid Starter Batteries, Part II: Dimensions of Batteries 95-3 (1963) Lead- Acid Starter Batteries, Part III: Dimensions and l^rtarkings of Terminals

I EC No.

96-1 (1962) Radio-Frequency Cables, Part I: General Re- quirements and Measuring Methods,

Amendment 1 (1965) Amendment 2 (1966) 96-1A (1964) Supplement to Publication 96-1. 96-2 (1961) Radio-Frequency Cables, Part II: Relevant Cable

Specifications, 96-2A (1965) Supplement to Publication 96-2 96-2B (1966) Supplement to Publication 96-2, 97 (1967) Fundamental Parameters for Printed Wiring Techniques 98 (1964) Processed Disk Records and Reproducing Equip- ment, Amendment 1 (1967) 99-1 (1958) Recommendations for Lightning Arresters, Part 1: Non-Linear Resistor Type Arresters, (C62.1- 1967) 99-1A (1965) Supplement to Publication 99-1, 99-2 (1962) Lightning Arresters, Part II: Expulsion-Type Light- ning Arresters (C62. 1-1967) 100 (1962) Recommended Methods for the Measurement of Direct Inter-Electrode Capacitances of Electronic Valves and

Tubes, fC60.6-7959J Amendment 1 (1969), 101 (1958) Rules tor Auxiliary Machines on Motor Vehicles

(Electric Motors and Generators) 102 (1958) Rules lor the Electric Transmission of Vehicles with Diesel Engines (Main DC Motors and Generators) 103 (1969) Aluminum Electrolytic Capacitors for Long Life (Type

1) and for General Purpose Application (Type 2) 104 (1958) Recommendations for an International Specification

for Aluminum Alloy Conductor Wire of the Aluminum-Magnesium-Silicon Type

105 (1958) Recommendations for Commercial-Purity Aluminum

Busbar Material (C7. 27-1964) 106 (1959) Recommended Methods of Measurement of Radiation from Receivers for Amplitude-Modulation and Television Broadcast Transmissions, 106A (1962) Supplement to Publication 106 107 (1960) Recommended Methods of Measurements on Receivers for Television Broadcast Transmissions 108 (1967) Ceramic Dielectric Capacitors Type 1 109 (1959) Recommendations for Fixed Non-Wirewound Resist- ors Type 2, Amendment 1 (1962), 110 (1959) Recommendations for Power Capacitors for Fre- quencies Between 100 and 20,000 Hz (c/s)

111 (1959) Recommendation for the Resistivity of Commercial Hard-Drawn Aluminum Electrical Conductor Wire (C7. 20-1960) 112 (1959) Recommended Method for Determining the Comparative Tracking Index of Solid Insulating Materials Under

Moist Conditions 113 (1959) Classification and Definitions gf Diagrams and

Charts Used in Electrotechnology 114 (1959) Recommendation for Heat-Treated Aluminum Alloy Busbar Material of the Aluminum-Magnesium-Silicon Type. 115 (1959) Recommendations for Fixed Non-Wirewound Resist- ors Type 1 for Use in Electronic Equipment,

Amendment 1 (1963) Amendment 2 (1965) Amendment 3 (1968)

1 d6 (1959) Recommendations for Receiver-Type Metallized Mica Capacitors for Use in Electronic Equipment

117-1 (1960) Recommended Graphical Symbols, Part 1 : Kind of Current, Distribution Systems, Methods of Connection, and

Circuit Elements, Amendment 1 (1966) Amendment 2 (1967)
lEC AND ELECTRICAL ENGINEERING STANDARDS 57

I EC No. 117-2 (1960) Recommended Graphical Symbols, Part 2: Machines, Transformers, Primary Cells, and Accumulators,

Amendment 1 (1966), 117-3 (1963) Recommended Graphical Symbols, Part 3: Contacts, Switchgear, Mechanical Controls. Starters, and Elements

of Electromechanical Relays, (1966), (Y32. 2-1 967) Amendment 1 (1966) 117-4 (1963) Recommended Graphical Symbols, Part 4: Measuring Instruments and Electric Clocks 117-5 (1963) Recommended Graphical Symbols, Part 5; Generating Stations and Substations, Lines for Transmission and

Distribution 117-6 (1964) Recommended Graphical Symbols, Part 6; Variability, Examples of Resistors. Elements of Electronic Tubes.

Valves, and Rectifiers, (Y32.2- 1967) Amendment 1 (1966), Amendment 2 (1967) 117-7 (1966) Recommended Graphical Symbols, Part 7: Semiconductor Devices, Capacitors (Agrees with Y32. 2-1967)

117-8 (1967) Recommended Graphical Symbols, Part 8; Symbols for Architectural Diagrams

117-9 (1968) Recommended Graphical Symbols. Part 9: Tele- phony. Telegraphy, and Transducers 117-10 (1968) Recommended Graphical Symbols, Part 10: Aerials (Antennas) and Radio Stations (Y32. 2-1967) 117-11 (1968) Recommended Graphical Symbols, Part 11: Microwave Technology

117-12 (1968) Recommended Graphical Symbols. Part 12: Frequency Spectrum Diagrams

118 (1959) Recommended Methods for Measurements of the Electro-Acoustical Characteristics of Hearing Aids (S3. 3-1960) 119 (1960) Recommendations for Polycristalline Semi-conductor Rectifier Stacks and Equipments 120 (1960) Recommendations for Ball and Socket Couplings ol String Insulator Units 121 (1960) Recommendation for Commercial Annealed Aluminum Electrical Conductor Wire (07.23-1965)

122-1 (1962) Quartz Crystal Units for Oscillators. Section 1: Standard Values and Conditions: Section 2 Test Conditions:

Amendment 1 (1967) Amendment 2 (1969) 122-2 (1962) Quartz Crystal Units for Oscillators. Section o: Guide in the Use of Quartz Oscillator Crystals.

Amendment 1 (1969) 122-3 (1962) Quartz Crystal Units for Oscillators, Section 4 Standard Outlines, 122-3A (1968) Supplement to Publication 122-3, 123 (1961) Recommendations for Sound Level Meters (SI i- 1961) 124 (1960) Recommendations for the Rated Impedances and Dimensions of Loudspeakers 125 (1961) General Classification of Ferromagnetic Oxide

Materials and Definitions of Terms,

Amendment 1 (1965) Amendment 2 (1968) 126 (1961) lEC Reference Coupler for the Measurement of Hearing Aids Using Earphones Coupled to the Ear by Means of Ear Inserts (S3.3-7960; 127 (1962) Cartridge Fuse Links for Miniature Fuses 128 (1961) International Code for the Designation of Photo- graphic Projector Lamps

129 (1961) Alternating-Current Isolators (Disconnectors) and

Earthing Svxitches,

Amendment 1 (1963), 129A (1968) Supplement to Publication 129,

I EC No, 130-1 (1962) Connectors for Frequencies Below 3 MHz (Mc/s),

Part 1 : General Requirements and Measuring Methods,

Amendment 1 (1964) 130-1A (1968) Supplement to Publication 130-1

130-2 (1965) Connectors for Frequencies Below 3 MHz (Mc/s),

Part 2: Connectors for Radio Receivers and Associated Sound

Equipment. Amendment 1 (1969) 130-3 (1965) Connectors for Frequencies Below 3 MHz (Mc/s),

Part 3: Battery Connectors

130-4 (1966) Connectors for Frequencies Below 3 MHz (Mc/s),

Part 4: Circular Multipole Connectors with Threaded Coupling 130-5 (1966) Connectors for Frequencies Below 3 MHz (Mc/s),

Part 5: Rectangular Multipole Connectors with Blade Contacts 130-6 (1965) Connectors for Frequencies Below 3 MHz (Mc/s),

Part 6: Rectangular Miniature Multipole Connectors with Blade Contacts

130- 8 (1969) Connectors for Frequencies Below 3 MHz (Mc/s),

Part 8: Concentric Connectors for Audio Circuits in Radio

Receivers

131-1 (1962) Toggle Switches, Part 1: General Requirements and Measuring Methods

131-2 (1963) Toggle Switches, Part 2: Requirements for Toggle

Switches, Type 1

1 31-3 (1969) Lever Switches, Part 3: Requirements for Switches

of Type 2. Quick Make, Quick Break (Toggle Switches) 132- 1 (1962) Rotary Wafer Switches (Low Current Rating). Part

1 : General Requirements and Measuring Methods

132-2 (1963) Rotary Wafer Switches (Low Current Rating). Part

2: Rotary Wafer Switches with Central Mounting.

132-2A (1965) Supplement to Publication 132-2.

132-3 (1963) Rotary Wafer Switches (Low Current Rating). Part

3: Rotary Wafer Switches with Two-Hole Mounting, " i132-2A (1965) Supplement to Publication 132-2,

132-4 (1966) Rotary Wafer Switches (Low Current Rating), Part

4: Rotary Water Switches with Central Mounting; Maximum 12

Positions; Maximum Diameter 40mm

132-5 (1966) Rotary Wafer Switches (Low Current Rating), Part

5: Rotary Wafer Switches with Two-Hole Mounting; Maximum 26

Positions; Maximum Diameter 60mm

133 (1967) Dimensions for Pot-Cores Made of Ferromagnetic Oxides and Associated Parts. 134 (1961) Rating Systems for Electronic Tubes and Valves and

Analogous Semiconductor Devices (1961) 135 (1961) Numbering of Electrodes and Designation of Units in Electronic Tubes and Valves (1961) 136-1 (1962) Dimensions of Brushes and Brush-Holders for Electrical Machinery, Part 1: Principal Dimensions and Toler- ances (C64. 1-1963) 136-2 (1967) Dimensions of Brushes and Brush-Holders for Electrical Machinery, Part 2: Complementary Dimensions of Brushes. Terminations of Brushes (C64. 1-1963) 137 (1962) Bushings for Alternating Voltages Above 1,000 V

(C76.1-1964)

138 (1962) Methods of Measurement of Essential Electrical Properties of Receiving Aerials in the Frequency Range from 30 MHz (Mc/s) to 1,000 MHz (Mc/s),

138-A (1963) Supplement to Publication 138, 139 (1962) Preparation of Outline Drawings of Oscilloscope and

Picture Tubes 140 (1962) Glassware for Lighting Fittings 141-1 (1963) Tests on Oil-Filled and Gas-Pressure Cables and

Their Accessories, Part I: Oil-Filled, Paper-Insulated, Metal- Sheathed Cables and Accessories for Alternating Voltages up to 275 kV, Amendment 1 (1967)
58 ENGINEERING STANDARDS

I EC No

141-2 (1963) Tests on Oil-Filled and Gas-Pressure Cables and

Their Accessories. Pari II Internal Gas-Pressure Cables and

Accessories for Alternating Voltages up to 275 kV. including

Amendment 1 (1967) 141-3 (1963) Tests on Oil-Filled and Gas-Pressure Cables and

The.r Accessories, Part III: External Gas-Pressure (Gas Compression) Cables and Accessories lor Alternating Voltages up to 275 kV. Amendment 1 (1967), 142 (1962) Magnetic Sound Recording on 16mm and 35mm Film

for the International Exchange of Television Programmes

143 (1963) Series Capacitors lor Power Systems

144 (1963) Degrees of Protection of Encln«icros for Low-Voltage

Switchgear and Controlgear 145 (1963) Var-Hour (Reactive Energy) Meters 146 (1963) Monocrystalline Semiconductor Rectifier Cells, Stacks, Assemblies, and Equipments

147-0 (1966) Essential Ratings and Characteristics of Semiconductor Devices and General Principles of Measuring Methods. Part O: General and Terminology,

147-OA (1969) Supplement to Publication 147-0

147-1 (1963) Essential Ratings and Characteristics of Semiconductor Devices and General Principle of Measuring Methods,

Part 1 Essential Ratinos and CharacteiibiiCo.

147-1A (1963) Supplement to 147-1, 147-1B (1969) Supplement to 147-1 and 147-1A, 147-2 (1963) Essential Ratings and Characteristics of Semiconductor Devices and General Principles of Measuring Methods, Part 2. General Principles of Measuring Methods, including

147-2A (1969) Supplement to 147-2, 148 (1969) Letter Symbols for Semiconductor Devices and

Integrated Microcircuits 149-1 (1963) Sockets for Electronic Tubes and Valves, Part I: General Requirements and Methods of Test 149-2 (1965) Sockets for Electronic Tubes and Valves. Part II: Specification Sheets for Sockets and Dimensions of Wiring Jigs and Pin Straiqhteners.

149-2A (1968) Supplement to Publication 149-2 149-2B (1969) Supplement to Publication 149-2 150 (1963) Testing and Calibration of Ultrasonic Therapeutic Equipment

151-0 (1966) Measurements of the blectrical Properties of Electronic Tubes and Valves. Part 0: Precautions Relating to Methods of Measurement of Electronic Tubes and Valves

151-1 (1963) Measurements of the Electrical Properties of Electronic Tubes and Valves. Part I: Measurement of Electrode Current 151-2 (1963) Measurements of the tiectrical Properties of Electronic Tubes and Valves. Part II: Measurement of Heater or Filament Current 151-3 (1963) Measurements of the Electrical Properties of Electronic Tubes and Valves. Part III: Measurement of Equivalent Input and Output Admittances

151-4 (1963) Measurements of the Electrical Properties of Electronic Tubes and Valves, Part IV: Methods of Measuring

Noise Factor 151-5 (1964) Measurements of the Electrical Properties of Electronic Tubes and Valves, Part V: Methods of Measuring Hiss and Hum

151-6 (1965) Measurements of the Electrical Properties of Electronic Tubes and Valves, Part VI: Methods of Application of Mechanical Shock (Impulse) Excitation to Electronic Tubes and

Valves 151-7 (1964) Measurements of the Electrical Properties of Electronic Tubes and Valves, Part VII: Measurement of Equivalent Noise Resistance (060.9-1964)

I EC No

151-8 (1966) Measurements of the Electrical Properties of Electronic Tubes and Valves, Part VIII: Measurement of Cath- ode Heating Time and Heater Warm-Up Time

151-9 (1966) Measurements of the Electrical Properties of Electronic Tubes and Valves. Part IX: Methods of Measuring the Cathode- Interface Impedance

151-10 (1966) Measurements of the Electrical Properties of Electronic Tubes and Valves, Part X: Methods of Measurement

of Audio-Frequency Output Power and Distortion fC60. 75-7963) 151-11 (1966) Measurements of the Electrical Properties of Electronic Tubes and Valves, Part XI: Methods of Measurement

of Radio-Frequency Output Power (Agrees with C60. 15-1963) . . 151-12 (1966) Measurements of the Electrical Properties of Electronic Tubes and Valves. Part XII: Methods of Measuring

Electrode Resistance. Transconductance. Amplification Factor, Conversion Resistance, and Conversion Transconductance (C60 75-796.?) 151-13 (1966) Measurements of the Electrical Properties of Electronic Tubes and Valves, Part XIII: Methods of Measure- ment of Emission Current from Hot Cathodes for High-Vacuum

Electronic Tubes and Valves (C60. 15-1963) 151-14 (1968) Measurements of the Electrical Properties of Electronic Tubes and Valves, Part X.V Methods of Measurement

of Radar and Oscilloscope Cathode-Ray Tubes

151-15 (1967) Measurements of the Electrical Properties of Electronic Tubes and Valves, Part XV: Methods of Measurement

of Spurious and Unwanted Electrode Currents 151-16 (1968) Measurements of the Electrical Properties of Electronic Tubes and Valves. Part XVI: Methods of Measurement

for Television Picture Tubes

151-17 (1969) Measurements of the Electrical Properties of Electronic Tubes and Valves. Part XVII: Methods of Measure- ment of Gasfilled Tubes and Valves 151-18 (1968) Measurements of the Electrical Properties of Electronic Tubes and Valves, Part XVIII: Methods of Measure- ment of Noises Due to Mechanical or Acoustic Excitations 151-19 (1969) Measurements of the Electrical Properties of Electronic Tubes and Valves, Part XIX: Methods of Measurement

on Corona Stabilizers 151-20 (1969) Measurements of the Electrical Properties of Electronic Tubes and Valves, Part XX. Measurement of Thyrat- ron Pulse Modulators 152 (1963) Identification by Hour Numbers of the Phase

Conductors of 3-Phase Electric Systems

153-1 (1964) Hollow Metallic Waveguides, Part I: General Requirements and Measuring Methods

153-2 (1964) Hollow Metallic Waveguides, Part II: Relevant

Specifications for Ordinary Rectangular Waveguides, including Amendment 1 fC83 70-7963) Amendment 1 (1968). sold separately 153-3 (1964) Hollow Metallic Waveguides. Part III: Relevant

Specifications for Flat Rectangular Waveguides

153-4 (1964) Hollow Metallic Waveguides, Part IV: Relevant

Specifications for Circular Waveguides. (083 19-19581 Amendment 1 (1968) 153-5 (1968) Hollow Metallic Waveguides, Part V: Relevant

Specifications for Rectangular Waveguides with Circular Outside Cross-Section 153-6 (1967) Hollow Metallic Waveguides. Part VI: Relevant

Specifications for Medium Flat Rectangular Waveguides

154- 1 (1964) Flanges for Waveguides. Part I: General Re- quirements and Measuring Methods

154-2 (1968) Flanges for Waveguides. Part II: Relevant Specifi- cation for Flanges for Ordinary Rectangular Waveguides

154-3 (1968) Flanges for Waveguides. Part III: Relevant

Specifications for Flanges for Flat Rectangular Waveguides

154-4 (1969) Flanges for Waveguides, Part IV: Relevant Specifi- cations for Flanges for Circular Waveguides

155 (1963) Glow Starters for Tubular Fluorescent Lamps

(C78. 180-1966). Amendment 1 (1965)
lEC AND ELECTRICAL ENGINEERING STANDARDS 59

lEC No. 156 (1963) Method for the Determination of the Electric Strength

of Insulating Oils 157-1 (1964) Low-Voltage Distribution Switchgear, Part 1: Circuit-Breakers, (C37.T3-1963,

C37. 15-1954 (R1967). C37. 16-1963, and C37. 17-1 962) 157-1 A (1966) Supplement to Publication 157-1, ol 158-1 (1964) Low-Voltage Controlgear for Industrial Use, Part I: Contactors. 159 (1964) Dimensions of the Mating Parts of Radio- Frequency

Connectors 160 (1963) Standard Atmospheric Conditions for Test Purposes

161 (1965) Capacitors for Radio Interference Suppression

1 62 (1965) Lightng Fittings for Tubular Fluorescent Lamps

163-1 (1968) Sensitive Switches, Part I: General Requirements and Measuring Methods

154 (1964) Recommendations in the Field of Quantities and

Units Used in Electricity . 165 (1963) Rules for the Testing of Electric Rolling Stock on Completion of Construction and Before Entry into Service 166 (1965) Fixed Metallized Paper Dielectric Capacitors for Direct Current 167 (1964) Method of Test for the Determination of the

Insulation Resistance of Solid Insulating Materials (C59. 3-1968) 168 (1964) Tests on Indoor and Outdoor Post Insulators for Systems with Nominal Voltages Greater than 1000 V (C29.7- 1961 and C29.9-1961I

169-1 (1965) Radio-Frequency Connectors, Part I: General Requirements and Measuring Methods

169-2 (1965) Radio-Frequency Connectors, Part 2: Coaxial Unmatched Television Aerial Feeder Connector

169-3 (1965) Radio-Frequency Connectors, Part 3: Two Pin Connector for Twin Balanced Aerial Feeders. 169-4 (1967) Radio-Frequency Connectors, Part 4: R. F. Coaxial Connectors for Cables 96 I EC 50-12 170 (1964) Class 1.0 Alternating-Current Watthour Meters

171 (1964) Fundamental Parameters ol Connectors for Printed Wiring Boards, Amendment 1 (1969), 172 (1966) Test Procedure for the Evaluation of the Thermal Endurance of Enamelled Wire by the Lowering of the Electric Strength Between Twisted Wires 173 (1964) Colours of the Cores of Flexible Cables and Cords 174 (1966) AC Electric Pedestal Type Fans and Regulators. 175 (1965) AC Electric Table Type Fans and Regulators. 176 (1966) AC Electric Ceiling Type Fans and Regulators 177 (1965) Pure Tone Audiometers for General Diagnostic Purposes (Z24. 5-1951) 178 (1965) Pure Tone Screening Audiometers (Z24. 12-1952) 179 (1965) Precision Sound Level Meiers 180 (1965) Nominal Cross-Sectional Areas and Composition of Circular Copper Conductors for Rubber or Polyvinyl Chloride

Insulated Cables and Flexible Cords with a Rated Voltage Not Exceeding 750V

181 (1964) Index of Electrical Measuring Apparatus Used in Connection with Ionizing Radiation, Supplements 181-A and 181-B Amendment 1 (1967) , .>;olrt s- 181-A (1965) Supplement to Pub. 181 181-B (1966) Supplement to Pub. 181 182-1 (1964) Basic Dimensions of Winding Wires, Part I: Diameters of Conductors for Round Winding Wires. 182-2 (1964) Basic Dimensions of Winding Wires. Part II; Maximum Overall Diameters of Enamelled Round Winding Wires 183 (1965) Guide to the Selection of High-Voltage Cables 184 (1965) Methods for Specifying the Characteristics of Electro-Mechanical Transducers for Shock and Vibration Measurements 185 (1966) Current Transformers 186 (1969) Voltage Transformers. 187 (1965) Ceramic Dielectric Capacitors Type 2 188 (1965) Schedule for High-Pressure Mercury V ipour Lamps

(C7B. 1301-1968. C 78. T 305- 7 968, C78. 1308-1968. C78.1309-

1968. 078.1310-1968. and C78. 1311-1968)

I EC No. 189-1 (1965) Low-Frequency Cables and Wires with P.V.C.

Insulation and P.V.C. Sheath, Part 1: General Test and Measuring Methods

189-2 (1965) Low-Frequency Cables and Wires with P.V.C.

Insulation and P.V.C. Sheath, Part 2: Cables in Pairs, Triples, Quadruples, and Quintuples for Telephone and Telegraph Ex- changes, Amendment 1 (1965) Amendment 2 (1969) 189-3 (1967) Low-Frequency Cables and Wires with P.V.C.

Insulation and P.V.C. Sheath, Part 3: Equipment Wires, Type 1, with Solid or Stranded Conductor, P.V.C. Insulated, Single 189-4 (1968) Low-Frequency Cables and Wires with P.V.C.

Insulation and P.V.C. Sheath, Part 4: Distribution Wires with

Solid Conductors, P.V.C. Insulated, in Pairs, Triples, Quadruples, and Quintuples 189-5 (1969) Low-Frequency Cables and Wires with P.V.C.

Insulation and P.V.C. Sheath, Part 5: Equipment Wires and

Cables with Solid or Stranded Conductors, P.V.C. Insulated, Screened, Single or One Pair 190 (1966) Non-Wirewound Potentiometers Type 2 191-1 (1966) Mechanical Standardization of Semiconductor

Devices, Part 1 ; Preparation of Drawings of Semiconductor

Devices, (C37. 40-1962 through

C37. 47-1962) 191-1A (1969) Supplement to Publication 191-1, sold separately 191-2 (1966) Mechanical Standardization of Semiconductor

Devices, Part 2: Dimensions,

191-2A (1967) Supplement to Publication 191-2 (1966),

191-2B (1969) Supplement to Publications 191-2 and 191-2A,

192 (1965) Schedule for Sodium Lamps (Integral Type)

193 (1965) International Code for Model Acceptance Tests of Hydraulic Turbines 194 (1965) Terms and Definitions for Printed Circuits,

1 95 (1 965) Method of Measurement of Current Noise Generated

in Fixed Resistors. 196 (1965) I EC Standard Frequencies 197 (1965) High-Voltage Connecting Wire with Flame Retarding

Insulation for Use in Television Receivers 198 (1966) International Code for the Field Acceptance Tests of Storage Pumps

199 (1965) Dimensions of Lead- Acid Motor Scooter Batteries 200 (1966) Methods of Measurement of Loudspeakers

201 (1965) Power Sources for Portable Prospecting Equipment

for Radioactive Materials 202 (1965) Polyester Film Dielectric Capacitors for Direct Current 203 (1966) Dimensions of the Crimp Area of Machined Crimp Type Contacts

204-1 (1965) Electrical Equipment of Machine-Tools, Part 1: Electrical Ecuioment of Machines for General Use,

Amendment 1 (1967), 204-2 (1967) Electrical Equipment of Machine-Tools, Part 2: Electrical Equipment of Machines Used in Large Series Production Lines

,

204-3 (1968) Electrical Equipment of Machine-Tools, Part 3: Electronic Equipment of Machine-Tools 205 (1966) Calculation of the Effective Parameters of Magnetic

Piece Parts, 205A (1968) Supplement to Publication 205, 206 (1966) Designation of the Quantities Characterizing the Magnetic and Electric Properties of Vacuum and a Substance 207 (1966) Aluminum Stranded Conductors (C7. 21-1965) 208 (1966) Aluminum Alloy Stranded Conductors (Aluminum

Magnesium - Silicon Type) 209 (1966) Aluminum Conductors, Steel-Reinforced (C7.22- 1965) 210 (1966) Aluminum Alloy Conductors, Steel-Reinforced

422-764 OL - 71 - 5
60 ENGINEERING STANDARDS

I EC No. 211 (1966) Maximum Demand Indicators, Ciass 1.0 212 (1966) Standard Conditions for Use Prior to and During the Testing of Solid Electrical Insulating Materials 213 (1966) Tests on Solid-Core Insulators for Overhead Electric Traction Lines with a Voltage Greater Than 1000 V

214 (1966) On-Load Tap-Changers

215-1 (1966) Safety Requirements for Radio Transmitting Equip- ment. Part 1; Requirements

215-2 (1967) Safety Requirements (or Radio Transmitting Equip- ment. Part 2: Test Methods 216 (1966) Guide for the Preparation of Test Procedures for Evaluating the Thermal Endurance of Electrical Insulating Materials 217 (1967) Electronic Voltmeters 218 (1 966) Guide for th* Drafting of Performance Specifications

for Cores of Tuned Transformers and Inductors of Ferromagnetic Oxides for Telecommunication 219 (1966) Guide tor the Drafting of Performance Specifications

tor Cores of Broad-Band Transformers of Ferromagnetic Oxides

for Telecommunication

220 (1966) Dimensions of Tubes. Pins and Rods of Ferromagnetic Oxides

221 (1966) Dimensions of Screw Cores Made of Ferromagnetic

Oxides. Amendment 1 (1968) 222 (1966) Methods (or Specifying the Characteristics of Auxiliary Equipment (or Shock and Vibration Measurement

223 (1966) Dimensions of Aerial Rods and Slabs of Ferromagnetic Oxides 224 (1966) Marking of Control Settings on Hearing Aids 225 (1966) Ociave. Half-Octave, and Third-Octave Band Filters Intended for the Analysis of Sounds and Vibrations (SI. 11-1966) 226 (1967) Dimensions of Cross Cores (X-Cores) Made o( Ferromagnetic Oxides and Associated Parts 227 (1967) Polyvinyl Chloride Insulated Flexible Cables and Cords with Circular Conductors and a Rated Voltage Not Exceeding 750 V Amendment 1 (1969) 228 (1966) Nominal Cross-Sectional Areas and Composition o( Conductors o( Insulated Cables 229 (1966) Tests on Anti-Corrosion Protective Coverings of Metallic Cable Sheaths 230 (1966) Impulse Tests on Cables and Their Accessories 231 (1967) General Principles of Nuclear Reactor In- strumentation 232 (1966) General Characteristics of Nuclear Reactor In- strumentation 233 (1967) Tests on Large Hollow Porcelains for Use in Electrical Installations 234 (1967) Dimensions of Ceramic Dielectric Capacitors of the

Plate Type

235-1 (1967) Measurement of the Electrical Properties of Microwave Tubes and Valves, Part 1: General Terms and

Definitions 236 (1967) Methods for the Designation of Electrostatic Deflecting Electrodes of Cathode-Ray Tubes 237 (1967) Ignitrons To Be Used in Welding Machine Control 238 (1967) Edison Screw Lampholders 239 (1967) Nominal Dimensions of Cylindrical Machined Graphic Electrodes with Threaded Sockets and Connecting Pins for Use in Electric Arc Furnaces 240 (1967) Characteristics of Electric Infra-Red Emitters for Heating Purposes

241 (1968) Fuses for Domestic and Similar Purposes 242 (1967) Standard Frequencies for Centralized Network

Control Installations 243 (1967) Recommended Methods of Test tor Electric Strength

of Solid Insulating Materials at Power Frequencies

244-1 (1968) Methods of Measurement for Radio Transmitters,

Part 1 : General Conditions of Measurement, Frequency, Output Power, and Power Consumption,

244-1 A (1968) Supplement to Publication 244-1,

I EC No. 244-2 (1969) Methods of Measurement (or Radio Transmitters,

Part 2: Bandwidth, Out o( Band Power, and Power of NonEssential Oscillations,

•244-2A (1969) Supplement 1 to Publication 244-2 2^4-28 (1969) Supplement 2 to Publication 244-2 215 (1967) Rubber Insulated Flexible Cables and Cords with Circular Conductors and a Rated Voltage Not Exceeding 750 V,

Amendment 1 (1969), 246 (1967) Connecting Wires Having a Rated Voltage of 20 kV

and 25 kV DC and a Maximum Working Temperature of 105° C

for Use in Television Receivers 247 (1967) Recommended Test Cells for Measuring the Resistivity of Insulating Liquids and Methods of Cleaning the Cells ?48 (1967) External Diameter of Planchets Used in Nuclear

Electronic Instruments. 249-1 (1968) Metal-Clad Base Materials for Printed Circuits, Part 1: Test Methods 250 (1969) Recommended Methods for the Determination of the

Permittivity and Dielectric Dissipation Factor of Electrical In- sulating Materials at Power, Audio and Radio Frequencies,

including Metre Wavelengths

251-1 (1968) Methods of Test (or Winding Wires, Part 1: Enamelled Round Wires 252 (1967) AC Motor Capacitors 253 (1967) Power Supply (or Air and Land Vehicle-Mounted

Prospection Equipment (or Radioactive Materials 254 (1967) Lead-Acid Traction Batteries 255-1 (1967) Electrical Relays. Part 1: Instantaneous All-Or- Nothing Relays (C37. 1-1962 (R1967)) 256 (1967) External Diameters o( Cylindrical Radiation Probes

Containing Geiger-Muller or Proportional Counter Tubes or

Scintillation Detectors 257 (1968) Fuse-Holders lor Miniature Cartridge Fuse-Links 258 (1968) Direct Recording Electrical Measuring Instruments and Their Accessories 259 (1968) Miscellaneous Lamps and Ballasts (C78 Series) 260 (1968) Test Enclosures of Non-Injection Type tor Constant

Relative Humidity 261 (1968) Sealing Test (or Pressurized Waveguide Tubing and

Assemblies 262 (1969) Ballasts (or High Pressure Mercury Vapour Lamps

(082.4-1968. C82 5-1966. 082 6-1965. and C82.7-1963) 263 (1968) Scales and Sizes (or Plotting Frequency Characteristics 264-1 (1968) Packaging o( Winding Wires, Part 1 : Containers for Round Winding Wires 264-2 (1968) Packaging of Winding Wires, Part 2: Delivery Spools lor Winding Wires 265 (1968) High Voltage Switches (C37. 30-1962. C37. 31-1962, C37. 32-1965. C37. 33-1962, C37. 34-1962, and C37. 35-1962),

265A (1969) Supplement to 265, '265B (1969) Supplement to 265. 266 (1969) Fixed Wirewound Resistors Type 2 267 (1968) Guide to the Testing of Circuit-Breakers with Respect to Out-o(-Phase Switching 268- 1 (1968) Sound System Equipment. Part 1: General 269- 1 (1968) Low-Voltage Fuses with High Breaking Capacity

for Industrial and Similar Purposes. Part 1; General Requirements 270 (1968) Partial Discharge Measurements

271 (1969) Preliminary List of Basic Terms and Definitions for the Reliability of Electronic Equipment and the Components (or Parts) Used Therein 272 (1968) Preliminary Reliability Considerations 273 (1B88) Dimensions of Indoor and Outdoor Post Insulators and Post Insulator Units for Systems with Nominal Voltages

Greater Than 1000 V (C29.8-1961 and C29 9-1961) 274 (1968) Tests on Insulators of Ceramic Material or Glass for Overhead Lines with a Nominal Voltage Greater Than 1000 V

rC29. 7-7967)
lEC AND ELECTRICAL ENGINEERING STANDARDS 61

I EC No. 275 (1968) Polystyrene Film Dielectric Capacitors 276 (1968) Definitions and Nomenclature for Carbon Brushes.

Brush-Holders, Commutators, and Slip-Ring (Agrees with C64. 1- 1963) 277 (1968) Definitions for Switchgear and Controlgear

(C37. 100-1966 and C42. 25-1 956) 278 (1968) Documentation To Be Supplied with Electronic Measuring Apparatus 279 (1969) Measurement of tne Winding Resistance of an A. C. Machine during Operation at Alternating Voltage 280 (1968) Class 0.5 Alternating-Current Watthour Meters

281 (1969) Magnetic Cores for Application in Coincident Current

Matrix Stores Having a Nominal Selection Ratio of 2:1 282-1 (1968) High-Vottage Fuses. Part 1: Current-Limitina Fuses 283 (1968) Methods for the Measurement of Frequency and

Equivalent Resistance of Unwanted Resonances of Filter Crystal Units 284 (1968) Rules of Behaviour with Respect to Possible Hazards When Dealing with Electronic Equipment and Equipment Employing Similar Techniques 286 (1968) Packaging of Components on Continuous Tapes 287 (1969) Calculation of the Continuous Current Rating of Cables (100% Load Factor)

>288-1 (1969) Tube and Valve Shields, Part 1: General Re- quirements and Methods of Test /288-2 (1969) Tube and Valve Shields, Part 2: Specification Sheets for Shields for Tubes and Valves and Dimensions of Testing Devices and Gauges for Shields (057.12.00-1968. C57. 12. 90-1968, and C57. 16-1958) 289 (1968) Reactors (C57.12. 00-1968. C57. 12.90-1968. C57.16-1958) 290 (1969) Evaluation of the Thermal Endurance of Electrical Insulating Varnishes by the Helical Coil Bond Test 291 (1969) Fuse Definitions (C37.40 through C37. 47-1962) »292-1 (1969) Low-Voltage Motor Starters, Part 1: Direct-on-Line

(Full Voltage) AC Starters 293 (1968) Supolv Voltages for Transistorized Nuclear In- struments

> 294 (1969) Measurement of the Dimensions of a Cylindrical Component Having Two Axial Terminations ,295 (1969) DC Periodmeters; Characteristics and Test Methods 296 (1969) Specification for New Insulating Oils for Trans- formers and Switchgear 297 (1969) Dimensions of Panels and Racks (for Nuclear

Electronic Instruments) (C83. 9-1968) 299 (1969) Measurement of the Performance Characteristics of Electric Blankets 300 (1969) Managerial Aspects of Reliability 301 (1969) Preferred Diameters of Wire Terminations of Capacitors and Resistors 304 (1969) Standard Colours for P.V.C. Insulation for Low- Frequency Cables and Wires (C83.1-1969)

I EC No. „305 (1969) Characteristics of String Insulator Units of the Cap

and Pin Type (C29. 2-1962 (R1969)) 307 (1969) Electric Fans and Regulators for Use in Ships
52 ENGINEERING STANDARDS

TABLE 11. Original Length Unit in lEC Recommendations

Original length unit U.S. participated

in voting

1955-1961 1962-1969

Number Percent * Number Percent *

A. All metric Yes 8

1 34.8

8.7

40

23

29.9

17.2

B. Metric dominant

No

Yes

10

8

1

43.5

34.8

4.3

63

36

7

47.1

26.9

5.2

C. Mixed

No

Yes

9

4

0

39.1

17.4 0

43

104

32.1

7.5 3.0

D. Inch dominant

No

Yes

4

0

A0

17.4

0AU

14

7

1

10.5

5.2 0.7

E. All inch

No

Yes

0

0

0

0

0

0

8

5

1

5.9

3.7 0.7

Total

No

0 0 6 4.4

23 134

* Percent of total.
lEC AND ELECTRICAL ENGINEERING STANDARDS

TABLE 12. International Electrical Standards Having Length Units

I EC

Rec.

Original

length

unit *

U.S. (ANSI)

U.K.

(BS)

Germany

(DIN)

Japan

(JIS) India

(IS) France (AFNOR)

41 B 353 1948

-

45 B 132 B8101

HO ts IDA DO I AA l^ Oo. I S8 J JO p 1 on 1 V. 1 UU 1 1 o / u

JSSJ 1I A\ 55-2 A 692 56-4 n1 > \^ J f

1 1 (\ 60 Q r68 1 Cll 1 2071

fii \j I R r 1

)

C7709

Oil

61 -2 DB

61-3 B

64 A 161 49810 C7501, 7517 418

65 A 415 616

67 D 448 (5) yj f C7104 2684

68-2-6 /\ 40046/8 C50''5 C90-163

58_2-7 C90- 1 65 5g_2-i

C5028

68-2-1

3

;\ C5029 2 106 C93_001

68-2-17 40046/1 5 C503

589 r9'?-001 V„ 7 J —\J\J 1 68-2-20 \ 40046/ 1 8 589 C93-001

68-2-2

A 40046/19 C5035 589 C93-001

68-2-27 B C0912 C90-180

68-2-29 B C90-I62

72-1 c C50.8 3979 (6) 1231 72-2 B 3979 (6) 2223

74 B 148 C2101 335 76 B C57.12 C4301, 4305 2026 C52-100

78 C 3040

79 C 229 C0901, 0903 2148 79-4 B 4056

79-6 A

79-7 A

81 c 1853 49862 C7601 2418 C72-210

82 B C82.1, C82.2

C82.3

2818 (7) C8101 1534

83 c (2) 546, 1363 49440-1 C8302 1293 86-2 A C18.1 (8) (12) 86-3 A C18.1 397 (8) 92-1 B 89001 92-3 C 89001 C3410

93 C C59.3 2782 C6481 3396

94 B (9) C5509, 5550

5551 4377

95-2 A 3911 7231 1/1-12 95-3 A 7231 1/1-12
64 ENGINEERING STANDARDS

TABLE 12. International Electrical Standards Having Length

Units — Con.

I EC Original U.S. U.K. Germany Japan India France

Rec. length

unit * (ANSI) (BS) (DIN) (J IS) (IS) (AFNOR)

96-2 A 2316

97 B 40801 C50I0

98 C 1928 45536-7,

45546-7

C8502

99-2 C C62.I 3070, 485( 100 D C60.6 C7111 4096

103 B 2134 41230, 41240

41332

C5140, 641

6440, 6451

4317

104 B 48200/6

106 A 905 45300 4546

108 B 2133A 41920 C6422 1980

109 B 2112 C6401, 6406 2903

111 B C7.20 215, 2627 48200/5

114 B 2898 1748/1, 43670

115 B 2112 44050, 44052 C6406, 6401 2902

116 B 2132 41 120 C644I 2001

118 A S3.

45600 C5512 3641

121 A C7.23 2627 4800

122-3 E (10) 124 A C5515 2382

126 A S3.

3171 42601 C55I2 3641

130-1 A 3826

130-2 A

130-3 B 45315,45316 2926

130-4 B

130-5 B 41622

130-6 B 41618

131-1 A 3452

131-2 B

131-3 D

132-1 A 41619, 41631 2628

132-3 B 41619, 41631

132-4 B

132-5 B 41631

133 B 4061 41293, 41294 C25I6

136-1 E C64.I (11) 3003 C5 1-902 136-2 B C64.1 3003 C5 1-902

140 B 364 40450, 49999 C7708

141-1 A C3607

141-2 A C3608

141-3 A

142 D 2981 15552, 15655, 15687

149-2 D 41557/1, 2, 6 41559/1, 2, 6 3354

149-2A B 149-2B
lEC AND ELECTRICAL ENGINEERING STANDARDS 65

TABLE 12. International Electrical Standards Having Length

Units — Con.

Original

length

unit *

U.S. (ANSI)U.K.

(BS)

Germany

(DIN)

Japan

(JIS) India

(IS) France (AFNOR)

BA

BE

BD

C

D

BD

BBA

C

B

BE

B

BA

A

A

A

A

A

A

A

A

A

A

A

A

A

C

C

A

E

B

C83.10

C83.19

2135 3820

380

3361

2133

C7.21

C7.22

215

3242

215

47302

47302

47302/2

44424

41170

45317

46435

46435

41920

41871, 41879

48200/5.

48201/5.

48202/1

48200/6

48201/6

48202/3

48202, 48204

4493

C6504, 6506

C7601, 7602

C3003

C9601

C9601

C3102-3

C3202-3,

3210-1

C6422

C3005

2959

3723

1913, 1777

1169 555 2982 4800

4800

2786

D5302

C3109

5001 5000

1 145

398

C34-125

398 I C34-120
66 ENGINEERING STANDARDS

TABLE 12. International Electrical Standards Having Length

Units — Con.

Original U.K. Germany Japan India France

Rec. length

unit * (ANSI) (BS) (DIN) (JIS) (IS) (AFNOR)

T 1 f\ 1 1 u AA 4oZUZ, 4o4U0 /"I/I 1 *> <: l_ j4— 1 Z J AA

1 Z J 1 J lib AA 4 1 Z / / , 41 Z 7 V/

227 694

228 cV 234 \

238 A 98 C8302

239 A

245 A 7. 4180 C3302 694

246 A

248 A 3775 44423

250 A 4486 C26-230

25 1-1 A 46453 C3003 4800

256 A 44422

257 A

259 B

264-1 A 46396 C3205

264-2 A

273 c C66-037

286 B C93-720

288-1 A

288-2 E

294 A C5102. 5202 C93-013

297 A C6010

299 C

301 A C5001

305 A

307 A

,*A. all metric; B. metric dominant: C, mixed; D, inch dominant; E, all inch.

United States (ANSI)

(1) C8 1.51, .101, .102. .103. .104. .105, . 106. . 107, . 108. . 109 and . 1 1 1

(2) C73.10, .15, .21, .23, .26 and .27. Partially agrees with C73.I 1 and C73.25. United Kingdom (BS) f

(3) 52, 98, 1 164, 1875. Germany (DIN)

(4) 49663, 49665, 49675, 49680, 49685, 49710, 49715, 49729, 49740.

(5) 41534, 41536-41539. 41549. 41544-41547. 41551. 41601, 41603. 41605, 51607,

44431.

(6) 42671-42673, 42676-42679, 42681, 42946, 42948, 42973.

(7) 49665, 49710, 49715, 49729, 49740.

(8) 40856, 40855, 40869, 40870. 40875.

(9) 45511, 45513, 45515. 45517.

(10) 451 1 I. 451 13, 451 17. 451 18. (11) 43000,43008,43021,43028,43040,43042.

India (IS) (12) 203, 267, 556, 586, 2576.
16. ISO RECOMMENDATIONS

The International Organization for Standardization (ISO) is concerned

with standardization in all fields except electricity which is the responsibility

of lEC. Since its organization in 1948, 139 technical committees have been

established. Additional ones are being established each year. Thus far, there

is no committee for pharmaceuticals and drugs; but in the field of health and

safety there are committees dealing with anesthetic and breathing equipment, athletic equipment, dentistry, food, medical syringes, protective

clothing and equipment for personal safety, stretchers, and transfusion

equipment. Most of the committees deal with industrial materials and equipment including such products as aircraft, agricultural machines, automobiles,

computers, earth moving machines, office machines, and shipbuilding. The

work of a technical committee results in an ISO Recommendation or an ISO

Standard. An ISO Recommendation requires approval of a majority of the

member countries participating in the technical committee and 60 percent of

the member countries of ISO that voted either positively or negatively. An

ISO Standard requires that no member body of ISO objects to transforming an ISO Recommendation into an ISO Standard.

The Secretariats of ISO technical committees, subcommittees and working groups are distributed among 29 member countries shown in figure 4. The predominance of the United Kingdom and France in number of

Secretariats held is very striking. Together, they have 420 or over 40 percent

of the 1,010 total. Germany has 128 and the United States has 99. Thus,

these four countries have nearly two-thirds of the Secretariats. The

remainder are distributed among 25 countries, mainly Sweden (41), Netherlands (38), USSR (36), Italy (33), Belgium (30), and Switzerland (28). The

industrial Western European countries hold nearly 75 percent of the

Secretariats, Eastern European countries hold about 8 percent, the U.S.

holds about 1 0 percent, and all other regions combined hold about 4 percent.

67
68 ENGINEERING STANDARDS

FIGURE 4

DISTRIBUTION OF ISO SECRETARIATS

AUSTRALIA

AUSTRIA

BELGIUM

BRAZIL

CANADA

CZECHOSLOVAKIA

DENMARK

FINLAND

FRANCE

GERMANY

HUNGARY

INDIA IRAN

ISRAEL

ITALY

JAPAN

NETHERLANDS

NORWAY

POLAND

PORTUGAL

ROMANIA

SOUTH AFRICA

SPAIN

SWEDEN

SWITZERLAND

UNITED KINGDOM

USA

USSR

YUGOSLAVIA

mTECHNICAL COMMITTE

im SUBCOMMITTEES

WORKING GROUPS

CD TOTAL

ES

50 100 150 200

NUMBER OF SECRETARIATS

Secretariats for seven subcommittees and 43 working groups are not yet al- located. In view of the advantages associated with a Secretariat, it is not sur- prising that most ISO Recommendations are based on national standards of

European countries.

The ISO Recommendations that were issued from 1951 through 1969 are

listed in table 13. If those issued in two or more parts are considered as a

separate recommendation for each part, about 1 ,200 ISO Recommendations

are in this list. The time period between initiation of work by the Technical

Committee and its issuance as an ISO Recommendation is 5 years or more.

After issuance, they are reviewed at least every 5 years. Thus far, 37 of the

ISO Recommendations listed are revisions.

These 1 ,200 ISO Recommendations are a small percentage of the number

of national standards in industrial countries. Nevertheless, even this number
ISO RECOMMENDATIONS 69

is too large to compare with national standards in this survey in view of the

limited funds and manpower available. Therefore, this survey is restricted to a comparison of ISO Recommendations with national standards for the fol- lowing industrial materials and products which were selected to be representative of the status of international standardization and the role of measure- ment units in such standardization:

For each of these groups, there are sufficient ISO Recommendations to be

indicative of the problems involved and the achievements in harmonizing national standards.

Materials Products Ferrous metal (steel) Non-ferrous metal

Plastics Rubber

Antifriction bearings

Building construction Pipe and tubing Screw threads and fasteners
70 ENGINEERING STANDARDS

TABLE 13. Numerical List— ISO Recommendations

Ref. Title RI -1951 Standard reference temperature for industrial length measurements R2 -1966 Designation of the direction of twist in textile yarns and related products, 2nd Edition, replacing R2-1951 and R2/A1 1961 R3 -1953 Preferred numbers. Series of preferred numbers R4 -1953 International code for the abbreviation of titles of periodicals

R5 -1954 Diffuse transmission density

R6 -1954 Method for determining photographic speed and exposure index R7 -1954 Pipe threads for gas list tubes and screwed

fittings where pressure-tight joints are made

on the threads (V» inch to 6 inches) R8 -1954 Layout of periodicals

R9 -1968 International system for the transliteration of

Slavic Cyrillic characters, 2nd Edition

Errata Errata of first printing Sept. 1968 RIO -1954 Aircraft connection for ground air-conditioning

Rll -1954 Aircraft pressure cabin ground test connection R12 -1955 Identification of aircraft pipe-lines

R13 -1955 Cast iron pipes, special castings and cast iron

parts for pressure main lines R13/A1 Amendment 1 to ISO Recommendation R 13- -1968 1955 R14 -1955 Straight-sided splines (for cylindrical shafts). Nominal dimensions in millimetres R15/I Rolling bearings. Radial bearings. Boundary

-1968 dimensions. General plan. Part 1. Diameter

series 8, 9,0, 1,2,3 and 4, 2nd Edition R16 -1955 Standard tuning frequency (Standard musical

pitch) R17 -1955 Guide to the use of preferred numbers and of

series of preferred numbers

R17/A1 Amendment 1 to ISO Recommendation R 17- -1966 1955 R18 -1955 Short contents list of periodicals or other documents

R19 -1956 Deckbolts R20 -1956 Rivets for hatches R21 -1956 Sprocket wheels R22 -1956 Widths of flat transmission belts and corre- sponding pulleys

R23 -1956 Emulsion and sound record positions in camera for 35 mm sound motion picture film R24 -1956 Emulsion and sound record positions in pro- jector for 35 mm sound motion picture film R25 -1956 Emulsion position in camera for 16 mm silent motion picture film R26 -1956 Emulsion position in projector for direct front projection of 16 mm silent motion picture

film R27 -1956 Emulsion and sound record positions in camera for 16 mm sound motion picture film R28 -1956 Emulsion position in camera for 8 mm silent motion picture film R29 -1956 Emulsion position in projector for direct front projection of 8 mm silent motion picture film R30 -1956 Bibliographical strip

Erratum R31/II

-1958

R31/1II

-1960

R31/IV

-1960

R31/V

-1965 R31/VII

-1965 R31/XI

-1961 R32 -1957 R32/A1

-1966

R33 -1957

Erratum E

Erratum F

Erratum F2 R34 -1957

Ref. Title R31/I Basic quantities and units of the International -1965 System of units (SI units) 2nd Edition, replacing R 3 1/1-1956

Erratum of first printing December 1 965 Quantities and units of periodic and related phenomena

Quantities and units of mechanics

Quantities and units of heat

Quantities and units of electricity and magnetism

Quantities and units of acoustics

Mathematical signs and symbols for use in physical sciences and technology

Identification of medical gas cylinders

Amendment 1 to ISO Recommendation R 32-

1957 Du Pont constant load method of measuring

abrasion resistance of vulcanized natural and synthetic rubbers

Erratum of first printing. Nov. 1961

Determination of tear strength of vulcanized

natural and synthetic rubbers (crescent test piece)

R35 -1957 Determination of the mechanical stability of

latex R36 -1969 Determination of the adhesion strength of vul- canized rubbers to textile fabrics, 2nd Edition R37 -1968 Determination of tensile stress-strain properties of vulcanized rubbers, 2nd Edition R38 -1957 Bollards (vertical type) with and without lugs R39 -1957 Anchor chains. Lugless joining shackles, Kenter

type R40 -1957 Anchor chains. Studless links R41 -1957 Covers for deck openings for 220 mm pumps

R42 -1957 Mushroom ventilators R43 -1957 Aircraft jacking pads

R44 -1957 Directions of operation of toggle switches on

aircraft R45 -1957 Aircraft pressure refuelling connections R46 -1957 Aircraft fuel nozzle grounding plugs and sockets R47 -1957 Aircraft toilet flushing and draining connections

R4J^ -1968 Determination of hardness of vulcanized rubbers, 2nd Edition R49 -1957 Malleable cast iron pipe fittings screwed in ac- cordance with ISO Recommendation R 7 R50 -1957 Steel sockets screwed in accordance with ISO

Recommendation K 7. Minimum lengths R51 -1957 Pipe-lines for the transport of combustible

liquids. Nominal diameters R52 -1957 Grooved pulleys for V-belts. Groove secfions A, B, C, D, E

R53 -1957 Basic rack of cylindrical gears for general

engineering

R54 -1966 Modules and diametral pitches of cylindrical gears for general engineering and for heavy

engineering, 2nd Edition, replacing R 54-1957
ISO RECOMMENDATIONS 71

TABLE 13. Numerical List — ISO Recommendations — Continued

Ref. Title R55 -1957 Specification for seedlac R56 -1957 Specification for shellac R56/A1 Amendment 1 to ISO Recommendation

-1966 R 56-1957

R57 -1957 Specification for bleached lac R58 -1958 Substances of paper R59 -1958 Determination of the percentage of acetone

soluble matter in phenolic mouldings

R60 -1958 Determination of apparent density of moulding

material that can be poured from a specified funnel R61 -1958 Determination of apparent density of moulding

material that cannot be poured from a specified funnel R62 -1958 Determination of water absorption

R62/A1 Amendment 1 to ISO Recommendation R 62-

-1965 1958 R63 -1958 Lengths of flat transmission belts R64 -1958 Steel tubes — Outside diameters (larger than -Add. 419 mm (16.5 in)) 1969 R65 -1958 Steel tubes suitable for screwing in accordance

with ISO Recommendation R 7 R66 -1958 Paper vocabulary. First series of terms (English,

French, Russian)

R66/A1 Amendment 1 to ISO Recommendation

-1964 R 66-1958

R66/A2 Amendment 2 to R66-1958

-1968 R67 -1958 Muscovite mica blocks, thins and films. Methods

for grading by size R68 -1969 ISO General purpose screw threads— Basic

profile- 2nd Edition R69 -1958 Dimensions for 16 mm motion-picture film with perforations along one and two edges

R70 -1958 Photographic sound record on 35 mm prints R71 -1958 Photographic sound record on 16 mm prints R72 -1958 Sound records and scanning area of 35 mm

double width push-pull sound prints. Normal

and offset centerline types R73 -1958 Image produced by camera aperture and pro- jected image area for 35 mm films R74 -1958 Image produced by camera aperture and pro- jected image area for 8 mm films R75 -1958 Determination of temperature of deflection under load R76 -1958 Ball and roller bearings. Methods of evaluating

static load ratings R77 -1958 Bibliographical references. Essential elements R78 -1968 Guide on the form for standards for chemical

products and for methods of chemical analysis, 2nd Edition R79 -1968 Brinell hardness test for steel, 2nd Edition R80 -1968 Rockwell hardness test (B and C scales) for

steel, 2nd Edition R81 -1967 Vickers hardness test for steel (Load 5 to 100

kgf), 2nd Edifion R82 -1959 Tensile testing of steel R83 -1959 Charpy impact test (U-notch) for steel R84 -1959 Izod impact test for steel

Ref. R85 1959

R86 -1959

R87 - 1959

R88 - 1959

R89 - 1959 R90 - 1959

R91 - 1959 KVZ — 1 Q^Q

IN." J/

1

1963

R93/II 1969

R93/III 1969 R94 - 1959

R95 - 1959

R96 - 1959

R97 - 1959

R98 - 1959

R99 -1959

RlOO -1959

RlOl -1959

R102 -1959

R103 -1959

R104 -1966

R105/I

-1959

R105/A1

-1963 R105/I/A2

-1968

R105/II-1963

R105/III-1963 R105/IV

-1968

R105/V

-1969

R106 -1959

R107 -1959

R108 -1959

R109 -1968

Title Bend test for steel Tensile testing of steel sheet and strip less than

3 mm and not less than 0.5 mm thick Simple bend testing of steel sheet and strip less than 3 mm thick Reverse bend testing of steel sheet and strip less than 3 mm thick Tensile testing of steel wire Hermetically sealed metal food containers. General data: determination of capacity,

designation, marking, definitions, procedure

for dimensional specification Petroleum measurement tables Definition of side (left or right) of spinning

machinery

Cylindrical sliver cans 2nd Edition, replacing

R 93-1959

Cylindrical sliver cans. Heights over 1000 mm

Cylindrical sliver cans on castors

Spindle gauges for ring-spinning and ring- doubling frames

Rings for ring-spinning and ring-doubling frames

for <0 travellers (reversible) Rings for ring-spinning and ring-doubling frames

for -^C^ travellers (non-reversible) Rings for ring-spinning and ring-doubling frames

for ear-shaped travellers Diameters of drafting rollers for cotton, wool, spun silk and staple fibre Diameters of pulleys for flat transmission belts Crowns of pulleys for flat transmission belts Width of sheets of paper

Gravity filling orifices for aircraft Sizes and mounting dimensions of aircraft in- strument cases (rear-mounting type) Thrust bearings with flat seats. Boundary dimensions, 2nd Edition, replacing section 2 of R104-1959

Test for colour fastness of textiles. First series. {Former reference: R105-1959)

Amendment to the first edition.

Second amendment to the first edition

Tests for colour fastness of textiles. Second series Tests for colour fastness of textiles. Third series Tests for colour fastness of textiles. Fourth

Series Tests for colour fastness of textiles. Fifth series

Light metal rivets for shipbuilding. Nominal

diameters, rivet hole diameters and clearances

Light metal rivets for shipbuilding. Rivet heads Weaving looms. Definition of side (left or right) Weaving looms. Working width, 2nd Edition
72 ENGINEERING STANDARDS

TABLE 13. Numerical List— ISO Recommendations— Continued

Ref. Title RllO -1959 Paper cones for yarn winding (cross wound).

Taper 9° 15' Rill -1959 Paper cones for yarn winding (cross wound)

Taper 4° 20' R112 -1959 Paper cones for yarn winding (cross wound).

Taper 3° 30' R113 -1969 Rolling bearings. Accessories, 2nd Edition R114 -1959 Composition of 99.8 unalloyed magnesium

ingots

R115 -1968 Classification and composition of unalloyed

aluminum ingots for remelting, 2nd Edition R116 -1959 Common names for pesticides. First list (English, French, Russian)

R117 -1959 Determination of boiling water absorption R1 18 -1959 Determination of methanol-soluble matter in polystyrene

Erratum F R119 -1959 Determination of free phenols in phenolformaldehyde mouldings

R120 -1959 Determination of free ammonia and ammonium compounds in phenol-formaldehyde

mouldings

R121 -1959 Composition of magnesium-aluminum-zinc alloy castings

R122 -1959 Composition of magnesium-aluminum-zinc alloy ingots for casting purposes R123 -1968 Samplingoflatex, 2nd Edition R124 -1966 Determination of total solids of latex, 2nd Edition, replacing R 1 24- 1959 R 1 25 - 1 966 Determination of alkalinity of latex, 2nd Edition, replacing R 125-1959 R126 -1959 Determination of dry rubber content of latex R127 -1959 DeterminationofKOH number of latex R128 -1959 Engineering drawing. Principles of presentation

R129 -1959 Engineering drawing. Dimensioning

R130 -1959 Colour identification of mechanical control

circuits for aircraft R131 -1959 Expression of the physical and subjective magnitudes of sound or noise R132 -1959 Determination of resistance to flex cracking of vulcanized natural or synthetic rubber (De

Mattia type machine)

R133 -1959 Determination of resistance to crack growth of vulcanized natural or synthetic rubber (De

Mattia type machine)

R134 -1962 Non-screwed steel tubes for general purposes 2nd Edition, replacing R 134-1959 R135 -1959 Paper vocabulary. Second series of terms R135/A1 Amendment 1 to ISO Recommendation

-1964 R135-1959

R136 -1959 Simple torsion testing of steel wire R137 -1960 Determination of wool fibre diameter. Projection

microscope method

R138 -1960 Universal yarn count system

R139 -1967 Standard atmospheres for conditioning and testing textiles, 2nd Edition R140 -1960 Field and laboratory measurements of airborne and impact sound transmission R141 -1960 Pirn winders and cross winders. Definition of

side (left or right)

Ref.

R143 -1969

R144 -1960

R145 -1960

R146 -1968

Erratum R147 -1960

R148 -1960

tv 1 Hy 1 y\j\j

R150 -I960

R151 -1960

R152 -1960

R153 -1960

R154 -1960

R155 -1960

R156 -1967

R157 -1960

Errata E R158 -1960

Erratum R159 -1960

Errata E R160 -1960

R16i -1960

R162 -1960

R163 -1960

R164 -1960

Errata R165 -1960

R166 -1960

R167 -1960

R168 -1960

R169 -1960

R170 -1960

R171 -1961

R172 -1961

R173 -1961

R174 -1961

Title . - . Weaving preparatory machines. Definition of

side (left or right) Weft pirns for box-loaders for automatic looms.

Pirn tip dimensions. 2nd Edition Reverse bend testing of steel wire Wrapping test for steel wire

Verification of Vickers hardness testing machines, 2nd Edition

Erratum of first printing March 1 968 Load calibration of testing machines for tensile testing of steel Beam impact test (V-notch) for steel Modified Erichsen cupping test for steel sheet and strip Raw, refined and boiled linseed oil Marking of hatchway beams

Marking of wooden hatchway covers Ordinary glasses for scuttles and lights. Dimensions Marking of rolled, drawn and extruded products

in light metals or in light alloys for shipbuilding

details Limiting values for the adjustment of centres for transmission pulleys

Verification of Brinell hardness testing machines,

2nd Edition Determination of forms of sulphur in coal

Erratum of first printing. Nov. 1961 Determination of ash of hard coal

Erratum of first printing. Nov. 1961 Determination of total sulphur in coal by the Strambi method

Errata of first printing. Nov. 1961 Asbestos cement pressure pipes

Pipes of plastics materials for the transport of

fluids (Outside diameters and nominal pressures). Part I: Metric series Location of recording heads for three magnetic sound records on 35 mm film and one magnetic sound record on 17.5 mm film Magnetic striping of 16 mm film perforated

along both edges

Composition of aluminium alloy castings

Errata of first printing. Nov. 1961 Flanging test on steel tubes

Drift expanding test on steel tubes Bend test on steel tubes

Stretchers, stretcher carriers and hospital

trolleys. Dimensions

Sizes of photocopies (on paper) readable without

optical devices Anchor chains, stud links (common links, enlarged links, end links and joining shackles) Determination of bulk factor of moulding

materials Detection of free ammonia in phenolformaldehyde mouldings (qualitative method)

Determination of the percentage of styrene in polystyrene with Wijs solution Determination of viscosity number of polyvinyl- chloride resin in solution
ISO RECOMMENDATIONS 73

TABLE 13. Numerical List — ISO Recommendations — Continued

Ref. R175 -1961

R176 -1961

R177 -1961

R178 -1961

R179 -1961

Erratum E R180 -1961

R181 -1961

R182 -1961

R183 -1961

R184 -1961 R185 -1961 R185/A1

-1969

R186 -1968

R187 -1961

R188 -1961

R189 -1961 R190 -1961 R191 -1961

R192 -1961

R193 -1961

R194 -1961 R 194/ Add. 1 -1969

R194/P1

-1963 R194/CS

-1964

R194/D

-1964

R194/NL

-1968

R195 -1961

R196 -1961

R197 -1961 R198 -1961

R199/I

-1961

Title Determination of the resistance of plastics to chemical substances Determination of the loss of plasticizers from

plastics by the activated carbon method

Determination of migration of plasticizers from

plastics Determination of flexural properties of rigid plastics Determination of the Charpy impact resistance of rigid plastics (Charpy impact flexural test) Erratum of first printing. June 1961 Determination of the Izod impact resistance of

rigid plastics (Izod impact flexural tests) Determination of incandescence resistance of

rigid self-extinguishing thermosetting plastics Determination of the thermal stability of polyvinyl chloride and related copolymers and

their compounds by the Congo red method

Determination of the bleeding of colourants from plastics Brinell hardness test for grey cast iron Classification of grey cast iron Amendment 1 to ISO Recommendation R 185-

1961 Method of sampling paper and board for testing, 2nd Edition Method for the conditioning of paper and board

test samples

Accelerated ageing or simulated service tests on

vulcanized natural or synthetic rubbers

Principles of operation of standards marks

Tensile testing of light metals and their alloys

Brinell hardness test for light metals and their alloys Vickers hardness test for light metals and their alloys Microcopies on transparent bases. Sizes of rec- ommended bases

List of equivalent terms used in the plastics in- dustry (English, French, Russian)

Second supplement to list of equivalent terms used in the plastics industry (will be merged

with Draft ISO Recommendation No. 751)

Appendix PI: Corresponding Polish terms

Appendix Cs: Corresponding Czech terms

Appendix D: Corresponding German terms

Appendix NL: Corresponding Dutch terms

Drift expanding test on copper and copper alloy tubes Method of mercurous nitrate test for copper and

copper alloys Classification of coppers Double-dick flat pallets for through transit of goods

Thrust ball bearings with flat seats. Normal

tolerances

Ref. Title R199/II Rolling bearings. Thrust ball bearings with flat -1968 seats. Tolerances. Part 2 — Tolerances classes

6, 5 and 4 R200 -1961 Internal clearance in unloaded bearings. Definitions R201 -1961 Radial internal clearance in unloaded radial groove type ball bearings with cylindrical bore. Values R202 -1961 Flattening test on steel tubes R203 - 1 96 1 Interrupted creep testing of steel at elevated temperatures (load and temperature interrupted)

R204 - 1 96 1 Non-interrupted creep testing of steel at elevated temperatures

R205 -1961 Determination of proof stress and proving test for steel at elevated temperatures

R206 -1961 Creep stress rupture testing of steel at elevated temperatures

R207 -1961 Composition of 99.95 unalloyed magnesium

ingots

R208 -1961 Composition of aluminium alloy castings (complement to R 164) R209 -1968 Composition of wrought products of aluminium

and aluminium alloys. Chemical composition

(per cent), 2nd Edition R210 -1961 Essential oils. Packing

R21 1 -1961 Essential oils. Labelling and marking containers R212 -1961 Essential oils. Sampling

R213 -1961 Lathe tool posts (overall internal height)

R214 -1961 Abstracts and synopses R215 -1961 Presentation of contributions to periodicals

R216 -1961 Trimmed sizes of writing paper and certain classes of printed matter R217 -1961 Method of expression of dimensions and direction of manufacture of unprocessed writing and printing paper R218 -1961 Microcopies. Scale of 35 mm microfilms for in- ternational exchange

R219 -1961 Common names for pesticides. Second list R219/A1 Amendment 1 to R2 19- 1961 -1968

R220 -1961 Method of sampling raw cotton for testing

R221 -1961 Steel tubes. Thicknesses R222 -1961 Voltages for aircraft electrical systems

R223 -1961 Safety features for ground power units for D.C.

aircraft servicing and engine starting R224 -1961 Standard form of declaration of performance of

aircraft electrical equipment

R225 -1961 Bolts, screws and studs. Dimensioning

R226 -1961 Normal equal-loudness contours for pure tones and normal threshold of hearing under free

field listening conditions R227 -1961 Single box pickers for automatic looms R228 -1961 Pipe threads where pressure-tight joints are not made on the threads (Vs inch to 6 inches) R229 -1961 Machine tool speeds and feeds R230 -1961 Machine tool test code

Errata F R23 1 -1961 Paper vocabulary. Third series of terms R232 -1961 Straight-sided splines and gauges. Dimensions in inches
74 ENGINEERING STANDARDS

TABLE 13. Numerical List — ISO Recommendations — Continued

Rcf. Title R233 -1961 International system for the transliteration of Arabic characters R234 -1961 Files and rasps. Lengths and cross sections R235 -1961 Parallel shank twist drills jobber and stub series and Morse taper shank twist drills Erratum E Erratum of first printing. Sept. 1962 R236 -1961 Hand reamers and long fluted machine reamers, Morse taper shank

Erratum E Erratum of first printing. Sept. 1962 Enatum E 2 Erratum 2 of first printing. Sept, 1962 R237 -1961 Diameters of shanks and sizes of driving squares

for rotating tools with parallel shanks

Erratum E Erratum of first printing. Sept. 1962 R238 -1961 Reduction sleeves and extension sockets for

tools with Morse taper shanks

Erratum E Erratum of first printing, Sept. 1962 R239 -1961 Drill chuck tapers R240 -1969 Interchangeability dimensions for milling cutters and cutter arbors or cutter mandrels- Metric

series and inch series — 2nd Edition R241 -1961 Shanks for turning and planing tools. Sections and tolerances R242 -1961 Carbide tips for turning tools. Metric series

Erratum Erratum of first printing, March 1964 R242-A1 Amendment 1 to ISO Recommendation R 242- -1966 1961 R243 -1961 Turning tools with carbide tips. Metric series R244 -1962 Aircraft sealing wire R245 -1962 Aircraft lockwire R246 -1962 Cylindrical roller bearings. Separate thrust collars. Boundary dimensions

Determination of ash in raw natural rubber Determination of volatile matter in raw natural rubber Determination of dirt in raw natural rubber Sampling of raw natural rubber Widths and lengths of conveyor belts Ply adhesion of conveyor belts Grooved pulleys for V-belts. Groove sections YandZ

Quality, machining and balancing of transmission pulleys Geometrical inspection of grooves of pulleys for V-belts Section checking of V-belts

Principles for the selection of common names for pesticides

Amendment 1 to ISO Recommendation R 257 Common names for pesticides. Third list Transliteration of Hebrew

Terms relating to microcopies and their bases ISO General purpose metric screw threads —

General plan — 2nd Edition ISO General purpose metric screw threads —

Selected sizes for screws, bolts and nuts —

2nd Edition R263 -1962 ISO inch screw threads. General plan and selection for screws, bolts and nuts (diameter range

0.06 to 6 in)

R247 -1962 R248 -1962

R249 -1962 R250 -1962 R251 -1962 R252 -1962

R253 -1962

R254 -1962

R255 -1962

R256 -1962 R257 -1962

R257/A1

-1968

R258 -1962 R259 -1962 R260 -1962 R261 -1969

R262 -1969

Ref. R264 -1962

R265 -1962

R266 -1962

R267 -1962

R268 -1962 R269 -1962

R270 -1962

R271 -1962

R272 -1968

R273/I

-1962

R273 -1962/

AI-1969

R273/1I

-1968

R274 -1962

R275 -1962 R276 -1962 R277 -1962 R278 -1962

R279 -1962

R280 -1962

R281 -1962

R282 -1962

R283 -1962

R284 -1962

R285 -1962 R286 -1962

Errata Erratum E R287 -1963

R288/I

-1963

R288/II

-1969

R289 -1963

R289/A1

1968

Title Pipes and fittings of plastics materials. Socket

fittings for pipes under pressure. Basic dimensions. Metric Series Pipes and fittings of plastics materials. Socket

fittings with spigot ends for domestic and

industrial waste pipes. Basic dimensions. Metric Series Preferred frequencies for acoustical measure- ments

Figures for aircraft instrument dials and number

plates Aircraft instrument dials and pointers Sizes of correspondence envelopes and pockets Determination of fibre length by measuring the

length of individual fibres Implementation of the Tex System for designating the size of textile fibres, yarns and similar structures Hexagon bolts and nuts. Widths across flats, heights of heads, thicknesses of nuts. Metric

series, 2nd Edition Clearance holes for metric bolts

Amendment I to ISO/R 273-1962

Clearance holes for metric bolts, 42 up to and

including 1 50 mm thread diameter Copper tubes of circular section. Dimensions:

Metric Series Zinc oxide Linseed stand oils and lithographic varnishes Raw tung oil Standard layout for methods of analysis of

essential oils Determination of the density and relative density of essential oils Determination of the refractive index of essential

oils Ball and roller bearings. Methods of evaluating

dynamic load ratings Sampling of conveyor belts Full thickness tensile strength and elongation of conveyor belts. Specifications and method of

test Electrical conductivity of conveyor belts. Specification and method of test Steel tubes. Butt welding bends (90° and 180°) ISO System of limits and fits. Part I: General,

tolerances and deviations

Errata of first printing. February 1964 Erratum No, 2 of first printing, February 1964 Method for the determination of moisture content of paper (Oven-drying method)

Slotted and castle nuts with metric thread

Slotted and castle nuts with metric thread, 42

up to and including 100 mm thread diameter Determination of viscosity of natural and synthetic rubbers by the shearing disk viscometer

First amendment to the first edition of ISO

Recommendation R289-1963
ISO RECOMMENDATIONS 75

TABLE 13. Numerical List — ISO Recommendations — Continued

Ref. Title R290 -1963 Common names for pesticides. Fourth list R291 -1963 Standard atmospheres for condition and testing R292 -1967 Plastics. Determination of the melt flow index

of polyethylene and polyethylene compounds,

2nd Edition R293 -1963 Compression moulding test specimens of thermoplastic materials R294 -1963 Injection moulding test specimens of thermoplastic materials R295 -1963 Compression moulding test specimens of thermosetting materials R296 -1963 Self-holding tapers for tool shanks R297 -1963 7/24 tapers for tool shanks

Errata Errata of first printing. October 1 966 R298 -1963 Lathe centres. Sizes for interchangeability

R298-Add. 1 Lathe centres. Centre angle

-1969

R299 -1963 T slots for machine tools R300/I ISO Identification code for rolling bearings. - 1 963 Group I : Radial ball and roller bearings. Group

II: Thrust ball and roller bearings. Group III: Tapered roller bearings, metric series R300/II ISO Identification code for rolling bearings. -1965 Group IV: Tapered roller bearings, inch series R300/III ISO identification code for rolling bearings:

-1968 Group V: Airframe bearings

R301 -1963 Zinc alloy ingots

R302 -1963 Determination of the Kappa number of pulp (Degree of deiignification) R303 -1963 Lighting and signalling for motor vehicles and

trailers R304 -1963 Surface active agents. Determination of surface

tension and interfacial tension R305 -1963 Determination of the thermal stability of polyvinyl chloride and related copolymers and their compounds by the discoloration method

R306 -1968 Plastics — Determination of the Vicat softening

temperature of thermoplastics, 2nd Edition R307 -1963 Determination of the viscosity number of poly- amides resins in dilute solution R308 -1963 Determination of the acetone soluble matter

(resin content of material in the unmoulded

state) of phenolic moulding materials R309 -1963 Methods of sampling manganese ores. Part I. — Ore loaded in freight wagons

R 310 to 323; Analysis of manganese ores R310 -1963 Determination of hygroscopic moisture R31I -1963 Determination of silicon dioxide R312 -1963 Determination of active oxygen (conventionally

expressed as manganese dioxide) R313 -1963 Determination of total iron content R314 -1963 Determination of carbon dioxide R315 -1963 Determination of nickel R316 -1963 Determination of cobalt R317 -1963 Determination of arsenic R318 -1963 Determination of aluminium oxide R319 -1963 Determination of total manganese content R320 -1963 Determination of sulphur

R321 -1963 Determination of phosphorus

R322 -1963 Determination of copper

Ref. Tide R323 -1963 Determination of lead R324 -1963 Cones for cross winding for dyeing purposes. Half angle of the cone 4° 20' R325 -1963 Wood cones for cross winding. Half angle of the cone 4° 20' R326 -1963 Wood cones for cross winding. Nominal half angle of the cone 5° 57' R327 -1963 Wood cones for cross winding. Half angle of the cone 3° 30' R328 -1963 Size of picture postcards and of lettercards R329 -1963 Large pallets for through transit of goods

R330 -1963 Pipes of plastics materials for the transport of

fluids (outside diameters and nominal pres- sures) Part II: inch series R331 -1963 Determination of moisture in the analysis sample

of coal by the direct gravimetric method

R332 -1963 Determination of nitrogen in coal by the Kjeldahl

method

R333 -1963 Determination of nitrogen in coal by the semi- micro Kjeldahl method

R334 -1963 Determination of total sulphur in coal by the Eschka method

R335 -1963 Determination of caking power of coal by the Roga method

R336 -1963 Plain end steel tubes, welded or seamless. General table of dimensions and masses per unit length

R337 -1963 Semi-trailer fifth wheel kingpin

R338 -1963 Lifeboats for less than one hundred people

R339 -1963 Definitions of terms appearing in ISO Recommendations for oils and pigments

R340 -1963 Flame resistance of conveyor belts. Specifications and method of test R341 -1963 Cotton spinning machinery. Working width R342 -1963 Worsted and woollen cards. Working width R343 -1963 Warp tubes for ring spinning and ring doubling

spindles. Inch dimensions, tolerances and

gauges R344/I Flyer bobbins -1963

Erratum Erratum of first printing September 1963 R344/II Flyer bobbins for spindle diameters of 25 mm or -1969 more and lifts of 300 mm and over R345 -1963 Tests on galvanized steel wire for ropes R346 -1963 Galvanized steel wire ropes R347 -1963 Anchor chains. End shackles R348 -1963 Determination of moisture in the analysis sample

of coal by the direct volumetric method

R349 -1963 Audibert- Amu dilatometer test for coal R350 -1963 Determination of chlorine in coal by the bombcombustion method

R351 -1963 Determination of total sulphur in coal by the high temperature combustion method

R352 -1963 Determination of chlorine in coal by the high

temperature combustion method

R353 -1963 Method of expression of dimensions of proc- essed writing paper and certain classes of

printed matter R354 -1963 Measurement of absorption coefficients in a reverberation room

422-764 OL - 71 - 6
76 ENGINEERING STANDARDS

TABLE 13. Numerical List — ISO Recommendations — Continued

Ref. Title Ref. R355/I Tapered roller bearings. Boundary dimensions. R388 -1964

-1963 Metric series: Diameter series 2 and 3. Inch

series: Lines 1 , 2, 3,4,R389 -1964

R355/II Tapered roller bearings. Boundary dimensions. -1965 Metric series: Extension of diameter series

2 and 3 R390 -1964

R355/III Tapered roller bearings. Boundary dimensions. R391 -1964

-1967 Part III. Metric series. Diameter series 9 and 0 R392 -1964

R355/IV Rolling bearings. Tapered roller bearings.

-1968 Boundary dimensions. Part 4 — Sub-units. Inch series R393 -1964

R355/V Rolling bearings — Tapered roller bearings- R394 -1964

-1969 Boundary dimensions— Part V: Sub-unitsMetric series R395 -1964

R356 -1963 Essential oils. Preparation of sample. Methods R396 -1964

of test R397 -1964

R357 -1963 Expression of the power and intensity levels of R398 -1964

sound or noise R399 -1964

R358 -1963 Maximum aspect ratio of projector aperture for projection of 35 mm non-anamorphotic mo- R400 -1964

tion-picture films R401 -1964

R359 -1963 Projected image area for 16 mm film R360 -1963 Location of recording heads for four magnetic R402 -1964

sound records on 35 mm film R403 -1964

R361 -1963 Basic ionizing radiation symbol R404 -1964

R362 -1964 Measurement of noise emitted by vehicles R405 -1964

R363 -1964 Flat steel healds for general use R406 -1964

R364 -1967 Twin wire healds for frame weaving, 2nd Edition R407 -1964

R365 -1967 Twin wire healds for Jacquard weaving, 2nd

Edition R366 -1967 Pitch bound reeds, 2nd Edition k408 -1964

R367 -1967 Metal reeds with plate baulk, 2nd Edition R409 -1964

R368 -1964 Warp tubes for ring spinning and ring doubling

spindles. Metric dimensions, tolerances and R410 -1964

gauges R369 -1964 Symbols for indications appearing on machine R411 -1964

tools R41 1/Al

Errata Erratum of first printing. December 1965 -1968 R370 -1964 Conversion of toleranced dimensions from

inches into millimetres and vice versa R412 -1965 R371 -1964 Terms relating to microcopy apparatus Errata R372 -1964 Paper vocabulary. Fourth series of terms R413 -1965 R373 -1964 General principles for fatigue testing of metals R414 -1965 R374 -1964 Ring expanding test on steel tubes R415 -1965 R375 -1964 Tensile testing of steel tube R376 -1964 Calibration of elastic proving devices R416 -1965 R377 -1964 Selection and preparation of samples and test pieces for wrought steel R417 -1965

R378 -1964 Parallel bars R379 -1964 Horizontal bar R418 -1965 R380 -1964 Rings

R381 -1964 Vaulting horse and pommelled horse R419 -1965 R382 -1964 Balancing beam

R383 -1964 Interchangeable conical ground glass joints R420 -1965 R384 -1964 Principles of construction and adjustment of volumetric glassware R421 -1965 R385 -1964 Burettes R386 -1964 Principles of construction and adjustment of

liquid-in-glass laboratory thermometers R422 -1965 R387 -1064 Principles of construction and adjustment of hydrometers Erratum

Title ISO metric series for basic thicknesses of sheet and diameters of wire Standard reference zero for the calibration of pure-tone audiometers Sampling and inspection of asbestos-cement

products

Building and sanitary pipes in asbestos-cement Asbestos-cement pipe fittings for building and

sanitary purposes Asbestos-cement corrugated sheets for roofing and cladding

Asymmetrical section corrugated sheets in asbestos-cement for roofing and cladding Asbestos-cement slates for roofing and cladding Asbestos-cement fiat sheets Wrapping test for copper and copper alloy wire Bend test for copper and copper alloys Vickers hardness test for copper and copper

alloys (Test loads from 2.5 to 50 kgf) Tensile test for copper and copper alloys Tensile test for copper and copper alloy tubes of

circular section Tensile test of copper and copper alloy wire

Brinell hardness test for copper and copper alloys General technical delivery requirements for steel Aircraft tow bar connections to tractors Inscription of linear and angular tolerances Yoke type valve connections for small medical

gas cylinders used for anaesthetic and resuscitation purposes

Safety colours Tables of Vickers hardness values (HV) for metallic materials Tables of Brinell hardness values (HB) for use in tests made on flat surfaces Common names for pesticides. Fifth list Amendment 1 to ISO Recommendation R411-

1964 — Common names for pesticides. Fifth

list Gum spirit of turpentine and wood turpentines

Errata of first printing. October 1966 Heads of aircraft lubricating nipples

Aircraft tyre valves Envelopes, postcards and similar articles. Cancellation area

Picture postcards. Area reserved for the address Methods for determining thiosulphate and

tetrathionate in processed black-and-white photographic film, plates and papers

Specification for photographic grade sodium

sulphite

Specification for photographic grade sodium

thiosulphate, crystalline Specification for photographic grade potassium

bromide

Method for indicating the stability of the images

of processed black-and-white films, plates and

papers

Specification for photographic grade p-methylaminophenol sulphate

Erratum of first printing, March 1965
ISO RECOMMENDATIONS 77

TABLE 13. Numerical List — ISO Recommendations — Continued

R457

R458

R459

R460

R461

R462

R463

R464

Errata R465

R466

R467

R468

R469

-1965

-1965

-1965

-1965

-1965

-1965

-1965

-1965

-1965

-1965

-1966

1966

1966

Ref. Title Ref. R423 -1965 Specification for photographic grade hydro- R455 -1965

quinone

R424 -1965 Specification for photographic grade sodium R456 -1965

carbonate, anhydrous

Erratum Erratum of first printing, March 1965 R425 -1969 Quantity packaging of sensitized photographic

materials 2nd Edition R426 -1965 Classification of brasses, leaded brasses, special brasses and high tensile brasses R427 -1965 Classification of tin bronzes and special tin bronzes R428 -1965 Classification of aluminium bronzes and special

aluminium bronzes R429 -1965 Classification of copper-nickel alloys R430 -1965 Classification of copper-nickel-zinc alloys R431 -1965 Specification for electrolytic copper wire bars, cakes, slabs, billets, ingots and ingot bars R432 -1965 Characteristics of construction of ply type con- veyor belts R433 -1965 Marking of conveyor belts R434 -1965 Lengths of Y-section V-belts (/p=5.3 mm or

0.21 in) R435 -1965 ISO conventional typographical character for

legibility tests (ISO character) R436 -1965 Informative labelling R437 -1965 Chemical analysis of steels. Determination of

total carbon (Gravimetric method after combustion in a stream of oxygen)

R438 -1965 Method for the determination . of the bulking

thickness and bulk of paper R439 -1969 Chemical analysis of steel and cast iron. Determination of total silicon (Gravimetric method), 2nd Edition R440 -1969 Shape, size and direction of operation of lever controls on aircraft 2nd Edition R441 -1965 Drop wires for mechanical and electrical warp

stop motions R442 -1965 Verification of pendulum impact testing machines for testing steels R443 -1965 Marking of aircraft gas cylinders

Erratum Erratum of first printing. September 1965 R444 -1965 Phlogopite mica blocks, thins and splittings. Methods for grading by size R445 -1965 Vocabulary of terms relating to pallets R446 -1965 Microcopies. Legibility tests. Description of the ISO mire (ISO test object) and its use in photographic document reproduction

R447 - 1 965 Direction of operation of machine tool controls R448 -1965 Marking of industrial gas cylinders for the identi- fication of the content R449 -1965 Magnetic compasses and binnacles. Class A, for use in sea navigation. Part I: General require- ments R450 -1965 Aircraft connection for water of drinkable quality

R451 -1965 Aircraft pressure re-oiling connection R452 -1965 Essential characteristics of 35 mm microfilm R483 -1966

reading apparatus

R453 (incorporated in R 862-1968)

R454 -1965 Relation between sound pressure levels of nar- R484

row bands of noise in a diffuse field and in a

frontally incident free field for equal loudness R485

R470 -1966

R471 -1966

R472

R473

R474

R475

R476

R477

R478

R479

R480

R481

R482

-1969 -1966

-1966

-1966

-1966

-1966

-1966

-1966

-1966

-1966 -1966

1966

1966

Title Analysis of soap. Determination of total crude

fatty acids Analysis of soap. Determination of free caustic

alkali Analysis of soap. Determination of chlorides Determination of stiffness in torsion as a function of temperature

Grooved pulleys for narrow V-belts. Groove sections SPZ, SPA, SPB

Lengths of narrow V-belts. Sections SPZ, SPA,

SPB

Connections for aircraft ground electrical supplies

Recommended practice for the determination

of change of mechanical properties after contact with chemical substances

Dial gauges reading in 0.01 mm, 0.001 in and

0.0001 in Bearings with locating snap ring. Dimensions

Errata of first printing. November 1 966 Double-row self-aligning roller bearings. Radial

internal clearance Image produced by camera aperture for 16 mm

films Preferred modules and diametral pitches of

cylindrical gears for general engineering Surface roughness

Dimensions and conductor resistance of general purpose electrical cables with copper conductors, for aircraft Dimensions and conductor resistance of heatresisting (190 °C) electrical cables with copper

conductors, for aircraft Standard atmospheres for the conditioning and

testing of rubber test pieces

Plastics. Definitions of plastics terms, 3d edition Lithopone Performance requirements for general purpose

electrical cables with copper conductors for

aircraft Dimensions of rectangular refractory bricks

Pirn winders. Terminology. Basic terms and

definitions Cone winders or cheese winders. Terminology.

Basic terms and definitions Paper. Untrimmed stock sizes for the ISO-A

series. ISO primary range

Paper. Untrimmed sizes. Designation. Tolerances

Perforated metal cheese centres for bast fibre yarns Warper's beams. Basic dimensions Numbering of aircraft engines, engine cylinders and combustion chambers, and direction of

engines and propellers

Plastics. Methods for maintaining constant rela- five humidity in small enclosures by means of aqueous solutions Shipbuilding details. Ship screw propellers. Manufacturing tolerances for casting and finishing Aircraft water-methanol pressure connections
78 ENGINEERING STANDARDS

TABLE 13. Numerical List — ISO Recommendations — Continued

R496 -1966

R497 -1966

R498 -1966

Ref. Title R486 -1966 Cutting and perforating dimensions for double8 mm motion-picture raw stock film R487 -1966 Steel roller chains type S 32 to S 88 with their associated chain wheels R488 -1966 Butyrometers for the determination of the per- centage of fat in milk by the Gerber method

R489 -1966 Plastics. Determination of the refractive index

of transparent plastics R490 -1966 Single magnetic sound stripe on 16 mm motionpicture film perforated along one edge

R491 -1966 Cutting and perforating dimensions for 35 mm

motion-picture raw stock film R492 -1966 Rolling bearings. Radial bearings. Tolerances R493 -1966 Dimensions for single-hole mounting, lever- operated switches for aircraft R494 -1966 Parallel shank twist drills long series R495 -1966 General requirements for the preparation of test codes for measuring the noise emitted by

machines

Shaft heights for driving and driven machines

Guide to the choice of series of preferred

numbers and of series containing more

rounded values of preferred numbers

Preparation of dry films from concentrated

natural rubber latex R499 -1966 Paper. Internal diameters of cores of reels R500 -1966 Power take-off and draw-bar for agricultural tractors R501 -1966 Determination of the crucible swelling number

of coal R502 -1966 Determination of the Gray-King coke type of coal R503 -1966 Composition of wrought magnesium-aluminiumzinc alloys R504 -1966 Turning tools with carbide tips. Designation and

marking

R505 -1966 Tear propagation resistance of the carcass of conveyor belts. ( Method of test) R506 -1966 Determination of volatile fatty acid number of

latex R507 -1966 Procedure for describing aircraft noise around

an airport

R508 -2966 Identification colours for pipes conveying fluids

in liquid or gaseous condition in land installa- tions and on board ships

R509 -1966 Principal dimensions of pallet trucks

Erratum Erratum of first printing, October 1 966 R510 -1966 Red lead R511 -1966 White lead R512 -1966 Sound signalling devices on motor vehicles. Acoustic standards and technical specifications

R513 -1966 Application of carbides for machining by chip removal. Designation of main groups of chip removal and groups of application

R514 -1966 Turning tools with carbide tips. Internal tools. (Metric series) R515 -1966 Dimensions for stereo still photography using 35 mm objectives on 35 mm film, 5-perforation format R516 -1966 Exposure-time markings for shutters used in

still cameras

Ref. R517 -1966

R518 -1966

R519 -1966

R520 -1966

R521 -1966

R522 -1966

R523 -1966

R524 -1966

R525 -1966

R525-Add. 1 -1969

R526 -1966

R527 -1966

R528 -1966

R529 -1966

Erratum R530 -1966

R531 -1966

Erratum R532 -1966

R533 -1966

R534 -1966

R535 -1966

R536 -1966

R537 -1966

Erratum R538 -1966

R539 -1966

R540 -1966

R541 -1966

R542 -1966

R543 -1966

R544 -1966

R545 -1966

R546 -1966

Title .

• Lens aperture markings for still cameras Camera accessory shoes Dimensions of small flash connections for hand-held cameras

Cereals and pulses: Determination of the mass

of 1000 grains

Machine chucking reamers with parallel shanks

or Morse taper shanks

Special tolerances for reamers Recommended range of outside daimeters for

milling cutters Hard metal wire drawing dies. Interchangeability dimensions of pellets and cases Bonded abrasive products — General factures (Designation- Ranges of dimensions— Profiles) Dimensions of the wheel holes special applications and tolerances

Significance to purchasers of marks indicating

conformity with standards

Plastics. Determination of tensile properties

Refractory products. Determination of pyrometric cone equivalent (Refractoriness) Short machine taps and hand taps

i Erratum of first printing, November 1 966 Dimensions for general purpose push-pull

single-pole circuit-breakers for aircraft Cast iron sanitary pipes and fittings for waste

water and ventilation

j Erratum of first printing, December 1966 Method for calculating loudness level Rolling bearings. Double row cylindrical roller bearings, type RD with tapered bore 1:1. Special requirement: tolerance class 5 Determination of the thickness of single sheets of paper Determination of the water absorption of paper

or board (Cobb method)

Determination of paper substance

Testing of plastics with the torsion pendulum

Erratum of first printing, January 1967 Conventional signs. To be used in schemes for

the installations of pipe-line systems in ships

Dimensions and conductor resistance of heatresisting (260 °C) electrical cables with copper

conductors for aircraft Determination of fusibility of fuel ash Measurement of fluid flow by means of orifice plates and nozzles Oilseeds — Sampling

Definition and marking of safety film for motionpicture uses (replacing Draft ISO Recommendation No. 83) Diameters and tolerances for electrodes for arc welding and filler metals for gas welding

Lengths and tolerances for filler rods, other than drawn or extruded, for welding

Lengths and tolerances for drawn or extruded

filler rods for welding, supplied in straight lengths

I
ISO RECOMMENDATIONS 79

TABLE 13. Numerical List — ISO Recommendations — Continued

Ref. R547 -1966

R548 -1966

R549 -1966

R550 -1966

R551 -1966

R552 -1966

R553 -1966

R554 -1966

R555 -1966

R556

R557

R558

•1967 1967 1967

R559 - 1967

R560 - 1967

R561 - 1967 R562 - 1967

R563 - 1967 R564 - 1967

R565 - 1967

R566 - 1967 R567 - 1967

R568 - 1967 R569 - 1967

R570 - 1967

R571 - 1967 R572 - 1967 R573 - 1967

R574 - 1967

R575 - 1967

R576 - 1967 R577/1

1967

R577/11 1968

Title Lengths and tolerances of electrodes for the welding of mild steel and low alloy high

tensile steel Methods of chemical analysis of manganese ores. Determination of barium oxide content Methods of chemical analysis of manganese ores. Determination of combined water content Methods of chemical analysis of manganese ores. Determination of titanium content Methods of chemical analysis of manganese ores. Determination of zinc content Methods'of chemical analysis of manganese ores. Det^mination of calcium oxide content and magnesium oxide content Methods of chemical analysis of manganese ores. Determination of vanadium content Standard atmospheres for conditioning and/or

testing. Standard reference atmosphere.

Specifications

Liquid flow measurement in open channels. Dilution methods for measurement of steady flow. Part 1 — Constant rate injection method

Determination of the micum indices of coke

Symbols, dimensions and layout for safety signs

Conditioning atmosphere. Test atmosphere. Reference atmosphere. Definitions

Steel pipes for gas and water, and for sewage, welded or seamless Cold drawn precision steel tubes. Metric series. Dimensions and masses per metre

Graphical symbols for coal preparation plant Determination of the volatile matter of hard

coal and of coke

Knife sections of mower cutter bars Designations, diameters and breaking strengths of preformed stranded steel cables for aircraft controls Woven wire cloth and perforated plates in test sieves. Nominal sizes of apertures Common names for pesticides. Sixth list Determination of the bulk density of coke in a

small container Heald frames for single or double row of healds Heald frames. Dimensions in relationship with

pitch of the harness Heald carrying rods. Coordination with end

loops of the healds Metal reeds with double-spring baulk

Shuttles for pirn changing automatic looms Dobby lags and pegs in wood, metal or other

suitable material Perforated parallel tubes for cheese dyeing.

(Dimensions in millimetres) Transfer cones for dyeing purposes. Half-angle

at top of cone 4°20' Paper patterns for dobbies Tapered roller bearings. Tolerances. Metric

series. Part 1: Normal tolerances

Rolling bearings. Tapered roller bearings. Metric

series. Tolerances. Part li —Tolerance classes 6 and 5

Ref. Title R578 -1969 Tapered roller bearings. Tolerances. Inch series. Normal tolerances. 2d edition R579 -1967 Determination of total moisture in coke R580 -1967 Oven test for moulded fittings in unplasticized

polyvinyl chloride (PVC) for use under

pressure R581 -1967 Definition of weldability

R582 -1967 Rolling bearings. Tolerances. Metric series bearings. Chamfer dimension limits and maxi- mum shaft and housing fillet radius R583 -1967 Tolerances on the total thickness of conveyor

belts and on the thicknesses of covers R584 -1967 Plastics. Determination of the maximum temperature and the rate of increase of temperature

during the setting of unsaturated polyester

resins R585 -1967 Plastics. Determination of the moisture content

of non-plasticized cellulose acetate R586 -1967 Determination of ash of coke R587 -1967 Determination of chlorine in coal and coke using

Eschka mixture R588 (incorporated in R862-1968)

R589 -1967 Determination of total moisture in hard coal R590 -1967 Oil of Brasilian sassafras R591 -1967 Titanium dioxide for paints

R592 -1967 Determination of the optical rotation of essential

oils R593 -1967 Paper. Untrimmed stock sizes for the ISO-A

series (Supplementary series)

Erratum Erratum of first printing. May 1^67 R594 -1967 Conical fittings for syringes, needles and other medical equipment. Definition and dimensional characteristics for conical fittings with

a 6% and a 10% taper R595 -1967 Syringes for medical use R596 -1967 Hypodermic needles R597 -1967 Definitions and terminology of cements R598 -1967 Limitations of angles of slope and rotation for welding positions for straight manual arc welds made with covered electrodes of mild

steel and low alloy high tensile steels R599 -1967 Plastics. Determination of the percentage of

extractable materials in polyamides

R600 -1967 Plastics. Determination of the viscosity ratio of polyamides in concentrated solution R601 -1967 Determination of arsenic in coal and coke R602 -1967 Determination of mineral matter in coal R603 -1967 Bonded abrasive products. Grinding-wheel di- mensions (Part 1) Erratum Erratum of first printing. August 1967 R604 -1967 Determination of compressive properties of

plastics R605 -1967 Pulses. Methods of test R606 -1967 Short pitch transmission precision roller chains and chain wheels R607 -1967 Surface active agents in powder form. Preparation of a reduced sample

R608 -1967 Lengths of classical V-belts (Sections Z. A. B, C, D, E)
80 ENGINEERING STANDARDS I

TABLE 13. Numerical List — ISO Recommendations — Continued

Ref. Title Ref. R609 -1967 Determination of carbon and hydrogen in coal R637 -1967

and coke by the high temperature combustion

method

R610 -1967 High-tensile steel chains (round link) for chain conveyors and coal ploughs

R61 1 -1967 Braking of motor vehicles and their trailers. Terminology

R612 -1967 Dimensions of motor vehicles and their trailers. R638 -1967

Designations and definitions R613 -1967 Magnetic compasses, binnacles and azimuth R639 -1967

reading devices, class B, for use in sea navi- R640 -1967

gation

R614 -1967 Shipbuilding details. Testing of toughened glasses R641 -1968

for ships' side scuttles and fixed lights by the R642 -1967

punch method

R615 -1967 Methods for determining the mechanical prop- R643 -1967

erties of the weld metal deposited by elec- trodes 3.15 mm or more in diameter R644 -1967

R616 -1967 Determination of the shatter indices of coke R617 -1967 Calculation of rectangular symmetrical fillet welds statically loaded in such a way that the R645 -1967

transverse section is not under any normal

stress (o-= 0) R618 -1967 Paper. Overall trimmed sizes of articles of sta- R646 -1967

tionery that include detachable sheets R619 -1967 Methods of chemical analysis of manganese R647 -1968

ores. Determination of chromium content R620 -1967 Methods of chemical analysis of manganese

ores. Determination of zinc content. (Polar- R648 -1968

ographic method, for zinc content from 0.005 R649 -1968

to 0.1% inclusive) R650 -1968

R621 -1967 Methods of chemical analysis of manganese

ores. Determination of metallic iron content. R651

(Photometric method for metallic iron content R652

up to and including 2%)

R622 -1967 Determination of phosphorus in ash from coal R623 -1967 Paper and board. Sizes of folders and files R624 -1967 Cellulose pulps. Extraction from pulps of materials soluble in dichloromethane R625 -1967 Determination of carbon and hydrogen in coal and coke by the Liebig method

R626 -1967 Strength calculation of butt welded joints

R627 -1967 Fundamental welding positions and definitions of rotation and slope for straight welds R628 -1967 Common names for pesticides. Seventh list R629 -1967 Chemical analysis of steels. Determination of manganese (Spectrophotometric method) Erratum R630 -1967 Structural steels R657/III

R631 -1967 Mosaic parquet panels -1969

R632 -1967 Methods of test for determining whether an elec- trode is a deep penetration electrode R657/IV

R633 -1967 Cork. Glossary -1969

R634 -1967 Methods of test for general purpose electrical cables with copper conductors for aircraft R657/VII

R635 -1967 Code of symbols for covered electrodes for arc -1969

welding of mild steels and low alloy high tensile steels R657/IX

R636 -1967 Code of symbols for filler rods for gas welding -1969

of mild steels and low alloy high tensile steels

1968

1968 R653 -1968

R654 -1968

R655 -1968

R656 -1968

R657/I

-1968

Erratum R657/II

-1968

Title Methods of test for determining the mechanical

properties of weld metal deposited by filler rods for gas welding mild steels and low alloy high tensile steels with Annex: Information concerning heat treat- ment

Cellulose pulps. Determination of dry matter

content of pulp

Symbols for languages, countries and authorities Calibration of standardized blocks to be used for Vickers hardness testing machines

Interchangeable spherical ground glass joints

Hardenability test by end quenching steel (Jominy test) Micrographic determination of the austenitic grain size of steels Conventional signs to be used in schemes for the installations of ventilation systems in ships

Statistical vocabulary and symbols. First series of terms and symbols. Part 1: Statistical vocabulary

6 and 7 bit coded character sets for information processing interchange Determination of the yields of tar, water, gas and coke residue by low temperature distilla- tion of brown coal and lignite One-mark pipettes

Density hydrometers for general purposes

Relative density 60/60 °F hydrometers for general purposes

Solid-stem calorimeter thermometers

Enclosed-scale calorimeter thermometers Long solid-stem thermometers for precision use

Short solid-stem thermometers for precision use Long enclosed-scale thermometers for precision use Short enclosed-scale thermometers for precision use

Structural steel sections. Part 1. Dimensions and

sectional properties of hot-rolled equal-leg

angles — Metric series

Erratum of first printing April 1968 Structural steel sections. Part II. Dimensions

and sectional properties of hot-rolled unequalleg angles. Metric series

Erratum of first printing April 1 968 Structural steel sections. Part III. Dimensions

and sectional properties of hot-rolled equalleg angles — Inch series Structural steel sections. Part IV. Dimensions

and sectional properties of hot-rolled unequalleg angles — Inch series Dimensions of hot-rolled steel sections. Part VII. Parallel flange I-beams. Inch series. Dimensions and sectional properties

Structural steel sections. Part IX. Dimensions

and sectional properties of hot-rolled parallel flange column sections — Inch series

I
ISO RECOMMENDATIONS 81

TABLE 13. Numerical List — ISO Recommendations — Continued

Ref. Title R658 -1968 Oleaginous seeds. Determination of impurities

R659 -1968 Oleaginous seeds. Determination of oil content R660 -1968 Crude vegetable oils and fats. Determination of

acidity

R661 -1968 Crude vegetable oils and fats. Preparation of

contract sample for analysis

R662 -1968 Crude vegetable oils and fats. Determination of moisture and volatile matter R663 -1968 Crude vegetable oils and fats. Determination of

insoluble impurities

R664 -1968 Oleaginous seeds. Reduction of contract samples

to samples for analysis

R665 -1968 Oleaginous seeds. Determination of moisture and volatile matter R666 -1968 Mounting of plain grinding wheels by means of hub flanges

R667 -1968 Determination of rate of cure of rubber compounds by the shearing disk viscometer

Erratum Erratum of first printing February 1 968 R668 -1968 Dimensions and ratings of freight containers R669 - 1 968 Rating of resistance welding equipment

R670 -1968 Dimensions of straight resistance spot welding

electrodes R671 -1968 Chemical analysis of steel and cast iron. Deter- mination of sulphur (Method after combustion

in a current of oxygen and titration with sodium borate) R672 -1968 Analysis of soaps. Determination of moisture and volatile matter R673 -1968 Analysis of soaps. Determination of foreign matter of low solubility in ethanol R674 -1968 Calibration of standardized blocks to be used

for Rockwell B and C hardness scale testing machines

R675 -1968 Determination of dimensional change of woven

fabrics subjected to laundering near the boil- ing point. R676 -1968 Spices and condiments. Nomenclature. First list R677 -1968 Basic rack of straight bevel gears for general

engineering and heavy engineering

R678 -1968 Modules and diametral pitches of straight bevel

gears for general engineering and heavy

engineering

R679 - 1 968 Method of testing strength of cements R680 -1968 Chemical analysis of cements. Main constituents of Portland cement R681 -1968 Chemical analysis of cements. Minor constit- uents of Portland cement R682 -1968 Chemical analysis of cements. Determination

of sulphur as sulphide

R683/I Heat-treated steels, alloy steels and free cutting -1968 steels. Part I: Quenched and tempered un- alloyed steels R683/II Heat-treated steels, alloy steels and free cutting

-1968 steels. Part 2: Wrought, quenched and tem- pered steels with 1% chromium and 0.2%

molybdenum

R684 -1968 Analysis of soaps. Determination of total free

alkali R685 -1968 Analysis of soaps. Determination of total alkali

Ref. R686 -1968

R687 -1968

R688 -1968

R689 -1968

R690 -

R691 -

R692 - R693 - R694 - Erratum R695 -

R696

R697 -

-1968

-1968

-1968 -1968

-1968

-1968

-1968

-1968

R698 -1968

R699 -1968

R700 -1968

R701 -1968

R702 -1968

R703 -1968

R704 -1968

R705 -1968

R706 -1968

R707 -1968

R707 -Add.

-1969

R708 -1968

R709 -1968

R710/I

-1968

R710/n

-1968

R711 -1968

R712 -1968

R713 -1968

R714 -1968

Title 35 mm Filmstrips. Dimensions and formats Determination of moisture in the analysis sample

of coke

Filler rods for braze welding. Methods of test for determining the characteristics of the deposited metal Microcopies. Legibility tests. Description and

use of the ISO micromire (ISO micro test object) for checking a reading apparatus

Bibliographical references. Essential and sup- plementary elements Tolerances on spanner gaps and sockets (Metric

values for general use)

Pulps. Determination of alkali solubility of pulp

Dimensions of seam welding wheel blanks

Positioning of magnetic compasses in ships

Erratum of first printing March 1968 Determination of the resistance of glass to attack by a boiling aqueous solution of mixed alkali Surface active agents. Measurement of foaming power

Surface active agents. Determination of apparent

density of washing powders before and after compaction

Filler rods for braze welding. Methods of test for determining the conventional bond strength on

steel, cast iron and other metals

Pulps. Determination of alkali resistance Rating of manual arc welding equipment

International gear notation. Symbols for geometrical data Spindle noses and face plates types A and Camlock. Sizes for interchangeability

Troughability of conveyor belts. (Characteristic and method of test) Naming principles

Method for the determination of density of latex Determination of coagulum content of latex Milk and milk products. Sampling

Addendum to ISO/R 707-1968

Filler rods for gas welding. Test to determine the

compatibility of steel filler rods and the parent metal in the welding of steels Determination of ester value and calculation of

ester content of essential oils Graphical symbols for use on detailed maps,

plans and geological cross sections. Part I: General rules of representation

Graphical symbols for use on detailed maps,

plans and geological cross sections. Part II: Representation of sedimentary rocks Cereals and cereal products. Determination of moisture content (Basic reference method)

Cereals and cereal products. Determination of moisture content (Routine method)

Chemical analysis of zinc. Polarographic deter- mination of lead and cadmium

Chemical analysis of zinc. Photometric determination of iron

1
82 ENGINEERING STANDARDS

TABLE 13. Numerical List — ISO Recommendations — Continued

Rcf. R715 -1968

R716 -1968

R717 -1968 R718 -1968

R719 -1968

R720 -1968

R721 -1968

R722 -1968

R723 -1968

R724 -1968

R725 -1968

R726 -1968

R727 -1968

R728 -1968

R729 -1968

R730 -1968

R731 -1968

R732 -1968

R733 -1968

R734 -1968

R735 -1968

R736 -1968

R737 -1968

R738 -1968

R739 -1968

R740 -1968

R74

I yyyct

R742 -1968

R743 -1968

R744 -1968

Tille Chemical analysis of zinc. Polarographic deter- mination of lead Verification of Rockwell B and C scale hardness

testing machines

Rating of sound insulation for dwellings

Methods for thermal shock tests on laboratory

glassware Determination of the hydrolytic resistance of

glass grains at 98 °C

Determination of the hydrolytic resistance of

glass grains at 121 °C Rock drilling. Integral stems Rock drilling. Hollow hexagonal drill steels in bar form Rock drilling. Forged collared shanks and chuck

bushings for hollow hexagonal drill steels ISO general purpose metric screw threads. Basic dimensions ISO inch screw threads. Basic dimensions

Calibration of standardized blocks to be used for

Brinell hardness testing machines

Socket fittings for pipes under pressure. Unplasticized polyvinyl chloride (PVC) fittings with plain sockets. Metric series Size analysis of coke

Oleaginous seeds. Determination of acidity of

oils Three-point linkage of agricultural wheeled trac- tors for attachment of mounted implements

Formic acid for industrial use. Methods of test Dimensions for 127, 120 and 620 roll film, backing paper and film spools

Hexagon bolts and nuts. Metric series. Toler- ances on widths across flats. Widths across corners Oilseed residues. Determination of oil content Oilseed residues. Determination of ash insoluble

in hydrochloric acid Oilseed residues. Determination of diethyl ether

extract Coniferous sawn timber. Sizes— Methods of measurement

Coniferous sawn timber. Sizes — Tolerances and

shrinkage

Sodium carbonate for industrial use. Preparation and storage of test samples

Sodium carbonate for industrial use. Determination of total soluble alkalinity. Volumetric method

Sodium carbonate for industrial use. Determination of sodium hydrogen carbonate. Volumetric method

Sodium carbonate for industrial use. Deter- mination of chloride content. Volhard volu- metric method

Sodium carbonate for industrial use. Deter- mination of sulphate content. Barium sul- phate gravimetric method

Sodium carbonate for industrial use. Deter- mination of iron content. 2.2'-bipyridyl

photometric method

Rcf. rule

R7'45 -1968 Sodium carbonate for industrial use. Deter- mination of loss of mass and of nonvolatile matter at 250 °C R746 -1968 Sodium carbonate for industrial use. Deter- mination of matter insoluble in water at 50 °C R747 -1968 Sodium carbonate for industrial use. Expression

of test results R748 -1968 Liquid flow measurement in open channels by

velocity area methods R749 -1968 Oilseed residues. Determination of total ash R750 -1968 Fruit and vegetable products. Determination of

titratable acidity R751 -1968 Fruit and vegetable products. Determination of

water-insoluble solids R752 -1968 Zinc ingots

R753 -1968 Methods of test for acetic acid R754 -1968 Methods of test for acetic anhydride

R755 -1968 Methods of test forn-butanol .

, R756 -1968 Methods of test for isopropyl alcohol R757 -1968 Methods of test for acetone R758 -1968 Method for the determination of density of

liquids at 20 °C R759 -1968 Method for the determination of residue on

evaporation on a water bath R760 -1968 Determination of water by the Karl Fischer method

R761 -1968 Method for the determination of bromine index R762 -1968 Fruit and vegetable products. Determination of mineral impurities

R763 -1968 Fruit and vegetable products. Determination of ash insoluble in hydrochloric acid R764 -1968 "Antimagnetic" watches for general purpose use R765 -1968 Pesticides considered not to require common

names. First list R766 -1968 Fibre building boards. Determination of dimensions of test pieces

R767 -1968 Fibre building boards. Determination of moisture

content R768 -1968 Fibre building boards. Determination of bending

strength

R769 -1968 Fibre building boards. Determination of water

absorption and of swelling in thickness after immersion in water R770 -1968 Oil of eucalyptus globulus R771 -1968 Oilseed residues. Determination of moisture and

volatile matter R772 -1968 Vocabulary of terms and symbols used in connection with the measurement of liquid flow

with a free surface R773 -1969 Rectangular or square parallel keys and their corresponding keyways (Dimensions in milli- metres) R774 -1969 Taper keys with or without gib head and their corresponding keyways (Dimensions in milli- metres) R775 -1969 Cylindrical and 1/10 conical shaft ends R776 -1968 Pulps. Determination of acid insoluble ash R777 -1968 Pulps. Determination of calcium content R778 -1968 Pulps. Determination of copper R779 -1968 Pulps. Determination of iron
ISO RECOMMENDATIONS 83

TABLE 13. Numerical List — ISO Recommendations — Continued

Ref. R780 -1968

R781 -1968

R782 -1968

R783 -1968

R784 -1968

R785 -1968

R786 -1968

R787 -1968

R788 -1968

R789 -1968

R790 -1968

R791 -1968

R792 -1968

R793 -1968

R794 -1968

R795 -1968

R796 -1968

R797 -1968

R798 -1968

R799

R800

R801

R802

-1968 -1968

-1968

-1968

R811

R812

R813

-1968

-1968

-1968

R803 -1968

Title Ref.

Pictorial markings for handling of goods (general R804 -1968

symbols) Measurement of fluid flow by means of Venturi

tubes R805 -1968

Microcopy. Measurement of the screen luminance of microfilm readers Mechanical testing of steel at elevated tempera- R806 -1968

tures. Determination of lower yield stress and

proof stress and proving test Conventional signs to be used in schemes for the R807 -1968

installations of sanitary systems in ships

Common names for pesticides. Eighth list Units and symbols for refrigeration R808 -1968

General methods of test for pigments

Ultramarine pigments

Test code for agricultural tractors R809 -1968

Marking of freight containers. Series 1 and 2 Chemical analysis of magnesium and its alloys. Gravimetric determination of aluminium in magnesium alloys (aluminium content between R810 -1968

1.5 and 12.0%)

Chemical analysis of magnesium and its alloys. Photometric determination of iron (Orthophenanthroline method applicable to iron content between 0.002 and 0.05%)

Chemical analysis of aluminium and its alloys. Photometric determination of iron (Orthophenanthroline method applicable to iron content between 0.05 and 2.50%)

Chemical analysis of magnesium and its alloys. Photometric determination of copper (Oxalyldihydrazide method applicable to copper

content between 0.002 and 0.4%)

Chemical analysis of aluminium and its alloys. Photometric determination of copper (Oxalyldihydrazide method applicable to copper content between 0.002 and 0.8%)

Chemical analysis of aluminium and its alloys. Electrolytic determination of copper in alu- minium alloys (Copper content greater than or R8 1 7 - 1 968

equal to 0.50%) r818 .jg^g

Chemical analysis of aluminium and its alloys. R819 -1968

Gravimetric determination of silicon (Silicon R820 -1968

content greater than or equal to 0.30%) R821 -1968

Chemical analysis of aluminium and its alloys. Gravimetric determination of zinc in alumin- R822 -1968

ium alloys (Zinc^content between 0.50 and R823 -1968

6.5%)

Pilot ladders R824 -1968

Plastics. Basis for specification for phenolic

moulding materials R825 -1968

Pulps. Determination of saleable mass, in lots, of pulp baled in sheet form Aluminium oxide primarily used for the produc- R826 -1968

tion of aluminium. Preparation and storage of

test samples R827 -1968 Aluminium oxide primarily used for the production of aluminium. Determination of loss of R828 -1968

mass at 300 °C (conventional moisture)

R814 -1968

R815 -1968

R816 -1968

Title Aluminium oxide primarily used for the production of aluminium. Preparation of sample solution for analysis

Aluminium oxide primarily used for the production of aluminium. Determination of iron content — 1,1 0-phenanthroline photometric method

Aluminium oxide primarily used for the production of aluminium. Determination of loss of mass at 1000 °C and 1200 "C Chemical analysis of magnesium and magnesium

alloys. Polarographic determination of zinc (Zinc content between 0.1 and 4%)

Chemical analysis of aluminium and aluminium

alloys. Photometric determination of silicon (Silicon content between 0.02 and 0.4%)

Chemical analysis of magnesium and magnesium

alloys. Photometric determination of manganese. Periodate method (Manganese content between 0.01 and 0.8%)

Chemical analysis of magnesium and magnesium

alloys. Photometric determination of manganese. Periodate method (Manganese content

less than 0.01%)

Method of test for resistance of fabrics to penetration by water (Hydrostatic head test) Method of test for temperature limit of brittle- ness for vulcanized rubbers

Preparation of test piece and method of test of

the adhesion of vulcanized rubber to metal where the rubber is assembled to one metal

plate Preparation of test piece and method of test of

the adhesion of vulcanized rubber to metal where the rubber is assembled to two metal

plates Method of test for the compression set under

constant deflection at normal and high temperatures of vulcanized rubbers Determination of tear strength of small test pieces of vulcanized rubbers (Delft test piece)

Number designation of organic refrigerants Fibre building boards. Definition. Classification Fibre building boards. Determination of density

Particle boards. Definition. Classification

Particle boards. Determination of dimensions of

test pieces

Particle boards. Determination of density

Particle boards. Determination of moisture

content Household refrigerators. Part I — Performance

requirements

Household refrigerators. Part II — Special low- temperature compartments for the storage of

frozen foodstuffs Mechanical property limits for rolled products of aluminium and aluminium alloys Mechanical property limits for extruded products

of aluminium and aluminium alloys Mechanical property limits for rivet stock of aluminium and aluminium alloys
84 ENGINEERING STANDARDS

TABLE 13. Numerical List — ISO Recommendations — Continued

Ref. R829

R830

R831

R832

Title Ref. -1968 Mechanical property limits for aluminium alloy R863 -1968

forgings R864 -1968

-1968 Terminology relating to freight containers -1968 Rules for construction of stationary boilers -1968 Abbreviations of typical words in bibliographical R865 -1968

references R833 -1968 Abbreviations of generic names in titles of R866 -1968

periodicals

R834 -1968 Fire resistance tests of structures R867 -1968

R835 -1968 Graduated pipettes (excluding blowout pipettes) R836 -1968 Vocabulary for the refractories industry Erratum f R837 -1968 Aircraft seat rails and pins R868 -1968

R838 -1968 Paper. Holes for general filing purposes R839 -1968 Milling machine arbors with 7/24 tapers and

milling machine accessories R869 -1968

R840 -1968 Code for numerical control of machines (compatible with the ISO 7 bit character set) R870 - 1 968 R841 -1968 Axis and motion nomenclature for numerically

controlled machines R871 -1968

R842 -1968 Sampling raw materials for paints and varnishes R843 -1968 International system for the transliteration of R872 -1968

Greek characters into Latin characters R844 -1968 Plastics -Compression test of rigid cellular R873 -1968

plastics R874 -1968

R845 -1968 Plastics- Determination of apparent density of R875 -1968

cellular plastics R846 -1968 Plastics- Recommended practice for the evalu- R876 -1968

ation of the resistance of plastics to fungi by

visual examination R847 -1968 Phosphoric acid for industrial use— Determina- R877 -1968

tion of sulphate content — Volumetric method

R848 -1968 Phosphoric acid for industrial use — Determina- R878 -1968

tion of calcium content— Volumetric method

R849 -1968 Phosphoric acid for industrial use— Determination of iron content — 2, 2'-bipyridyl spectro- R879 -1968

photometric method

R850 -1968 Sodium tripolyphosphate for industrial use —

Determination of matter insoluble in water R880 -1968

R851 -1968 Sodium tripolyphosphate for industrial use —

Measurement of pH potentiometric method R881 -1968

R852 -1968 Sodium tripolyphosphate and sodium pyro- R882 -1968

phosphate for industrial use— Determination R883 -1969

of iron content— 2,2' -bipyridyl spectrophotometric method R884 -1968

R853 -1968 Sodium tripolyphosphate and sodium pyro- phosphate for industrial use— Determination

of loss on ignition K%%5 -1968

R854 -1968 Requirements for 28-volt d.c. flat strip fuses for

aircraft r886 _i968

R855 -1968 Oil of lemon, obtained by expression, Italy R856 -1968 Oil of peppermint. United Kingdom, U.S.A., France and Italy R857 -1968 Definitions of welding processes R887 -1968

R858 -1968 Netting yarns for fishing nets. Designation in the Tex system R888 -1968

R859 -1968 Testing and rating room air conditioners R860 -1968 International unification of concepts and terms R889 -1968

R86] -1968 Hexagon socket head cap screws. Metric series R862 -1968 Surface active agents. Glossary R890 -1968

R862/Add. 1 ISO/R 862 -Addendum 1 -Surface active -1969 agents — Vocabulary

Title Pozzolanicity test for pozzolanic cements

Solid wires for gas-shielded metal-arc welding

of mild steel. Dimensions of wires, spools, rims and coils Dimensions and pitching of slots on platens for projection welding machines

Centre drills for centre holes without protecting chamfers — Type A

Spindle noses and face plates. Bayonet type. Sizes for interchangeability. Metric series

Plastics. Determination of indentation hardness

of plastics by means of a durometer (Shore

hardness)

Plastics. Preparation of specimens for optical

tests on plastics materials. Moulding method

Plastics. Preparation of specimens for optical

tests on plastics materials. Casting method

Plastics. Determination of the temperature of evolution of flammable gases from plastics

Plastics. Determination of ash of unplasticized

cellulose acetate Peaches. Guide to cold storage Fresh fruits and vegetables. Sampling

Determination of solubility of essential oils in ethanol

Special method of mechanical testing to deter- mine the coding for deep penetration elec- trodes

Plastics. Determination of resistance of plastics to colour change upon exposure to daylight

Plastics. Determination of resistance of plastics

to colour change upon exposure to light of the enclosed carbon arc

Plastics. Determination of resistance of plastics to colour change upon exposure to light of a xenon lamp

Asbestos-cement pipes, joints and fittings for sewerage and drainage Asbestos-cement siding shingles

Specification for cardamoms

Throwaway carbide indexable inserts. Dimensions

Pictorial marking of transit packages containing

photographic materials sensitive to radiant energy

Bolts and screws. Radii under the head for general purpose bolts and screws. Metric series Chemical analysis of aluminium and aluminium

alloys. Photometric determination of manganese (Manganese contents between 0.005 and

1.5%)

Washers for hexagon bolts and nuts. Metric

series Nominal lengths for bolts, screws and studs. Thread lengths for general purpose bolts Test code for stationary steam generators of the power station type Location and width of the recording head for centre sound records on 16 mm perforated

magnetic film
ISO RECOMMENDATIONS g5

TABLE 13. Numerical List — ISO Recommendations — Continued

Ref. Title Ref. R891 -1968 Location and width of the recording head for edge sound records on 16 mm perforated

magnetic film

R9I4 -1968

R892 -1968 Dimensions of projection reels for 8 mm motionpicture film R915 -1968

R893 -1968 Surface active agents. Technical sodium alkyl- sulphonates. Methods of analysis R916 -1968

R894 -1968 Surface active agents. Technical sodium pri- R917 -1968 mary alkylsulphates. Methods of analysis R918 -1969

R895 -1968 Surface active agents. Technical sodium sec- ondary alkylsulphates. Methods of analysis R9I9 -1969

R896 -1968 Surface active agents. Scientific classification R897 -1968 Identification of the emulsion side of edgemarked roll film for still picture cameras R920 -1969

R898/I Mechanical properties of fasteners. Part 1. Bolts, R920/A1

-1968 screws and studs -1969

R898/II Mechanical properties of fasteners. Part II. Nuts R921 -1969

-1969 with specified proof load values R922 -1969

R898/III Mechanical properties of fasteners. Part III. -1969 Marking of bolts, screws, studs and nuts R923 -1969

R899 -1968 Determination of tensile creep of plastics R900 -1968 Aluminium oxide primarily used for the production of aluminium. Determination of titanium R924 -1969

content. Tiron photometric method R925 -1969

R901 -1968 Aluminium oxide primarily used for the production of aluminium. Determination of absolute R926 -1969

density. Pyknometer method

R902 -1968 Aluminium oxide primarily used for the production of aluminium. Measurement of the angle

R927 -1969

of repose R928 -1969

R903 -1968 Aluminium oxide primarily used for the production of aluminium. Measurement of untamped R929 -1969

density

R904 -1968 Hydrochloric acid for industrial use. Determination of total acidity. Volumetric method

R930 -1969

R905 -1968 Hydrochloric acid for industrial use. Evaluation R931 -1969

of hydrochloric acid concentration by measure- R932 -1969

ment of density

R906 -1968 Hydrochloric acid for industrial use. Determination of sulphate content. Barium sulphate

R933 -1969

gravimetric method R934 -1969

R907 -1968 Hydrochloric acid for industrial use. Determination of sulphated ash. Gravimetric method R935 -1969

R908 -1968 Hydrochloric acid for industrial use. Determination of oxidizing or reducing substances. R936 -1969

Volumetric method R937 -1969

R909 -1968 Hydrochloric acid for industrial use. Determination of iron content. 2,2'-bipyridyl spectro- R938 -1969

photometric method

j R910 -1968 Sulphuric acid and oleum for industrial use. Determination of total acidity and calculation of R939 -1969

free SO3 content of oleum. Volumetric method R940 -1969

1 R911 -1968 Sulphuric acid for industrial use. Evaluation of

sulphuric acid concentration by measure- R941 -1969

ment of density

R912 -1968 Sulphuric acid and oleum for industrial use. De- R942 -1969

termination of sulphur dioxide content. Barium R943 -1969

sulphate gravimetric method R944 -1969

R913 -1968 Sulphuric acid and oleum for industrial use. Determination of residue on ignition. Gravimetric R945 -1969

method R946 -1969

Title Sulphuric acid and oleum for industrial use. Determination of total nitrogen content. Volumetric method

Sulphuric acid and oleum for industrial use. Determination of iron content. 2,2'-bipyridyl

spectrophotometric method

Testing of refrigerating systems

Testing of refrigerant compressors

Test method for distillation (distillation yield and

distillation range)

Guide for the preparation of classified vocabularies (Example of method)

Method of test for wool fibre length barbe and

hauler using a comb sorter Amendment to ISO/R 920-1969

Nuclear energy glossary. First series of terms

Plastics. Determination of soluble matter of

crystalline polypropylene by boiling n-heptane

Expression and presentation of results of coal cleaning tests Principles and conventions for flowsheets for coal preparation plant Determination of carbon dioxide in coal by the gravimetric method

Determination of nitrogen, total sulphur, chlorine and phosphorus in coke

Spices and condiments. Determination of ex- traneous matter

Spices and condiments. Determination of total ash

Spices and condiments. Determination of waterinsoluble ash

Spices and condiments. Determination of acid- insoluble ash Green bananas. Guide to storage and transport Animal fats. Determination of insoluble impurities

Animal fats. Determination of moisture and

volatile matter Animal fats. Determination of water (entrain- ment distillation method)

Animal fats. Determination of solidification point of fatty acids (titre) Meat and meat products. Determination of ash Meat and meat products. Determination of nitro- gen content Hand-operated stillage trucks. Principal dimensions Spices and condiments. Determination of moisture content (entrainment method)

Spices and condiments. Determination of

alcohol-soluble extract Spices and condiments. Determination of cold water soluble extract Whiteheart malleable cast iron Blackheart malleable cast iron

Pearlitic malleable cast iron Designation of the microstructure of graphite

in cast iron Beam unnotched impact test for grey cast iron

li
86 ENGINEERING STANDARDS

TABLE 13. Numerical List — ISO Recommendations — Continued

Ref. Title Ref. R947 -1969 Recommended practice for radiographic inspec- R978 -1969

tion of fusion welded butt joints in steel pipes up to 50 mm (2 in) wall thickness R979 -1969

R948 -1969 Spices and condiments. Sampling

R949 -1969 Cauliflowers. Guide to cold storage R980 -1969

R950 -1969 Cereals. Sampling (as grain) R951 -1969 Pulses. Sampling

R952 -1969 Tensile testing of light metal and light metal

alloy tubes R981 -1969

R953 -1969 Drift expanding test on light metal and light metal alloy tubes R954 -1969 Simple bend test for light metal and light metal R982 -1969

alloy sheet and strip of thickness between 0.2 mm (0.008 in) and 7 mm (0.25 in) R955 -1969 Flattening test on aluminum and aluminum R983 -1969

alloy tubes R956 -1969 Tensile test for light metal and light metal alloy wires R984 -1969

R957 -1969 Simple torsion test for aluminum and aluminum

alloy wire R958 -1969 Wrapping test for aluminum and aluminum alloy R985 -1969

wire R959 -1969 Spices and condiments. Black pepper and white

pepper, whole and ground. Specification

R960 -1969 Plastics. Determination of the water content in R986 -1969

polyamides

R961 -1969 Implementation of the 6 and 7-bit coded character sets on 7 track 12.7 mm (1/2 in) magnetic R987 -1969

tape R962 -1969 Implementation of the 7-bit coded character set R988 -1969

on 9 track 12.7 mm (1/2 in) magnetic tape R963 -1969 Guide for the definition of 4-bit character sets R989 -1969

derived from the ISO 7-bit coded character

set for information processing interchange R990 -1969

R964 -1969 Shipbuilding details. Mating dimensions for pipeline flanges for ships R991 -1969

R965/I ISO general purpose metric screw threads. -1969 Tolerances. Part 1. Principles and basic data R965/II ISO general purpose metric screw threads. -1969 Tolerances. Part 2. Limits of sizes for com- R992 -1969

mercial bolt and nut threads. Medium quality

R965/I1I ISO general purpose metric screw threads. -1969 Tolerances. Part 3. Deviations for construe- R993 -1969

tional threads R966 -1969 Seeds. Sampling and methods of test R967 -1969 Common names for pesticides. Ninth list R994 -1969

R968 -1969 Common names for pesticides. Tenth list R969 -1969 Common names for pesticides. Eleventh list R970 -1969 Common names for pesticides. Twelfth list R995 -1969

R971 -1969 Common names for pesticides. Thirteenth list R972 -1969 Spices and condiments. Chillies, whole and

ground. Specification R996 -1969

R973 -1969 Spices and condiments. Pimento (Allspice) whole and ground. Specification

R974 -1969 Plastics. Method of determining the brittleness temperature by impact R997 -1969

R975 -1969 Determination of the yield of benzenesolubie

extract in brown coals and lignites R976 - 1 969 Method for the determination of pH of latex R998 - 1 969 R977 -1969 Sodium hydroxide for industrial use. Preparation and storage of test sample R999 - 1 969

Title Sodium hydroxide for industrial use. Preparation of sample solution Sodium hydroxide for industrial use. Determination of alkalinity. Volumetric method

Sodium hydroxide for industrial use. Determination of the carbon dioxide content, ex- pressed as sodium carbonate. Gas — volu- metric method

Sodium hydroxide for industrial use. Determination of chloride content. Volhard volumetric method

Sodium hydroxide for industrial use. Determination of sulphate content. Barium sulphate

gravimetric method

Sodium hydroxide for industrial use. Determination of iron content. 2,2'-bipyridyl spectro- photometric method

Sodium hydroxide for industrial use. Determination of silica content. Gravimetric method

by insolubilization Sodium hydroxide for industrial use. Determination of silica content. Gravimetric method

by precipitation of the quinolinesilicomolybdic complex

Sodium hydroxide for industrial use. Determination of calcium. EDTA complexometric

method

Sodium hydroxide for industrial use. Determination of water-insoluble matter Potassium hydroxide for industrial use. Preparation and storage of test sample

Potassium hydroxide for industrial use. Preparation of sample solution Potassium hydroxide for industrial use. Determination of alkalinity. Volumetric method

Potassium hydroxide for industrial use. Determination of the carbon dioxide content, ex- pressed as potassium carbonate. Gas — volu- metric method

Potassium hydroxide for industrial use. Determination of chloride content. Volhard volu- metric method

Potassium hydroxide for industrial use. Determination of sulphate content. Barium sulphate

gravimetric method

Potassium hydroxide for industrial use. Determination of iron content. 2,2'-bipyridyl spectro- photometric method

Potassium hydroxide for industrial use. Determination of silica content. Gravimetric method

by insolubilization Potassium hydroxide for industrial use. Determination of silica content. Gravimetric method

by precipitation of the quinolinesilicomolybdic complex

Potassium hydroxide for industrial use. Determination of calcium. EDTA complexometric

method

Potassium hydroxide for industrial use. Determination of water-insoluble matter Index of a publication
ISO RECOMMENDATIONS 87

TABLE 13. Numerical List— ISO Recommendations — Continued

Ref. Title RlOOO-1969 Rules for the use of units of the international sys- tem of units and a selection of the decimal multiples and sub-multiples of the SI units RlOOl-1969 Magnetic tape labelling and file structure for in- formation interchange

R1002/I Rolling bearings. Airframe bearings. Part I: In- -1969 troduction. General, Boundary dimensions.

Tolerances, Permissible load R1003-1969 Spices and condiments. Ginger, whole, in pieces and ground. Specification

R 1004- 1969 Print specifications for magnetic ink character

recognition

R1005/I Railway rolling stock material — Part 1 —Tyres

-1969 for trailer stock R1005/II Railway rolling stock material — Part 2 — Rough

-1969 tyres for trailer stock: Dimensions and

tolerances R1005/III Railway rolling stock material- Part 3 -Axles

-1969 for trailer stock R1005/IV Railway rolling stock material - Part 4- Rolled -1969 or forged wheel centres for tyred wheels for

trailer stock R1005/V Railway rolling stock material - Part 5 -Cast

-1969 wheel centres in non-alloy steel for tyred wheels for trailer stock R1005/VI Railway rolling stock material. Part 6. Solid - 1 969 wheels for trailer stock R1005/VII Railway rolling stock material. Part 7. Wheel

-1969 sets for trailer stock Rl 006- 1969 Modular co-ordination. Basic module

R1007-1969 Dimensions for 35 mm film magazines for still picture use and test for film pullout force Rl 008- 1969 Photographic black-and-white papers for general use. Preferred sizes of sheet material R1009-1969 Photographic black-and-white paper for roll paper printers. Preferred sizes of rolls RIO 10- 1969 Photographic colour paper for general use. Preferred sizes of sheet material RlOl 1-1969 Photographic colour paperfor roll paper printers. Preferred sizes of rolls R1012-1969 Photographic colour film for general use. Pre- ferred sizes of sheet material RlOl 3- 1969 Determination of the bulk density of coke in a

large container R1014-1969 Determination of the true relative density, the apparent relative density and the porosity of coke RIO 15- 1969 Determinafion of moisture in brown coals and

lignites by the direct volumetric method

R1016-1969 Determination of ash of brown coals and lignites R1017-1969 Benzene extract from brown coals and lignites- Determination of acetone-soluble material ("Resinous substances")

RlOl 8- 1969 Determination of the moisture-holding capacity

of hard coals RIO 19-1 969 Cinematography. Dimensions of daylight load- ing spools for 16 mm motion-picture film R 1020- 1969 Cinematography. Dimensions of daylight load- ing spools for double-8 mm motion-picture

film

Ref. Title R 102 1-1 969 Aircraft engine nacelle fire-extinguisher doors R 1022- 1969 Gaseous oxygen replenishment couplings for

aircraft R 1023- 1969 High pressure air charging valves for aircraft R 1024- 1969 Rockwell superficial hardness test (N and T

scales) for steel R 1025- 1969 Sectional beams for warp knitting machines. Terminology and dimensions R 1026- 1969 Fruit and vegetable products. Determination of

total solids R 1027- 1969 Radiographic image quality indicators. Principles and identification R 1028- 1969 Flowchart symbols for information processing

R 1029- 1969 Coniferous sawn timber defects; Classification R 1030- 1969 Coniferous sawn timber defects: Measurement R103 1-1969 Coniferous sawn timber defects; Terms and

definitions R 1032- 1969 Coniferous sawn timber sizes; Terms and

definitions R 103 3- 1969 Dimensions for general purpose push-pull

three-pole circuit-breakers for aircraft R 1034- 1969 Aircraft connections for ground air-conditioning

R 1035/1 Dimensions of hot-rolled steel bars. Part I. - 1 969 Round bars. Metric series

Erratum Erratum of first printing March 1969 R1035/II Dimensions of hot-rolled steel bars. Part 2. - 1 969 Square bars. Metric series R1035/III Dimensions of hot-rolled steel bars. Part 3. -1969 Flat bars. Metric series

Erratum Erratum of first printing March 1969 R 1036- 1969 Dyeing and finishing machines. Definition of

left and right sides R 1037- 1969 Beams for dyeing fibres and yarn R 1038- 1969 Rolling bearings. Cylindrical roller bearings. Radial internal clearance R 1039- 1969 Dimensions of cores for motion-picture and

magnetic films R 1040/1 Modular co-ordination. Horizontal multi- -1969 modules. 1 St part R 1041-1969 Determination of freezing point of essential oils R 1 042- 1 969 One-mark volumetric fiasks R 1043- 1969 Abbreviations (symbols) for plastics R 1044- 1969 Industrial trucks. Voltages of traction batteries

for electric trucks R 1045- 1969 Dimensions of straight resistance spot welding

electrodes (for loads greater than 1500 kgf) R 1046- 1969 Architectural and building drawings. Definitions and nomenclature R 1047- 1969 Architectural and building drawings. Presentation of drawings. Scales R 1 048- 1 969 Identification of exposed colour roll film R 1049- 1969 Continuous mechanical handling equipment for loose bulk materials. Vibrating conveyors and

feeders with rectangular or trapezoidal trough

R 1050- 1969 Continuous mechanical handling equipment

for loose bulk materials. Screw conveyors R105 1-1969 Rivet shank diameters (Diameter range 1 to 36 mm)

R 1 05 2- 1 969 Steels for general engineering purposes R 105 3- 1969 Chemical analysis of zinc. Photometric deter- mination of copper
88 ENGINEERING STANDARDS

TABLE 13. Numerical List— ISO Recommendations — Continued

Ref. Title R 1054- 1969 Chemical analysis of zinc. Polarographic deter- mination of cadmium in zinc R1055-1969 Chemical analysis of zinc and zinc alloys. Photometric determination of iron R 1056- 1969 Punched tape block formats for the numerical

control of machines. Coding of preparatory

functions G and miscellaneous functions M

R1057-1969 Interchangeable punched tape variable block format positioning and straight-cut numerically controlled machines

R 1058- 1969 Punched tape variable block format for posi- tioning and straight-cut numerically controlled machines

R 1059- 1969 Punched tape fixed block format for positioning and straight-cut numerically controlled machines

R 1060- 1969 Plastics. Designation of polyvinyl chloride resins Rl 06 1-1969 Plastics. Determination of free acidity of unplasticized cellulose acetate R 1 062- 1969 Common names for pesticides. Fourteenth list R 1063- 1969 Surface active agents. Determination of stability

in hard water R 1 064- 1 969 Surface active agents. Determination of apparent

density of pastes on filing R 1 065- 1969 Surface active agents. Determination of the cloud

point temperature (cloud point) of non-ionic

surface active agents obtained from ethylene oxide R 1 066- 1 969 Analysis of soaps. Determination of glycerol

R 1067- 1969 Analysis of soaps. Determination of unsaponifiable and unsaponified matter R 1068- 1969 Plastics. PVC resins. Determination of the compacted apparent bulk density

R 1069- 1969 Magnetic compasses and binnacles for sea navigation. Vocabulary

R 1070- 1969 Liquid flow measurement in open channels by

slope area method

R 107 1-1969 Code of symbols for covered electrodes for manual metal-arc welding of cast iron R 1072- 1969 General manufacturing characteristics of solid wood parquet strips with rectangular face R 1073- 1969 Alphanumeric character sets for optical recognition R 1074- 1969 Stability of counterbalanced lift trucks -Basic

tests R 1075- 1969 Performance requirements for heat-resisting

(190 °C) electrical cables with copper conductors for aircraft R1076-1969 General purpose electrical cables with alumin- ium or aluminium alloy conductors for aircraft R 1077- 1969 Dimensions of elastomeric toroidal sealing rings for pipe-fittings in aircraft (inch series — Class 1 tolerances) R 1078- 1969 Dimensions of elastomeric toroidal sealing rings

for aircraft (inch series — Class 1 tolerances) R 1079- 1969 Verification of Rockwell superficial N and T

scale hardness testing machines

R 1080- 1969 Cotter slots with 5% taper keys for boring machine tapers

Ref. Title R 1081-1969 Terms and definitions relating to drives using

V-belts and grooved pulleys

R 1082- 1 969 Shackle type connector units for high tensile

steel chain for conveyors R 1 083- 1 969 Spheroidal graphite or nodular graphite cast iron R1084-1969 Industrial tractors— Definition and nominal

rating

R 1085- 1969 Combinations of double ended wrench gaps R 1086- 1969 Title-leaves of a book

R 1087- 1969 Vocabulary of terminology

R 1088- 1969 Collection of data for determination of errors in. measurement of liquid flow by velocity area methods

R 1089- 1969 Dimensions of tubular electrode holders for spot welding machines

R 1090- 1969 Function ke>' syrnbols on typewriters R 109 1-1 969 Layout of printing and function keys on typewriters R 1092- 1969 Numeric section of ten-key keyboards for adding machines and calculating machines

Erratum Erratum of first printing June 1969 R 1 093-1 969 Keytop and printed or displayed symbols for adding machines and calculating machines

R 1 094- 1 969 Classification of adding machines and calculating

machines

R 1095- 1969 Shipbuilding details — Toughened glasses for

ships" side scuttles and fixed lights R 1096- 1969 Plywood -Classification R 1 097- 1 969 Plywood — Measurement of dimensions of panels

R1098-1969 Plywood- Veneer plywood for general useGeneral requirements

R 1 099- 1 969 Axial load fatigue testing Rl 100-1969 Liquid flow measurement in open channelsEstablishment and operation of a gauging sta- tion and determination of the stage-discharge

relation R 1 1 0 1 - 1 969 Tolerances of form and of position — Part I ; Generalities, symbols, indications on drawings Rl 102-1969 Mechanical connections between prime movers

and trailers — Interchangeability Rl 103-1969 Ball couplings for caravans and light trailers Rl 104-1969 Surface active agents — Technical sodium alkyl- sulphonates — Method of analysis Rl 105-1969 Pesticides considered not to require common

names — Second list R 1106-1969 Recommended practice for radiographic inspection of fusion welded butt joints for steel plates up to 50 mm (2 in) thick Annex to ISO-R 947, Explanations on the significance of the principal 1027,1106 radiographic terms used in ISO Recommendations concerning welding Rl 107-1969 Netting for fishing— Basic terms and definitions Rl 108-1969 Spices and condiments— Determination of nonvolatile ether extract Rl 109-1969 Classification of dense refractory products

Rl 110-1969 Plastics— Accelerated conditioning of test spec- imens of polyamide 66, 610 and 6 Rill 1-1969 Cold-reduced tinplate and cold-reduced black- plate— Part 1 — Sheet
ISO RECOMMENDATIONS 89

TABLE 13. Numerical List — ISO Recommendations — Continued

Ref. Title Rl 1 12-1969 Horology — Functional and non-functional jewels

Rl 113-1969 Representation of 6 and 7 bit coded character

sets on punched taped

R1114-1969 Cocoa beans -Cut test Rl 115-1969 Finishes with external screw thread for glass containers and gauges for the inspection of screw closures Rl 1 16-1969 35 mm and 16 mm microfilms, spools and reels Rl 117-1969 Bonded abrasive products — Grinding wheel

dimensions — Part 2 Rl 118-1969 Chemical analysis of aluminum and aluminum

alloys— Determination of titanium (Spectrophotometric method with chromotropic acid) R 1 1 1 9- 1 969 Series of conical tapers and taper angles

Rl 120-1969 Strength of mechanical fastenings for conveyor

belts (Static test method)

Rl 121-1969 List of characteristics which may be required

of conveyor belts according to their use Rl 122-1969 Glossary of gears — Geometrical definitions Rl 123-1969 Rolling bearings -Tapered roller bearings- — Inch series — Chamfer dimension limits Rl 124-1969 Sampling bulk shipments of carbon black for the rubber industry

Rl 125-1969 Determination of ash content of carbon black

for the rubber industry

R 1 1 26- 1 969 Determination of loss on heating of carbon black

for the rubber industry

Rl 127-1969 Stainless steel tubes — Dimensions, tolerances and conventional masses per unit length

Rl 128-1969 Steel tubes -Butt welding bends 5 D (90° and

180°) Rl 129-1969 Boiler tubes- Dimensions, tolerances and conventional masses per unit length

R 1 1 30- 1 969 Methods of fiber sampling for testing Rl 131-1969 Weft pirns for box loaders for automatic looms —

Dimensions of pirn tip Rl 132-1969 Rolling bearings — Tolerances— Definitions R1133-1969 Plastics -Determinafion of the melt flow rate of thermoplastics

Ref. Title Rl 134-1969 Pears — Guide to cold storage Rl 135-1969 Transfusion equipment for medical use Rl 136-1969 Air permeability methods for measuring the mean diameter of wool fibres Rl 137-1969 Plastics -Method of test for the determination of

the behaviour of plastics in a ventilated tubular oven R 1 1 3 8- 1 969 Determination of total sulphur content of carbon

black for the rubber industry

R 1 1 39- 1 969 Texfiles - Designation of yarns R 1140-1969 Three-strand polyamide multifilament ropes Rl 141-1969 Three-strand polyester multifilament ropes Rl 142-1969 Sampling and conditioning of ropes for testing R 1 1 43- 1 969 Rotating bar bending fatigue testing Rl 144-1969 Texfiles — Universal system for designafing

linear density (Tex system) (Replacing

ISO/R 138andISO/R271)

R 1 1 45 - 1 969 Dimensions of refactory arch bricks R 1 1 46- 1 969 Pyrometric reference cones Rl 147-1969 Plastics — Aqueous dispersions of polymers and

copolymers — Freezethaw cycle stability test Rl 148-1969 Plastics — Polymer and copolymer water dis- persions—Determination of pH

R 1 1 49- 1 969 Layout of multilingual classified vocabularies Rl 150-1969 Closed-end drop wires (electrical and mechanical) for automatic drawing-in machines

Rl 151-1969 Symbols for flight dynamics- Part I -Aircraft motion relative to the air R 1 1 5 2- 1 969 Symbols for flight dynamics - Part 1 1 - Motions

of the aircraft and the atmosphere relative to the earth Rl 153-1969 Symbols for flights dynamics- Part IllDerivatives of forces, moments and their coefficients Rl 154-1969 Dimensions for punched paper tape for data

interchange

Rl 155-1969 The use of longitudinal parity to detect errors in information messages Rl 156-1969 Shipbuilding details -Wrought aluminum alloys for use in shipbuilding
17. STEEL

ISO Technical Committee on Steel, ISO/TC 17, has developed 70 ISO

Recommendations (counting each part as a separate document) including 17

that are dimensional standards. The dimensional standard (1SO/R388) for thicknesses of sheet metal and diameters of wire summarized in table 6 and

discussed in II. 4.1 is applicable to all metals including steel and hence was

developed by another technical committee. Likewise, pipe dimensions

(ISO/R65) in table 8 and 1 1 .5.2 is under the cognizance of ISO/TC 5 which

deals with pipe and fittings made from any material. ISO/R65 and other pipe

standards are discussed more fully in a subsequent section of this survey. Most ISO Recommendations for steel are specifications for chemical

composition and/or physical properties, or are test methods for steel. Chemical composition is generally expressed in percentages. Therefore, measure- ment units are not involved. Test methods for chemical composition usually

employ customary metric units. Measurements units are generally involved

in the specifications and test methods for physical properties, but they are

easily translated into other units. The American ( ASTM), British (BS), French (AFNOR), German (DIN),

Italian (UNI), Japanese (JIS), and Indian (IS) national standards cor- responding to the 70 ISO Recommendations for steel are listed in table 14. Prior to 1962, the U.S. apparently expressed little interest in international

steel standards since the U.S. did not vote on 21 of the fu st 27 ISO Recommendations listed in table 14. From 1964 through 1969, there were 43 ISO

Recommendations issued of which the U.S. approved 25, and disapproved

13. The ISO Recommendations approved by the U.S. generally differ from

the corresponding ASTM standards. The U.S. Committee for International

Standardization of Steel is part of ASTM Committee A- 1 on Steel. In view

of the greater interest recently in international standardization, this Commit90
STEEL 91

tee may take steps to bring ASTM standards in accord with ISO Recommendations approved by the U.S.

Of the 17 dimensional standards for steel products, five are metric series,

four are inch series, seven are for railway rolling stock and one includes both

metric and inch products. The U.S. disapproved only those for railway

rolling stock. Thus, the disapprovals of dimensional standards are not based on measurement units per se, but on more basic differences in engineering

practices. On the other hand, approval of the metric dimensional standards

does not make them part of U.S. practices. In order to do so, it is necessary

to adopt new national standards or revise existing ones and industry must

use them in their manufactures.

TABLE 14. International Steel Standards

ISO U.S. U.K. France Germany Italy Japan India Rec. (ASTM) (BS) (AFNOR) (DIN) (UNI) (JIS) (IS)

79 A370, ElO *240 * A03-152 * 50351 Z2243 * 1500

80 A370 ^891 * A03-153 * 50103 *5550 Z2245 * 1586

81 E92 *427 * A03-154 ^50133 Z2244 * 1501 82 A370 M8 A03-151 '50145 (') * 1608

83 A370 * 131 A03-156 ^501 15 (') * 1499 84 A370 * 131 *501 15 (') * 1598

85 A370 * 1639 A03-I57 1605 ' 1599 86 E8 * 18 A03-160 *501 14 ''5547 Z224I '' 1 663

87 A370 * 1639 A03-158 1605 *5548 Z2248 * 1962 88 * 1639 A03-159 *50153 *5549 Z2550 * 1403 89 A318 A03-701 ^51210 {') * 1521 136 A3 18 A03-701 *5I212 {') "-1717 144 *2803 A03-701 51211 C) * 1716

145 A326 A03-701 51215 («) * 1755

146 E92 427 A03-504 B7725 *1754

147 A370 *82 A03-501 51300 *6326 B7721 * 1828

148 A370 * 131 A03-i61 * 501 15 ' 47 1 3 C) '' 1757

149 *3855 A03-652 * 50 101 B7777 * 1756

156 A370 *240 * A03-502 B7724 *2281

165 A370 A03-855 '50139 * 5467 (.0) *2330

166 ' 1775 A03-856 * 501 35 * 5466 (") ^2335

167 A370 A03-852 * 501 36 -' 5469 ('-) *2329

202 A370 * 1775 A03-853 '50136 ''5468 (,3) *2328

203 *3500 501 18 '5111 Z2271 *3407

204 E139 *3500 A03-352 501 18 *51 1 1 Z227I * 3408

205 *3688 A03-351 501 12 *3918

206 E150 3500 A03-353 *511t Z2272 *3409

373 *3518 50100

374 A370 * 501 37 G346I-3

375 A370 * 18 A49-851 ^50140 * 5465 r) * 1894 376 E74 * 1610 51301 B7728

377 A370 A03-1 1

1

50125 * 6453 G0303 371 1 404 A6 * A03-1 15 G0303 1387 437 E30 * 122! ^ A06-301 *6454 G121

1

228 439 E30 * 1 121 ' A06-302 ^ 6442 228 442 A370 * 1310 *51222 B7722-3 ^3766

629 E212 * A06-303 G1213

422-764 OL - 71 - 7
ENGINEERING STANDARDS

TABLE 14. International Steel Standards — Continued

ISO U.S. U.K. France Germany Italy India Rec. (ASTM) (BS) (AFNOR) (DIN) (UNI) (IS)

630 A36 M360 A35-501 1 7 1 00 G3101 226, 1977 640 A370 *427 A03-507

642 A255 4437 A04-303 50191 G0561 *3848

643 El 12 A04-102 G5551 *2853

657/1 A575 A45-009 1028 G3192

657/II A575 A45-010 1029 G3192

657/11! 675/lV

657/VIl,... -

657/IX

671 E30 A06-304 *6460 G 1 2 1

*228

674 A370 ' 89A03-506 5 1 303 *3754

683/1 *970 A35-562 17200 G4051

683/11 A542 17200 G4051

716 E18 * 89

A03-503 *3804

726 ElO *240 A03-505 *4132

783 *3688 A03-351 501 12 M713

1005/1

1005/11

1005/111... 1005/lV ... 1005/V

1005/ VI ... 1005/Vll.. 1024 A03-170 *5072

1035/1 A45-003 ' 1013 * 60 1

G3191 *1732

1 O'? S/ 1

J U 1 4 uU 1 J I / iZ

1035/111 ... A45-005 1017 *6014 G3194 *1731

1052 A35-501 17100

1079 *5073

1099 50100 *5074

1 1 1

A36-150 * 1993

1 143 *5075

'Z2201, Z:24l. »G35:i. G3530, G3560.

2Z2202. Z2242. « Z2202, Z2242.

»Z2202, Z2242. G3437, G3461.

<Z2204, Z2248. "G3437, G3454. G3452, G3456. G3461, G3463.

5Z2201, Z2241. G3452. G3454. "G3521, G3.<i36, G3530, G3560. '•iG3441. G3444. G3452, G3458, G3460.

' C2506, C3 1 26. " Z220 1 , Z224 I

* Essentially in agreement with ISO Recommendations; agreement with Japanese (JIS) standards was not determined.
18. NONFERROUS METALS

ISO Recommendations for nonferrous metals are developed by three

technical committees: TC 18 Zinc and Zinc Alloys, TC 26 Copper and

Copper Alloys and TC 79 Light Metals and their Alloys. These committees

developed 61 ISO Recommendations which were issued from 1959 through

1969. Only one {ISO/R431) is a dimensional standard. Other dimensional

standards are in draft recommendation stage. Dimensional standard for thicknesses of sheet metal and diameters of wire (ISO/R388) and dimensional standards for pipe and tubing developed by other committees are also

applicable to nonferrous metal products.

The American (ASTM), British (BS), French (AFNOR), German (DIN),

Italian (UNI), Japanese (JIS), and Indian (IS) national standards cor- responding to the 61 ISO Recommendations on nonferrous metals are listed in table 15. There are ASTM Standards corresponding to 52 of the 61 but

there may be substantive differences. There appears to have been little or no

effort made to revise ASTM Standards to be in essential agreement with the

ISO Recommendations that have been approved by ANSI. Generally, SI

units have not been included, other than the inclusion of a conversion table added as an appendix to the standard.

ASTM Committee B-2 on Nonferrous Metals and Alloys, B-5 on Copper

and Copper Alloys and B-7 on Light Metals and Alloys have the U.S. advisory committees for ISO/TC 18. 26, and 79, respectively. The activity of

the three ISO committees and the U.S. participation on them is reflected in the following tabulation of voting by ANSI on the 61 ISO Recommendations for Nonferrous Metals.

93
94 ENGINEERING STANDARDS

Number of ISO Recommendations

Committee Approved Dis- No vote Total approved

18 6 1 1 8 26 4 7 5 16 79 30 3 4 37

40 1

10 61

Thus, about 65 percent of these ISO Recommendations appear to conform

sufficiently well with U.S. practice to warrant approval, even though they

may differ to some extent from ASTM Standards. Measurement units do not appear to underlie either the approval or disapproval votes of ANSI.

TABLE 15. International Standards for Nonferrous Metals

ISO U.S. U.K. France Germany Italy Japan India

1 IVI f V /A r IN Kj IV f rl IN 1

(IIS)

1 14 B92 *2970 * 17800 *5537 H2150

115 B179 A57-I01 * 1712 2590

121 894 *2970 *1729 H5203

122 893 *2970 *1729 H2221

164 885 1490 A57-702 *1725 *5470 H5202 617

190 E8 *18 *50145 Z2241 *1816

191 ElO *240 *50351 *1790

192 E92 *427 *50133 *1810

195 8153 n *50I35 {') *2348

196 8154 (') *5091

*3669 H3422-5 *2305

197 B224 A53-100 *1718 *5649

207 892 * 17800 *5537

208 885 *1490 A57-702 *1725 H5202 617 209 8221 ("') *1712 737

301 8240 *1004 A55-102 *1743 H2207 713 397 *2873 51212 *3388

398 *1639 (-) *3260

399 E92 *427 *50133 *2866

400 E8 *18 *50145 (') *2654

401 E8 *I8 *2655

402 E8 *18 51210 (') *2656

403 EiO *240 5035 1 *3054 426 (") A5 3-403 * 17660 {') 427 8103 ('-) A53-012 * 17662 428 8150 * 17665 H3441

429 8151 ('') * 17664 (") 430 B151 * 17663

431 B712 *1036 1708 H4121-2 191 503 8107 3370 1729 H4201-4

713 E68 *A06-814 *406 714 E40 *3630 *A06-813 *406

715 *3630 *A06-814 H2107 *2600

752 A55-101 *i706 *209
NONFERROUS METALS 95

TABLE 15. International Standards for Nonferrous Metals — Con.

ISO U.S. U.K. F" rsncc \JCi illaliy 1 lal y J cip^n 1 nuiH

\ 1 ivi / \r\r KJ i\ 1

791 E35 *3907 *A06-591

792 E35 *3907 * A06-593 *5893

793 E34 * 1728 *A06-571 *504

794 E34 *3907 *A06-592 *5895

795 E34 *A06-572

796 E34 *A06-572 *5894

797 E34 * 1728 *A06-570 *5892 *504

798 E34 *1728 A06-573 *5896 *504

807 *A06-594 *6137

808 E35 A06-570 *504

809 E35 *3907 *A06-597

810 *3907 *A06-597

826 B209 1745 (') *736-7

827 B221 1746 H4172-3 *1285 828 B316 59675 H4465-7 *740 829 B247 1749 H2103

886 E34 * A06-576 *504

952 E8 *2657

953 B2 10 *4599

954 E290 *4598

955 *4177 956 E8 *2658

957 E143 *4176

958 B230 *4168

1053 *A06-801 *2600

1054 E68 *A06-814 *2600

1055 *A06-823 406, 2600

1118 E34 *A06-574 504

'H3631, 3641. 3651, 3661. 2Z2204. 2248, 'Z2201,2241, <H3201-3. 3220, 3321-2, 3325, 3422-5, 3521. 3523, 3631.

= H3731-2, 3741-2. 'H3701-2, 371 1. 3721.

' H4 101. 4104-6, 41 1 1, 4121-3, 4161, 4163-7, 4181-3. "Agrees with BS378, 659, 885. 1386. 1464. 2017, 2871. "Agrees with BS250-2. 378, 885, 1464. 1867. 1948, 2579, 2871. 2874. '"Agrees with BS1470-1477.

" BS218, 249-52, 265-67, 378, 409, 711-13. 885, 1464, 1541, 1949, 2579, 2786, 2870-75. I2BS369, 407, 2870-1. 2873-5. "BS378, 1067, 1464, 2032-3, 2579, 2870-5. "BS374,378, 1464,2579,2870-1,2875.

"^Agrees with BS790, 2870. 2873. "ASTM B36, B121, B140, B453. B455.

'Essentially in agreement with ISO Recommendation; agreement with Japanese (J IS) standards was not determined.
19. PLASTICS

There have been 69 ISO Recommendations issued through 1969 that were developed by ISO/TC 61 on Plastics. This committee is one of the

most active in ISO. The secretariat is held by the American National Standards Institute. U.S. participation in this committee is through a National

Committee under the cognizance of Committee D-20 on Plastics of the

American Society for Testing and Materials.

The 69 Recommendations on plastics pertain to methods of test, ter- minology, symbols, etc. There is no quality specification or dimensional

standard among the 69 so far issued. However, there are dimensional standards for plastic pipe which were developed by another ISO committee and

which are discussed in a subsequent section of this survey. The American (ASTM), British (BS), French (AFNOR), German (DIN),

Italian (UNI), Japanese (JIS), and Indian (IS) standards corresponding to the 69 ISO Recommendations on plastics are listed in table 16. Twenty-three

of them are essentially equivalent to corresponding ASTM standards

and seven are similar. It is evident from table 16 that some other countries have more national standards in accord with the ISO Recommendations than the U.S. has even though the Secretariat of ISO/TC 61 is in the

U.S. These countries generally had few national standards for plastics and

they adopt the ISO Recommendations for the national standards as they are

issued. ASTM standards for plastics generally include metric equivalents of

U.S. customary units. However, most standards do not permit easy use in laboratories having equipment calibrated in metric measurement units.

96
PLASTICS 97

TABLE 16. International Standards for Plastics

ISO U.S. U.K. France Germany Italy Japan India Rec. (ASTM) (BS) (AFNOR) (DIN) (UNI) (JIS) (IS)

59 D494 '2782 *T5 1-004 '53700 1 M273 *867

60 *D1895 *2782 T5 1-003 '53468 ''4267 K691

1

*867, 2221

61 *D1895 *2782 *T5 1-003 * 53467 '4268 K691

1

62 *D570 *2782 *T5 1-002 ^53475 ''4292 K6790 (') 75 * D648 '2782 'T5 1-005 ''53461 *564I '- 867

117 D570 *2782 T5I-0]

1

* 53471 ''4293 K691

1

'2221

118 ^2782 T5 1-006 *537I8

119 *2782 *T51-010 * 53704 *4297 *867

120 *2782 T5 1-009 '53707 M299 ''867 171 *D1895 '2782 'T51-012 * 53466 -'4270 K691

1

'*867,

^ 2221,

172 *T5 1-008 "53708 -4298

173 *2782 *T5 1-007 *537I9

174 D1243 *2782 T51-013 ''53726 K6721 ' 4669

175 ' D543 ^T5 1-029 * 53476 *6059 K6761 '2798

176 D1203 * 53407 "5636 K6733

177 *T5 1-025 * 5 3405 ^5638

178 *D790 *2782 T5 1-001 179 *D256 *2782 T51-035 ^53453 * 6062 K691

1

180 *D256 *6323 K691

1

(') 181 *D757 *2782 T51-015 '53459 *5639

182 D793 * 53381 '*4669 183 *2782 'T5 1-028 ''53415 *6064 '2076

194 '7730 '5806 K6900

291 * D6 1

8

*T5 1-014 50014 '4301 (-') 292 ' D1238 ' T51-016 53735 K6760 2530

293 D2292 ''2530 294 D1897

295 D796 *53451

305 *53381 *5637

306 *DI525 *2782 T5 1-021 * 53460 *5642 ''2530 307 ^•2782 T51-019 ''53727 K6810

308 ' 2782 *T5 1-020 *53710 -4296 * 867 458 *D1043 T51-102 '53447 *5635

462 D543 T5 1-023 ;*53476 1 * 6060

472 D883 * 1755 '4266 K6900

483 *E104 3718 489 *D542 T5 1 -064 53491 K67I4

527 *D638 T5 1-034 ''53445 ''5819 K691

1

(') 537 *D2236 T51-104 * 53445

584 D1043 *T5 1-022 * 1 6945 *5814 K6901

585 T5 1-350 *53723 *5644 K6791

599 K6810

600 *D789 T5 1-032 *53728 K6810

604 * D695 T51-101 K691

1

800 K6915 1300 844 D1621 *T56-101 * 53421 K6967

845 D1895 -T56-107 * 53420 K6767

846 D1924 X41-513

868 * D2240 K6888
gg ENGINEERING STANDARDS

TABLE 16. International Standards for Plastics — Continued

ISO U.S. U.K. France Germany Italy Japan India Rec. (ASTM) (BS) (AFNOR) (DIN) (UNI) (JIS) (IS)

869 870

871 D1929

872 T51-351 *53724

877 E187 T5 1-055 *53388 *6063 K7101

878 D1499 T5 1-057 K7102

879 D2565 T54-012 *53389

899 D674 T51-103 * 5 3444

922 *5817

960 K6810

974 D746 *5812

1043 *7728

1060 *T53-001 *7746 K6720

1 OA 1

I J 1 —jjZ J J 1 1068 *T5 1-042 * 53 194 K6721

1110 *T5 1-051 * 537 14

1 133 D1238 *5640

1137 T51-161

1147 'T51-053

1 148 ^751-052

* Essentially in agreement with ISO Recommendation; agreement with Japanese (JIS) standards was not determined. **No separate standard. British Standards generally are in agreement. 'Agrees with 1S867, 2221, 2267.

2 Agrees with IS867, 1998. 2267. ^Agrees with IS867, 1998, 2221, 2530.
20. RUBBER

ISO/TC 45 on Rubber has developed 35 ISO Recommendations through

1969. They are either sampling procedures or methods of test. Dimensional

and quality specifications are to be issued soon. As indicated in table 7 and

11. 4. 2, the rubber industry has adopted preferred numbers for bore sizes of

rubber hose, but manufacture of such hoses has not yet been implemented

since ISO Recommendation R1307 was approved in late 1970.

The American (ASTM), British (BS), French (AFNOR), German (DIN),

Italian (UNI), Japanese (JIS), and Indian (IS) national standards cor- responding to the 35 ISO Recommendations for rubber are listed in table 17. There are ASTM standards essentially equivalent to 29 of them. This

number exceeds the number issued by other countries that are in agreement

with the ISO Recommendations listed in table 17. The high degree (over

80%) of agreement between ASTM standards and ISO Recommendations

for rubber exceeds that for any other ISO Committee including those whose

Secretariat is held by the American National Standards Institute. The acceptance of ASTM standards for rubber internationally stems from

policies early established by ASTM Committee D-11 on Rubber and

Rubber-Like Materials, the sponsor of the U.S. Committee advising ANSI

and representing the U.S. on ISO/TC 45. Committee D-1 1 encourages the

development of new methods with metric measurement units and early in- cluded metric units in existing methods. Perhaps of more significance. Committee D-1 1 has modified many ASTM standards for rubber to permit their use in both metric and nonmetric laboratories. These standards could be

readily edited for use by ISO and metric countries. In line with ASTM policy, Committee D-11 is currently including SI units or changing customary

metric units to SI units in standards that already include metric units.

99
100 RUBBER

TABLE 17. International Rubber Standards

ISO U.S. U.K. Fr3,ncc Gcrmsny Italy J3,p3n Rec. (ASTM) (BS) (AFNOR) (DIN) (UNI) (JIS) (IS)

33 D394 903A9 *T46-012 53516 ^5254 ' 3400

34 D624 903A3 *T46-007 *53515 K6301

35 *D1076 * 1672-2 *T42-012 * 53567 M902 K6381 *3708

36 *D413 *903A12 * T46-008 * 53530 K630I '3400

37 D4 1

*903A2 ^T46-002 * 53504 M915 K6301 '3400

48 ^DI415 *903A7 * T46-003 * 535 19 4046 K6301 ' 3400

*903A20

123 *D1076 1672-1 *T42-001 53562 ^4901 K6381

*D1417 3397

124 D1076 1672-1 ^742-003 53563 ^4903 K6381 *3708 *D1417 3397

125 *D1076 * 1672-1 *T42-005 53565 M904 K6381 *3''08 126 *D1076 * 1672-1 *T42-004 * 53564 ''5255 K6381 '3708

127 *D1076 * 1672-2 *T42-013 * 53566 ^5256 '3708

132 * 903 A 10 T46-015 * 53522

133 D7 1*903A1T46-016 * 53522

188 *D572 *903A19 *T46-004 * 53508 '5408 K6301 * 3400

*D573 * T46-005 * 5409

* D865 *T46-006

247 *D1278 * 1673-2 *T43-105 53568 K6352 '3660

248 *D1278 * 1673-2 *T43-104 *53526 K6352 ' 3660

249 = D1278 * 1673-2 *T43-109 *53527 K6352 '3660

250 D1278 1673-1 *T43-003 * 53525 K6352

289 D1646 * 1673-3 *T43-005 * 53523 K6300 *3660

471 ' D 1 349 'T40-101 *4905 K630] 3400

498 * 1672-2 T42-002 *53591 *5874

506 ^D1076 * 1672-2 *T42-016 * 53590 *5614 '3708

667 D1646 * 1673-3 *T42-004 *53524 K6300

705 ^D1076 1672-2 T42-015 *5615

706 *D1076 1672-2 *T42-010 *5875 K6381

*D1417 3387 K6387

812 *D746 *903A25 T42-018 * 53546 K6301

813 ^D429B 903A21B *T46-017 ^^5405 K6301

814 - D429A 903A21

*T46-017 * 5406 K6301

815 D395B ^903A6A *T46-01

'53517 M913 K6301

S 1 fs l\.o:>u 1 976 ' D 1 076 * 3397 *T42-009

D1417

1 124 D1900 *T42-102

1 125 *D1506 *T45-132 K6221

1 126 ' D1509 *T45-I31 *6070 K6221

1 138 ^D1619 *T45-133

'Essentially in agreement with ISO Recommendations; agreement with Japanese (JIS) standards was not determined. "No separate standard, but individual British Standards generally are in agreement.
21. ANTI-FRICTION BEARINGS

21.1 BACKGROUND

A bearing is a mechanical device used to reduce friction between parts of

a machine where movement occurs. Anti-friction bearings are bearings that employ rolling elements to minimize friction, such as spherical balls, cylindrical rollers, spherical rollers, and conical rollers. The bearing dimensions

are critical with respect to dimensions of parts of the machine in which they

are in contact. The use of bearings conforming to standardized dimensions

provides benefits both for the user and the manufacturer. The user benefits

from alternate sources of supply, greater availability of replacement

bearings, and lower cost. The manufacturer benefits from a smaller number

of items to be manufactured and kept in inventory. The standardization is confined to external dimensions and tolerances which are essential for in- terchangeability, generally as completely assembled bearings. Internal

design and dimensions are manufacturer's choice except in bearings assembled by the user from standardized parts.

21.2 STANDARDS FOR ANTI-FRICTION BEARINGS

National standards issued by the American National Standards Institute are based on AFBMA industry standards developed by the Anti-Friction

Bearing Manufacturers Association. International standards are developed

by ISO Technical Committee 4 on Rolling Bearings. Through 1969, this Committee developed the 30 ISO Recommendations listed in table 18. They

are mostly dimensional specifications for boundary dimensions and

tolerances of radial and thrust ball bearings, radial and thrust cylindrical

roller bearings, tapered roller bearings, and accessories for bearing installation.

101
102 ENGINEERING STANDARDS

TABLE 18. International Standards for Antifriction Bearings

ISO Rec. U.S. U.K. France Germany Italy Japan India (ANSI) (8S) (AFNOR) (DIN) (UNI) (JIS) (IS)

15 B3.6 '292 E2 2-300 ^616 4259 81512 '2513

76 *B3.1 1 *E22-391 622 81519 '3823

104 B3.6 ^^£22-300 616 6033 81512, 2513 81532

113 83.^E22-308 736-9

199/1 83.E22-359 620 81514 2513

199/11 83.

200 83.7 620 80104 2513

201 83.5 292 *E22-316 620 81 521 2513

246 E22-308 5412 81533

281 'B3.1 I E22-392 622 81518 '3824

300/1 854.1 *E22-395 '5417 81516 2398

300/11 854.1 81516

300/111 355/1 83.

*E22-300 616 ' 6034 B 1 5 1

'3697

3SS/II E22-300 616 81 534

355/111. .. 3134 E22-300 616 355/lV *3697 355/V E22-300

464 83.6 'E22-302 616 6046 81509 '2513 465 83.6 E22-316 '620

492 83.5 E22-316 620 4505 81514 '2513

533 83.5

577/1 ^E22-335 620 4223 81514 '3697

577/11 81514

578 83.5 3134

582 83.5 620 4597 81566 *3697

1002 1038 620

1 123 1132 BO 104

"Essentially in agreement with ISO Recommendation; agreement with Japanese Standards (JIS) was not determined- The American (ANSI), British (BS), French (AFNOR), German (DIN),

Italian (UNI), Japanese (JIS), and Indian (IS) national standards cor- responding to the 30 ISO Recommendations are listed in table 18. The U.S.

approved 23, disapproved one, approved one in part, and did not vote on

five. The U.S. and ISO standards for identification code and load ratings are

in complete agreement. The dimensional specifications for metric ball bearings are in accord except for the chamfer. The AFBMA chamfers are consistent with the ISO chamfers, but some bearings conforming to the ISO

chamfer would not meet the chamfer requirement in the ANSI Standard.

Although the preponderance of ball bearings made in the U.S. conforms to the ISO metric series, there are many ball bearings made in an inch series,

such as airframe bearings, and some even made in mixed inch and metric

dimensions. For example, the bore may be a multiple of 1/16 inch and the

outside diameter may be a whole number of millimeters or the bore and outside diameter may be a whole number of millimeters and the width a multiple
ANTI-FRICTION BEARINGS 103

of 1/16 inch. There are also proprietary ball bearings of nonstandard dimensions made for use by equipment manufacturers who desire to restrict trade. Dimensional specifications for cylindrical roller bearings are similar to those for ball bearings. The metric series conform to the ISO Recommendations except for chamfer. Cylindrical roller bearings classified as needle

bearings, those used in airframes, and proprietary cylindrical roller bearings

are made in inch series. There is no U.S. standard for metric series of tapered roller bearings.

Production of a metric series has started in the U.S., but the dimensions do

not conform to ISO Recommendations for tapered roller bearings. The inch

series of tapered roller bearings include many more sizes in the U.S. standards than in the ISO Recommendations. This situation exists because the

bearing manufacturers make special sizes at the request of equipment manufacturers using tapered roller bearings. The change to a metric series should

eliminate the numerous inch sizes developed over the years and reduce cost of manufacture and inventory.

ISO Recommendations for spherical roller and instrument precision ball bearings are under development.

The Anti-Friction Bearing Manufacturers Association estimates that 60

percent of the anti-friction bearings made in the U.S. are in metric series

conforming to ISO Recommendations. Now that tapered roller bearings are being made in metric series, this percentage made in metric sizes should be

increasing. The U.S. is an active participant in ISO/TC 4 on Rolling

Bearings and U.S. standards are generally in essential agreement with the

ISO Recommendations. The dual inch and metric series increase the

number of bearings manufactured and inventoried in the U.S. and hence

cause a needless increase in cost.
22. BUILDING CONSTRUCTION AND

MATERIALS

ISO Recommendations pertaining to building construction and materials

originate in many technical committees. General purpose products such as pipe and structural steel are used much more widely than in buildings and are discussed in other sections of this report. The following technical committees are concerned primarily with building construction or materials for buildings:

55 Sawn timber

59 Building construction

77 Products in asbestos cement

89 Boards made from wood or other ligno-cellulosic fibrous materials

92 Fire tests on building materials and structures 99 Semi-manufactures of timber

1 16 Performance testing of space heating appliances

Some activities of other committees, such as TC 43 on Acoustics andTC

74 on Hydraulic Binders, also pertain to buildings. The combined activities of the technical committees dealing exclusively or in part with building construction and materials has resulted in 60 ISO Recommendations through

1969. Sixteen of these ISO Recommendations relate to pipe and structural

steel. The remaining 44 are listed in table 19 together with corresponding

American (ASTM), British (BS), French (AFNOR), German (DIN), Italian (UNI), Japanese (JIS), and Indian (IS) national standards. The U.S. ap- proved seven, disapproved four, and did not vote on 33 of these 44 ISO

Recommendations. The 1 1 votes pertained to ISO Recommendations

developed by technical committees 43, 74 and 77. Among the other six committees mentioned above, U.S. participates only in 59 and 92 but did not

104
BUILDING CONSTRUCTION AND MATERIALS 105

TABLE 19. International Standards for Building Construction

and Materials

ICO I T C U.K.. France Germany Italy Japan India Rec. (ASTM) (BS) (AFNOR) (DIN) (UNI) (JIS) (IS)

140 (') *2750 S3 1-002 *52210 Z8106

160 P4 1-302 * 19800 4372 A5301 *1592

390 P08-00I

391 C428 19830 6159

392 C428 19831 6159

393 P33-30I 274 3949 A5403

394

395 P33-302 274 3948 A5410

396 274 3948 A5410 *2096

597 C219 P15-101 '

1 164 631 *4050 B54-008 280 4373

679 C109 PI 5-45 I 1 164 6132-3 *4031 680 PI 5-461 M 1 64

681 CI 14 ^1 164 682 CI14

717 S31-010 4109

737 68250 2179

738 (-) 68251 1331 766 D1037 851-101 52350- *5064 1658 767 D1037 851-102 52351 *5066 2380

768 D1037 851-107 52352 *5067 2380

769 D1037 851-104 52351 *5068 2380. 1658 818 D1554 851-100 68750 *5062 1658 819 D1554 851-103 52350 * 5065 1658, 2380

820 D1554 851-200 52360 4867 3087, 3097, 3478

821 D1037 851-201 52361 4866 2380

822 D1037 851-203 52361 4870 2380

823 *D1037 351-202 52361 4871 2380

834 *E119 P92-201 M102 *3809

863 C340 PI 5-462 1 164 *4032

880 247 3948

881 PI 6-403 19830 5341 1006 e) PO 1-001 4172 *1233

1029 850-002 707

1030 (-) *3364

1031 850-002 3364

1032 850-002

1040 4172

1046 P02-001 1356 *962

1047 P02-002 1356 *962

1072 '854-150 280 4373-5

1096 851-340 6469

1097 * 854-155 6470

1098 6472

' ANSI Standard Z24.19.

- Commerce Standard PS 20.

^ ANSI Standards .^62.1 and A62.5.

" Agrees substantially with ISO Recommendations; agreement with Japanese Standards (JIS) was not determined.
106 ENGINEERING STANDARDS

vote on the ISO Recommendations developed by any of these committees.

In view of this small participation, it is not surprising that U.S. standards for building construction and materials are generally not in accord with the ISO

Recommendations. U.S. indifference toward international standardization

in the building industry may stem from the fragmentation of standardization

within the U.S. among some 6,000 local building codes and regulations.

A basic ISO Recommendation for building construction is R1006 which

establishes a basic module of 10 centimeters. For countries using the yardfoot-inch system, the basic module is 4 inches. ISO Recommendation

R1006 was issued in 1969 and is beginning to be incorporated into national

standards. It is being supplemented by other recommendations establishing

multimodules for horizontal and vertical dimensions of buildings. If these

recommendations are followed in countries approving them, they would

become the foundation for standardization of building construction that should result in substantial reduction of building costs. Present trends in- dicate that the basic module of 4 inches is not likely to be used except in the

U.S.
23. PIPE AND TUBING

23.1 BACKGROUND

Tubing having outside diameters conforming to one of the sizes listed in ANS B36.10 issued by the American National Standards Institute is generally called pipe. Other sizes retain the designation tubing. The agree- ment noted in table 8 for outside diameters of U.S. and ISO pipe sizes (with

two exceptions previously noted) reflects international standardization oc- curring many years ago. Present outside diameters of pipe can be traced to the English tube trade during the period 1820 to 1840. In 1886, the Committee on Standard Pipe and Pipe Threads of the American Society of Mechanical Engineers published (Transactions ASME, Vol. 8, p. 40) the dimensions

for standard wall pipe that are now in ANS B36.10. Since all pipe was

originally threaded, standardization of outside diameters was critical. The

wall thickness was not critical provided it was sufficient to permit threading

and still have adequate strength. As a consequence, there has not been

universal agreement on wall thickness.

Standardizing committees have used at least four equations for relating

wall thickness (T), outside pipe diameter (D), pressure (P), and stress (S). Currently, the following equations for determining thickness of pipe appear

in various standards:

These equations are arranged in descending order of wall thickness; that

is, eq (1) gives the greatest thickness and eq (4) gives the least. Equation (1)

T = 0.1 + DP/1.75S

T= DP/2S

T= DP/(2S + 0.8P)

T= DP/(2S + P)

(1)

(2)

(3)

(4)

422-764 OL - 71 - 8 107
108 ENGINEERING STANDARDS

applies only when the inch unit is used; the other equations are applicable

when any unit is used consistently. The actual values specified in most standards for wall thickness are not consistent with values calculated from the

given equation. The specified wall thicknesses usually give pressure ratings for the pipe which decrease with increasing diameter. The notable exceptions are some relatively recent standards for plastic pipe having a constant

ratio of D/T (Standard Dimension Ratio).

The diverse practices used in developing standards for pipe and tubing

stems from independent committees in the U.S. and most countries for pipes

and tubing made from different materials. Within ISO, a single technical

committee deals with pipe and tubing regardless of the material. Fittings are

also the responsibility of this committee, ISO/TC 5 on Pipes and Fittings.

(Note: In 1970, Subcommittee 6 became iSO/TC 138 Plastic Pipe and

Fittings).

23.2 SPECIFICATIONS

Table 20 lists the 25 ISO Recommendations developed through 1969 by

ISO/TC 5 and the corresponding American (ANSI), British (BS), French

(AFNOR), German (DIN), Italian (UNI), Japanese (JIS) and Indian (IS)

national standards. The U.S. did not vote on 23 of the 25 ISO Recommendations, and disapproved two. Table 20 includes ISO Recommendations R7

and R228 on pipe threads which are discussed in section 24 on screw

threads and fasteners. Pipe and tubing dimensions are prescribed in the following ways in domestic and international standards:

1. ISO Recommendations and most domestic standards specify the

outside diameter and wall thickness with tolerances on each.

2. A few domestic standards specify the inside diameter and wall

thickness with tolerances on each.

3. A few domestic standards specify the outside diameter with

tolerances, the minimum inside diameter and the minimum wall

thickness.

The outside diameter corresponding to a given nominal size may have any

one of the following values:

1. For pipe sizes up to 12 inches, the outside diameters are larger than

the nominal sizes and have the values indicated in table 8. 2. The outside diameter of some tubing, particularly that for water ser- vice, is 1/8 inch larger than the nominal size.

3. Pipe sizes over 12 inches and most tubing have outside diameters

equal to the nominal sizes.

4. Tubing having inside diameter and wall thickness specified has an

outside diameter dependent on these dimensions.

The tolerance on pipe and tubing vary widely. Table 21 gives the

minimum and maximum limits for outside diameter of five sizes of pipe given
PIPE AND TUBING IQQ

TABLE 20. International Standards for Pipe and Tubing

ISO U.S. U.K. France Germany Italy Japan India Rec. (ANSI) (BS) (AFNOR) (DIN) (UNI) (J IS) (IS)

7 B2.1 *(') E03-004 *2999 *339 B0203 *554

13 B16.1 *1211 28501 *5336 G5523 * 1536-8

49 BI6.3 *143, 1256 *2950 *5192 B2301 *1879

50 B16.5 *1387, *E29-029 *2886 *349 B2302

1740

64 B36.10 *(-) *A49-004 *(•') *4991 G3452 *1 161 65 B36.10 *1387 * 2440-1 *3824 G3452 *1 161, 1239

134 B36 *A49-004 *(') *4992 G3444 3601

161 3867 T54-002 *V)

->~>

J *(.)) *4991 G3452 *1161 228 *2779 E03-005 *259 *358 B0202 *2232, 2643 264 *8063-8

265 T54-017 *19531 K6743

274 A68-201 *LN9494 e) *2501

285 B16.9 *1965 E29-043 *2605 *5788 B2304

330 K674I-2 *3076

336 536, 5601 *A49-004 *(') *4991 (") 1 161 508 1710 2403 5634 Z9102 *2379

531 416 3989

559 1336.1 *6363 (') 3589

560 *A48-003 *2391 *2898

580 *8063

727 T54-029 *8063

1127 *A48-051 G3459

1128 *E29-045

1129 G3461-2

' BS 21, 143. 1256 and 1740.

- BS534, 778, 1965. 3601 and 3602.

" DIN 2448 and 2458.

^ DIN 8061, 8062, and 8702-5.

= JIS H3601, 3620, 3631, 3641, and 3651.

= JIS G3452, 3454, 3455-7, 3461-2, 3464, 3437, and 3444. 'JIS G3452. 3457. "JIS G3452. 3454-6.

*Essentially in agreement with ISO Recommendation; agreement with Japanese (JIS) standards was not determined.

in ISO Recommendation R65 for steel pipe and in various ASTM standards.

The letter in the designation signifies the material; i.e., A-ferrous, B-nonferrous, and D-plastic. This table represents only a portion of the domestic

standards for pipe, but it is typical of the various limits specified for a critical dimension required to be maintained for both nonthreaded and threaded

fittings. The tolerances on outside diameter of tubing range from 0.001 to 0.023 inch for 3/4-inch tubing and from 0.002 to 0.03 1 inch for 3-inch tubing.

An occasional standard permits only plus tolerances or greater plus than

minus tolerance. Plus tolerances, particularly of different magnitudes, makes

the standardization of fittings difficult for either pipe or tubing.

Table 8 shows that wall thickness is the principal difference between ISO

and U.S. pipe. This dimension is also the principal difference among

domestic standards. Table 22 lists the wall thicknesses specified for 6-inch
110 ENGINEERING STANDARDS

TABLE 21. Limits on Outside Diameter of Pipe

Nominal size inch mm 20 Wi

40

380

615012 300

1.075 1.921 3.524 6.555 min 1.043 1.886 3.465 6.453

Note 1 IT13,X 1.066 1.916 3.535 6.691 12.878 mm 1.019 1.869 3.465 6.559 12.622 msx 1.065 1.916 3.531 6.687 12.843

1.019 1.869 3.469 6.594 12.719 DH^, DHj, DJ>iJ 1.050 1.900 3.500 6.625 12.750 min 1.044 1.894 3.490 6.609 12.726 BI6I . B165 max 1.055 1.905 3.510 6.640 min 1.045 1.895 3.490 6.610 B188. B302 max 1.050 1.900 3.500 6.625 12.750 min 1.045 1.894 3.492 6.61

12.732 Note 2 max 1 .058 1.908 3.5 10 6.645 min 1 .042 1.892 3.490 6.605 B466. B467 max 1 .053 1.904 3.505 6.634 12.765 min 1 .047 1.896 3.495 6.616 12.735 Note 3 max 1 .054 1 .906 3.508 6.636 12.765 min 1 .046 1.894 3.492 6.614 12.735 D2310, D2517 max 1 .065 1.915 3.5 1

6.640 1 2.775 min 1.035 1.885 3.485 6.610 12.725 D2661 max 1.915 3.520

D2680

D2729, D2751

min max

min max

min

1.900 3.500

14.13

14.01 12.518 12.482

3.258 3.2426.286 6.264

'Medium and heavy series, two sets of other tolerances are given for light series I & II. Note I. ASTM A53, A72, AI20, B24I, B345, and B429 (Tolerances in some Standards are smaller by 0.001 inch). Note 2. ASTM BI67, B407, B423. B444, and B445. Note 3. ASTM D1503. D1527, DI785, D224I, D2282, D2446, D2447, D2513, D2665. and D2672.

pipe in ASTM standards. Over 30 nominal thicknesses are specified in the

range from 0.109 to 0.884 inch. Because of differences in specifying

tolerances, this number is increased to about 50. The thicknesses for steel pipe specified in ISO Recommendation R65 (0.192 inch for Medium and

0.212 inch for Heavy) correspond approximately to the two thinnest wall

thicknesses in ANS B36.10 (0.188 and 0.219 inch). These thicknesses are not commonly used in the U.S. and are not specified in the ASTM Standards. On the other hand, ISO pipe apparently is being used successfully in threaded application. It therefore appears that considerable economic

benefit could result from a reevaluation of the thickness requirements for standard wall pipe. \ The wall thickness of tubing specified in many standards can be traced to the Stubs gage numbers for steel sheets (Birmingham wire gage). The wall

thicknesses in standards for plastic tubing and some metal tubing do not cori

t
PIPE AND TUBING 111

TABLE 22. Wall Thicknesses of 6-Inch Pipe

Material Code Maximum

inch Nominalinch Minimuminch ASTM Standards

Iron

Steel Steel Aluminum

Plastic

Plastic

Steel, Aluminum.

Steel

Plastic

Plastic Cu, Ni

Iron Cu, Brass Cu-Ni

Cu, Cu-Si

Plastic Ni. Ti

Steel, Aluminum.

Plastic.

Steel...

Steel... Plastic.

Plastic.

Steel...

Steel... Ni, Ti..

Plastic

Steel, Aluminum.

Cu-Ni

Cu-Ni

Plastic Cu-Ni

Cu, Brass . Cu, Cu-Si

.

Steel

Steel

Plastic Steel

Plastic

Plastic Copper

Al, Ti

Ni. Cu-Ni.

Cu-Ni

Steel Al-Ti

Steel

Plastic Plastic

xxs

xxs

160 160 SDR I 120

120

SDR13.5

SDRI3.5

XS

xs

XS

xs

8080

80, XS

SDR 17

SDR 21

Class T

Std 40

40

40. Std

SDR 26

Regular

Regular

Regular

SDR32.5

SDR 41 TP

10

10

lOS

55SSDR 64

.675 .629

.550 .540

.494

.464

.472

.484

.486

.437

.354

.353

.315

.314

.277

.265 .286

.268 .264

.228

.182

.168

.151 .147 .139

.123

.124

.864

.719

.718

.603

.562 .562 .500

.491 .481 .457

.441 .437

.437

.437

.432

.432

.432

.390

.375 .344

,316

.315 .312 .286

.280

.280

.280

.259

.259

.255 .250

.250

.250 .250

.219 .204

.188 .180

.162

.158 .134

.134 .134

.134

.109

.109 .104

.100

.774

.756

.629

.628

.603 .562

.492

.438

.491 .481 .420

.386

.410

.402

.415 .432

.378

.378

.390

.328

.301 .316

.315

.273 .250

.245

.280

.245

.241 .253 .255 .232 .236

.238

.219 .192

.204

.165 .180

.162

.148

.117

.121 .129

.117

.095 .095 .104

.100

A72

A53, A 120, A524

A53, A524

B241, B345

D2446

D1785

A53, A524, B241, B345

A523

D2241, D2282, D2513

D2446

B466

A72

B42, B43

B466

B188, B135

D1527, D1785, D2447

B161, B165, B337

A53. A120, A312,

A524, B317. B241,

B345

D224I, D2282, D2446,

D2513

A523

A523

D2241, D2282, D2446,

D2513

D2241, D2282

A523

A72

B161, B165, B167,

B337, B407, B423,

B444, B445

D1503, DI527, D1785,

D2447

A53. A120, A3I2,

A523, A524, B317,

B241, B345

B466

B467

D2241. D2282, D2513

B466

842, B43

8188. 8315

A523

(ANSI 836.10)

D2241

(ANSI 836.10)

D2751

D2241

B302

B241. B345. 8337

8161, 8165, 8466

8467

A3 12 8241, 8345, B337

A312

D2241

D2729
112 ENGINEERING STANDARDS

respond to these gage numbers, but there does not appear to be a rational

basis for most of the values specified. For example, the ratio of outside

diameter to wall thickness should be constant for a particular pressure rating

and material. This ratio for copper tubing in water service ranges from 10.2

to 32.0 for Type K, from 12.5 to 43.7 for Type L, and from 20 to 50 for Type

M. Therefore, the pressure rating for a particular type varies with the diameter by a factor of about 3.

23.3 STANDARDIZATION NEEDS

The lack of agreement among domestic standards and between U.S. national standards and ISO Recommendations indicates the need for better

coordination of pipe and tubing standards, possibly assigning the responsibility for standardizing dimensions to a single U.S. Committee as in ISO.

Further, there has been a trend for some time away from threaded couplings

to other means for joining pipe and tubing, such as welding, soldering, ce- menting, and various types of connectors. Nonthreaded fastenings have per- mitted the use of pipe or tubing with thinner walls and hence they have con- served materials. As previously noted, standards for plastic pipe and tubing

have used the standard dimension ratio (SDR) or ratio of outside diameter to wall thickness as a more rational basis for selecting wall thicknesses of dif- ferent sizes of tubing. The use of SDR and preferred numbers could further

simplify the standardization of tubing dimensions and facilitate engineering

calculations since the internal cross-sectional areas of all tubing would be re- lated mathematically. Table 23 gives the outside diameters and wall

thicknesses in millimeters for various standard dimension ratios from 6.3 to 125. The RIO series of preferred numbers is used for the three quantities

(outside diameters, wall thickness, and SDR). Additional sizes for special

purposes could be added by the use of the R20 or R40 series and the table could be extended to higher or lower values for any quantity. However, the

28 sizes covering the range from 2 to 1000 mm outside diameter and the 14

wall thicknesses corresponding to the 14 values of SDR should suffice for nearly all tubing whether made from plastics or the strongest metal.

The pressure rating for tubing made from a particular material depends on

the allowable fiber stress and its SDR. Thus, in table 23. the pressure rating

is increased 25 percent in going from one SDR to the next lower SDR. For

a particular SDR, metal tubing having an allowable fiber stress of 110

MN/m- (about 16,000 psi) would have a pressure rating 10 times that of

plastic tubing having an allowable fiber stress of II MN/m- (about 1,600

psi). Conversely, tubing of this metal having an SDR of 100 would have the same pressure rating as tubing of this plastic having an SDR of 10; i.e., the

wall thickness of the plastic tubing would have to be 10 times that of the

metal for the same pressure rating.

There are of course limitations for thin tubing. The wall thickness must be

sufficient to provide the structural strength necessary for the application.

The maximum thickness is limited by the equipment used to fabricate the

tubing. For this reason, the thicknesses in table 23 have been arbitrarily
PIPE AND TUBING 113

TABLE 23. Illustrative Tubing Dimensions Based on Preferred

Numbers

[millimeters]

Wall thickness for standard dimension ratio ofeter 6.3 8 10* 12,5 16 20* 25 31.5 40* 50 63 80* 100 125

2.0 0.32

2.5 .40 0,32

3.2 .50 .40 0.32

4.0 .63 ,50 .40 0,32

5.0 .80 ,63 .50 ,40 0.32

6.3 1.00 .80 .63 ,50 .40 0.32

8.0 1.25 1.00 .80 ,63 .50 .40 0.32

1 0.0 1.60 1.25 1.00 ,80 .63 .50 .40 0.32

12.5 2.00 1.60 1.25 1,00 .80 .63 .50 .40 0.32

16.0 2.50 2.00 1.60 1,25 1.00 .80 .63 .50 .40 0.32 20.0 3,15 2.50 2.00 1.60 1.25 1.00 .80 ,63 .50 .40 0.32 25.0 4.00 3.15 2.50 2.00 1.60 1.25 1,00 ,80 .63 .50 ,40 0.32

31.5 5.00 4.00 3.15 2.50 2.00 1.60 1.25 1,00 .80 .63 ,50 .40 0.32 40.0 6.30 5.00 4.00 3.15 2.50 2.00 1.60 1,25 1.00 .80 .63 .50 .40 0.32

50.0 8.00 6.30 5.00 4.00 3.15 2.50 2.00 1.60 1.25 1.00 .80 .63 .50 .40 63.0 10.0 8.00 6.30 5.00 4.00 3.15 2.50 2.00 1.60 1.25 1.00 .80 ,63 ,50 80.0 12.5 10.0 8.00 6.30 5.00 4.00 3.15 2.50 2,00 1.60 1.25 1.00 ,80 ,63 100 16.0 12.5 10.0 8.00 6.30 5,00 4.00 3.15 2,50 2,00 1.60 1.25 1,00 ,80 125 20.0 16.0 12.5 10.0 8.00 6,30 5.00 4.00 3,15 2.50 2.00 1.60 1,25 1,00 160 25.0 20.0 16.0 12.5 10.0 8.00 6.30 5.00 4.00 3.15 2.50 2.00 1.60 1,25 200 31.5 25.0 20.0 16.0 12,5 10.0 8.00 6.30 5.00 4.00 3.15 2.50 2.00 1,60 250 40.0 31.5 25.0 20.0 16,0 12.5 10.0 8.00 6.30 5.00 4.00 3.15 2.50 2,00 315 50.0 40.0 31,5 25.0 20,0 16.0 12.5 10.0 8.00 6.30 5.00 4.00 3.15 2,50 400 63.0 50.0 40,0 31,5 25,0 20.0 16.0 12.5 10.0 8.00 6.30 5.00 4.00 3.15 500 63.0 50,0 40.0 31,5 25.0 20.0 16.0 12.5 10.0 8.00 6.30 5.00 4.00 630 63,0 50,0 40,0 31.5 25.0 20.0 16.0 12.5 10.0 8.00 6,30 5.00 800 63,0 50,0 40.0 31.5 25.0 20.0 16.0 12.5 10.0 8,00 6.30 1000 63,0 50.0 40.0 31.5 25.0 20.0 16.0 12.5 10.0 8.00

'Internal diameters are preferred numbers in RIO, R20. R40 and R80 series, respectively.

restricted to the range of 0.32 to 63 mm. This range could be made larger or

smaller as required.

In order to facilitate compatibility between tubing and fittings, it is desira- ble that standards for tubing have only minus tolerances and standards for

fittings have only plus tolerances. The use of preferred numbers for tolerances is advantageous for either a decreasing percentage with increasing values or a constant percentage. Table 24 illustrates both cases. For outside diameters in the RIO series of preferred numbers, tolerances are given

in the R20 series for three cases designated small, medium, and large in the

proportion of 1:4:16, respectively. This proportion could be changed and

starting values for the small tolerance could be shifted up or down. The important feature is that the tolerance increases in a rational manner tenfold for an increase of hundredfold in outside diameter. A single set of tolerances

would be chosen for any one type of tubing.

For illustrative purposes, the RIO series of preferred numbers is chosen

for both wall thicknesses and their tolerances in table 24. Thus, the tolerance

is a fixed percentage of the wall thickness; small, medium, and large values

are selected to be 5, 10, and 20 percent, respecfively. These values are in-
114 ENGINEERING STANDARDS

TABLE 24. Illustrative Tolerances on Tubing Dimensions

[millimeters]

Outside

diameter

Tolerance* Wall

Thickness

Tolerance**

Small Medium Large Small Medium Large

2.0 0.016 0.063 0.250 0.32 0.016 0.032 0.063

2.5 .018 .071 .280 .40 .020 .040 .080

3.2 .020 .080 .315 .50 .025 .050 .100

4.0 .022 .090 .355 .63 .032 .063 .125

5.0 .025 .100 .400 .80 .040 .080 .160

6.3 .028 .112 .450 1.00 .050 .100 .200

8.0 .032 .125 .500 1.25 .063 .125 .250

10.0 .036 .140 .560 1.60 .080 .160 .315

12.5 .040 .160 .630 2.00 .100 .200 .400

16.0 .045 .180 .710 2.50 .125 .250 .500 20.0 .050 .200 .800 3.15 .160 .315 .630

25.0 .056 .224 .900 4.00 .200 .400 .800

31.5 .063 .250 1.00 5.00 .250 .500 1.00 40.0 .071 .280 1.12 6.30 .315 .630 1.25 50.0 .080 .315 1.25 8.00 .400 .800 1.60 63.0 .090 .355 1.40 10.0 .500 1.00 2.00

80.0 .100 .400 1.60 12.5 .630 1.25 2.50 100 1 1

.112 .450 1 .oU 16.0 .oUU 1 .dU 3.15 125 .125 .500 2.00 20.0 1.00 2.00 4.00

1 AO .140 .560 2.24 1.25 2.50 5.00 200 .160 .630 2.50 31.5 1.60 3.15 6.30 250 .180 .710 2.80 40.0 2.00 4.00 8.00 315 .200 .800 3.15 50.0 2.50 5.00 10.00 400 .224 .900 3.55 63.0 3.15 6.30 12.5 500 .250 1.00 4.00 630 .280 1.12 4.50 800 .315 1.25 5.00 1000 .355 1.40 5.60

'Tolerances are all minus; plus tolerance is zero. R20 series of preferred numbers is used for tolerances on outside diameters

of the RIO series. Small, medium and large are in the proportion I ;4;]6. Other proportions could be used or values for toler- ances could be shifted up to down as required.

* 'Tolerances are all plus; minus tolerance is zero. RIO series of preferred numbers is used for both tolerances and outside diameters. Therefore, tolerances are constant percentages of diameters. Small, medium and large are 5,10, and 20 percent, re- spectively. Other percentages could be used.

dicated to be plus tolerances to assure adequate strength of the tubing. The

percentages in table 24 are arbitrarily chosen. For a particular type of tubing, a single percentage from the RIO series of perferred numbers would be

chosen.

Although the use of preferred numbers could be used for dimensions and

tolerances of tubing based on the inch unit, the greatest advantage would be

achieved by using SI units and international standardization. Present outside

diameters of pipe used in threaded applications would probably not be

changed in view of their standardization internationally for most sizes. However, wall thicknesses and tolerances could be based on preferred numbers

and standardized internationally.
24. SCREW THREADS AND FASTENERS

24.1 BACKGROUND

The first known practical application of the screw was developed by

Archimedes over 2,000 years ago, but the screw did not become important

in commerce until the industrial revolution. The most important part of a screw is the thread. A screw thread is a ridge in the form of a helix on the external or internal surface of a cylinder or cone. It is essentially a spiral

inclined plane or wedge whose mechanical advantage is used to increase the

applied force. Screw threads serve many functions such as connectors or

couplings, fasteners, gas and liquid seals and translators of motion or power.

Thus, they are important elements of the nation's technology. Most screw

threads are used for fastening. In a real sense, they are the "nails" of the

metal age. Although adhesive bonding and welding are increasingly used in permanent fastening, threaded fasteners are unmatched in coupling and

fastening parts that require future disassembly.

The screw is one of six simple machines; the others being the lever and

fulcrum, wheel and axle, pulley, inclined plane, and wedge. Of these, the screw is the most complex and difficult to standardize dimensionally in order

to achieve interchangeability. The standardization problem stems from the numerous forms or shapes of screw threads in use. The Robertson Guide to World Screw Thread Series Symbols, issued by W. H. A. Robertson and

Company, Ltd., Bedford, England in 1962, lists 180 thread forms or shapes.

Most of them are modifications of the 55 degree V-thread proposed in 1841

by Sir Joseph Whitworth in England and the 60 degree V-thread proposed

by Mr. William Sellers of the Franklin Institute, Philadelphia in 1864.

The Whitworth thread was adopted as a British Standard in 1905 and its use became widespread in countries that adopted British technology. The

115
116 ENGINEERING STANDARDS

Sellers thread was adopted by many industries in the United States, but it had not been standardized nationally when World War I started. The need

for interchangeability of parts in the mass production of war material led to passage of Public Law No. 201 in July 1918 creating a commission for the

standardization of screw threads. The National Screw Thread Commission

consisted of representatives from the Commerce, Navy and War Departments, the Society of Automotive Engineers, and the American Society of

Mechanical Engineers. The Director of the National Bureau of Sandards

served as Chairman. Congress underestimated the Commission's task since

its tenure was authorized initially for 6 months. After four short extensions,

the time limit was dropped. The Commission issued reports in 1921, 1925,

1929, and 1933 (NBS Miscellaneous Publications 42, 61, 89, and 141,

respectively). The Commission was abolished by Executive Order in March

1933 as part of an economy reorganization during the depression. The Commission Reports included standards for the American National threads

based on the Sellers thread form. Acme threads, hose threads, threads for

electric lamps and sockets, and threads for wood screws. They also included

methods for gaging threads.

The threat of World War II led the Secretary of Commerce to establish

with the Secretaries of War and Navy the Interdepartmental Screw Thread

Committee in 1939. This Committee issued NBS Handbook H25, Screw

Thread for Federal Services in 1939. It was revised in 1942 and issued as NBS Handbook H28. New editions or supplements of NBS Handbook H28

were issued in 1944, 1950, 1957, 1963 and 1969. Although the screw thread

standards in NBS Handbook H28 are mandatory only for Federal Agencies,

they have in fact become national standards since ANS Bl.l and B1.2 is- sued by the American National Standards Institute are identical with cor- responding standards in Handbook H28.

24.2 INTERNATIONAL STANDARDIZATION

The use of different national standards by the Allied Nations during World

War II, particularly the Whitworth thread in the United Kingdom and the

American National thread in the United States led to a series of conferences

after the War which were attended by representatives of Canada, United

Kingdom and United States. These conferences resulted in the Declaration

of Accord on November 18, 1948 establishing the standards for the Unified

Screw Threads. These standards were based on those for American National Threads. The basic profile of the Unified Thread was adopted by ISO

for both metric and inch general purpose screw threads. The Unified (ISO)

and the American National Thread forms are illustrated in figure 5. The first technical committee established by ISO was on screw threads.

This committee has developed through 1969 the nine ISO recommendations

on screw threads listed in table 25. ISO Recommendation R68 gives the

basic profile. The inch screw threads in ISO Recommendations R263 and

R725 are the Unified Threads. The other six recommendations pertain to
SCREW THREADS AND FASTENERS 117

hX|<D

I

j \ 1 V

H

/ i

1

a. a| (D

1 r

>

o < 1

\

Pilch

diameter

Minor dionneter

rit*

X

I 1 -—«*» —

K , !

t ||

o!

4 1

1

o. a|ao

t HP t

1

L

m

f; •

e

0. .5

•o

CO

re 4J

<u x:

l-l bL a: •H CO H <U x:

II ( tH re (1) •H 4J c t—

I

M-i o bC

tfl o bQ •H C

(U >-l •H re

l-l & OJ re J= l-l H 1-1 4-1 re XI c

iH o re re

re f-( V re c M l-l •H 4.1 o l-l c

•H a) 4J Q) u 1 J E

to B 01 < re >> 0)

CO •H c c l-l C 3

to CO OJ re <4-l o l-l CO •H <u y—

CO

l-l t-H -C •u 0)

i-l o (U •H J

(U c •H U-i < CO •H •H

VI C

c (jC •H

>—

CO o 3:

l-l •oc

re

COe X. 00 l-l o

o 4J

l)-l •H o in a

•H o X)

CO •H II re CO

re Q) (U 4J l-l H

(U x: X. Uh o e oc u •H

•H c

l-l OJ o tic c 4= •H •H -a re CO CO

re •a re x; re pq u o 0)

l-l H x:u iri T3 Q)

<U r-l CO (U •H -H <U U

i*-l -H 3

•H O iJ 60 C l-l U iH
118 ENGINEERING STANDARDS

metric screw threads. These metric threads are being adopted as national

standards by most countries and are tending to replace the inch threads and

over 20 different metric thread systems used in these countries.

TABLE 25. International Standards for Screw Threads and

Fasteners

ICO I 1 c U.S. 1U1 1/

. K.. France Germany Italy Japan India Rec. (ANSI) (BS) (AFNOR) (DIN) (UNI) (JIS) (IS)

Screw

Threads: 68 Bl.l, (-) E03-001 13/30 *4533 () *1330, 1362

1.10 261 Bl.lO *3643 E03-013 13/12 M534-5 *4218

262 *3643 E03-014 n3/33 *4536 (") *4218

263 *B1.1 *1580 (10, 724 *3643 E03-052 *13/1 *5535 *4218

725 *B1.1 *1580

965/1 ... E03-051 *13/32 *5541-2 *4218

965/H... E03-053 *5546 *4218

965/III.. *4218

Fasteners: 225 *5624 *1367

iji (•) (4)* *E27-31

*5625-7 ('-) *1363-4, 2389

273/1 *4186 E27-040 *69 1728 BIOOI *1821

273/11... E27-040 *69 BlOOl *1821

288/1 *3692 E27-414 *935 *5593-5 Bl 170 *2232

288/11... E27-414 *935 Bl 170 733 {') E27-024 *475/l

861 *9I2 *5931-2 Bl 176 *2269

885 E.27-028 *267 (13, *4172

887 *125, 126 B1256 *2016

888 E27-025 C) *5626 (14, *4206

898/1 *267/3 *1367

898/11... *E27-005 *267/4 M367

898/III.. *E27-005 *267/7, 8 *1367

' ANS B18.2.1. 18.2. :, 18.6.3.

- BS 1580, 3369, 3643.

' BS 3692, 4168, 4183, 4190.

^ BS 3692, 4190.

5 DIN 555, 558, 601, 931, 934, 960. 961. «D1N 558,601,603-8,912,931,960,6912, 7984. 'JIS B0205, 0206, 0207, 0208. "JIS B0205, 0207. "JIS B0205. 0207, 1 180, 1 181.

I" JIS B0206, 0208. "JIS BllOl, 1173, 1180.

'^JIS BI002, 1 180, 1 181 ''JIS Bl 101, 1 180. '^JIS Bl 101, 1 1 1 I, 1 173, 1 176, 1 179. 1 180, 1 182. 'Essentially in agreement with ISO Recommendation; agreement with Japanese (JIS) standards was not determined.
SCREW THREADS AND FASTENERS 119

24.3 DYNAMICS OF SCREW THREAD

TECHNOLOGY

The 1 80 thread forms currently used throughout the world and the activity

within ISO indicate two opposing movements; one tends to proUferate the

sizes and shapes of threaded forms, and the other is directed toward stan- dardization and reduction in thread sizes and shapes. These two movements

are occurring simultaneously. Standardization of screw thread dimensions

nationally and internationally fosters efficiency and economy in production.

On the other hand, rigid adherence to an existing thread system or an overly

conservative acceptance policy for new thread systems, interferes with the

application of new technology and hinders development of new markets. A

balance of the two movements is essential for a healthy and vigorous econo- my.

For a particular application, the thread may be any one of innumerable

combinations of diameter, pitch and profile. The particular design used may

be chosen for economic reasons, to stifle competition, to gain proprietary advantage, or to be consistent with customary units of measurement and en- gineering standards of related products. Whatever the motivation, this freedom in design provides the innovations and new concepts in thread

technology. However, without restraint it results in chaos and the advantages of interchangeability and mass production are lost. Innumerable

bolts, nuts, taps, dyes, and gages have to be produced and kept in inventory

with an attendant increase in cost. In addition to the economy of mass production, standardization is fostered

by the reduction in engineering data that must be generated regarding

strength, fatigue life, tolerances, etc. and in the number of gages and gaging

practices that must be developed. Currently, the movement toward standardization of screw threads tends to be predominant and opportunities for

introducing new thread series are becoming less frequent, particularly when

it is to replace a screw thread series that has been standardized and widely

accepted internationally.

The Industrial Fasteners Institute recognizes that innovation in screw

thread design is becoming more difficult, and that a change from inch-base to metric-base fasteners may provide a rare opportunity for improving screw

thread and fastener technology. The Institute is sponsoring the development

of an optimum fastener system based on current knowledge and technology.

(See sec. 24.15.)

24.4 SPECIFICATIONS FOR SCREW THREADS AND

FASTENERS

The complexity of the thread is responsible for separate standards for the screw thread and for the fastener exclusive of the thread. This complexity can be seen by the following comparison of requirements that must be

specified in the two cases:
120 ENGINEERING STANDARDS

Screw thread Threaded fastener Major diameter

Pitch diameter Minor diameter

Direction of thread Included angle of thread Leading flank angle of thread Following flank angle of thread Lead or helix angle of thread Thread ridge thickness Thread groove thickness Fundamental triangle height

Thread series Thread sizes Overall length

Threaded length

Nonthreaded diameter Head shape or type Dimensions of head

Material Working strength Surface coating or treatment Radius at head-body junction Crest truncation and contour Number of incomplete threads at start Root truncation and contour Tolerances for class of fit Taper of thread Depth of thread engagement

Length of thread engagement

Method of gaging

The numerous parameters listed above that can be varied in a screw

thread make the clearances and tolerances critical in order to have in- terchangeability. Three classes of fit are provided in the Unified Thread Series designated 1 A. 2 A. and 3 A for external threads and IB, 2B, and 38 for

internal threads. ISO Recommendation R965/I prescribes a more elaborate

system of tolerances. For an external thread, seven tolerance grades and

three tolerance positions are permitted for pitch diameter, and three

tolerance grades and three tolerance positions are permitted for major

diameter. For an internal thread, five tolerance grades and two tolerance

positions are permitted for both pitch and minor diameters. Among the 189

possible tolerance combinations classes for external threads, only 13 tolerance classes are recommended. Similarly, among the 100 possible combinations for internal threads, 13 tolerances classes are recommended.

Nevertheless, the 13 recommended ISO tolerance classes apparently are many more than necessary since three classes suffice for Unified Threads.

The designation of the ISO metric thread is also more complex. For example, the thread of a fine 6 mm diameter, 0.75 mm pitch bolt and nut with

minimum tolerances might be designated: 1VI6 x 0.75 — 4H/3h4h for the ISO

metric thread. The corresponding Unified extra fine thread for a 0.25-inch

diameter, 32 threads per inch bolt and nut is designated: 1/4 — 32

UNEF-3A/3B.

Table 25 lists the 23 ISO Recommendations issued through 1969 by TC

1 on Screw Threads and TC 2 on Bolts, Nuts and Accessories together with

corresponding American (ANSI), British (BS), French (AFNOR), German

(DIN), Italian (UNI), Japanese (JIS), and Indian (IS) national standards.

U.S. approved 13, disapproved six and did not vote on four. These recommendations pertain to metric threads and fasteners except for ISO Recommendation R263 and R725 which pertain to the Unified inch thread and R68

which gives the basic profile for both metric and inch threads.
SCREW THREADS AND FASTENERS 121

24.5 GAGING PRACTICES

Section 6 of NBS Handbook H28 deals with Gages and Gaging for

Unified Screw Threads. It is the largest and one of the most important sections in these screw-thread standards. The numerous parameters in a standard screw-thread makes the development of gaging practice difficult. On

the one hand, the practice must assure interchangeability and compliance

with the standard. On the other hand, the practice must be suitable for in- spection of the tremendous production of threaded fasteners which has a value of nearly 2 billion dollars per year. The diverse national practices have made international standardization of

gaging practices more difficult than standardization of profile and sizes of screw threads. In the development of the Unified Screw Thread in 1948, the

difference in gaging practice used in the United Kingdom and the United

States was not resolved and each country continues to use its own practice.

As a result, a borderline screw thread might be placed in different classes of

fit in the two countries.

The objective of a gaging practice is to accept all screw threads within

tolerance limits and to reject all threads outside those limits. Measuring

methods are practices directed toward determining actual magnitude of in- dividual dimensions of the thread; whereas, gaging utilizes functional

processes that test whether the resultant of all errors in the thread elements

provide a thread form within material tolerances. In measurement of pitch diameter, U.S. practice differs from that in other

countries in two respects: (1) In the U.S., measurements are made only on

external threads; internal threads are judged on the basis of fit to the measured external threads. (2) The U.S. does not follow the practice of the countries that apply corrections to pitch diameter measurement for deformations,

resulting from the measurement process and corrections for lead angle contribution. The U.S. chooses to follow a simplified practice, accepting a small

inaccuracy that does not exceed 8 percent of the most critical tolerances for

pitch diameter of standard threads.

ISO Recommendafion on gaging issued in 1970 follows closely the British

gaging practice. The following differences exist between U.S. and British

gaging practices:

(1) The U.S. utilizes adjustable split ring gages in testing external threads.

British Standard specifies solid ring gages which requires many more plug

gages to monitor the ring gages. Wear on the solid ring gages results in a very

limited service life. (2) The British "not go" plug gage has a greater truncafion of thread crest than the U.S. gage, since the British believe that greater truncation provides a more critical test for detecting defective thread form. U.S. practice allows

for greater entry than the British practice in "not go" gaging tests.

(3) U.S. tolerances for external thread (ring) gages are slightly more strin- gent than British tolerances. On the other hand, U.S. tolerances for internal

thread (plug) gages are considerably more liberal than the British tolerances.

Both British and U.S. tolerances for ring and plug gages allow departures
122 ENGINEERING STANDARDS

greater than the tolerance allowed for pitch diameter of class 3 thread

products.

In general the U.S. philosophy in standards favors simplified gaging and

measurement procedures to serve the needs of mass production. U.S. practice uses fewer gages, less complicated mathematics and measurement practices, and less sophisticated measuring equipment. This simplification sacri- fices some accuracy in determining actual size of screw thread and generates

the basic disagreement between U.S. and British practice. British measure- ment practices are accurate to about l.S/xm (0.00005 in) as compared to about 3.8/u,m (0.00015 in) in U.S. practice.

24.6 THREAD FORM

The form or profile of screw threads is as critical to compatibility as dimensions of thread elements. Since threads can be scaled up or down in size without change in profile, incompatibility in thread form is not caused

by basing design on different measurement units. Specificafions for the fol- lowing thread forms have been or are being developed by ISO or lEC:

(1 ) Unified Form — an equilateral triangular form of thread (apex angle 60

degrees) truncated at crest and root. The root is generally rounded and the

crest is sometimes also rounded. This form is used for general purpose

threads, both inch and metric and is the most extensively used of all forms.

The miniature thread and the rounded root (UNJ) threads have a modified

Unified thread form in which the root of external thread is more rounded and

the thread is smaller in height. The largest use is m fasteners such as bolts,

nuts, screws, and tapped holes.

(2) Whitworth Form — a triangular form of thread with a 55 degree apex

angle, rounded at crest and root. This form is used in tapered and straight

pipe threads except in the U.S. Its principal application is in threaded pipe

couplings, fittings, valves, and similar pressure tight connections.

(3) Trapezoidal Form — an extensively truncated triangular form of thread

with a 30 degree apex angle. In the U.S., a 29 degree apex angle is used. This

form is used primarily for traversing components of machines and mechanical tools. (4) Edison Form — a thread form composed of two circular segments tan- gent to each other and of equal radii. This form is used for electric lamp

screw bases and sockets.

(5) Glass Form — a special thread form for glass containers having screw

closures based on British Standard 1918.

Thusfar, ISO has not undertaken standardization of threads for aircraft fasteners, microscopes, and photographic equipment, and of Acme and Buttress threads. U.S. standards for the following threads are not compatible in shape with comparable international standards: pipe threads, gas cylinder

valve outlet and inlet threads, and hose coupling threads.
SCREW THREADS AND FASTENERS 123

24.7 COMPARISON OF THREADS OF UNIFIED

FORM

Different forms of root truncation and rounding have attracted sufficient

proponents so that three forms of Unified Thread with different roots now

exist. For automotive and most industrial fasteners, the thread form in ISO

Recommendation R68 is being accepted. The aerospace industries favor a more truncated (reduced thread height) and controlled root radius of external thread designated as the UNJ thread form (Mil Std 8879), which is not interchangeable with the UN form. The miniature screw thread has a form

intermediate between the UN and UNJ forms. The ISO metric thread and

the Unified inch thread have the same form. The two thread systems differ only in choice of diameters and pitch lengths for standard sizes. Thus, it is possible for metric and inch threads to be compatible if the tolerances for the

two threads overlap. To be compatible, the pitch and pitch diameter of both

external and internal threads must meet requirements given in appendix IV. A comparison of pitch lengths for both Unified inch and ISO metric screw

threads indicates that the following seven combinations are the only ones

potentially compatible:

Threadslinch mm

72 0.35 64 0.4 56 0.45 44 0.6 36 0.7 32 0.8 20 1.25 A comparison of pitch diameters for these pitch lengths indicates the fol- lowing six combinations are potentially compatible:

Unified Thread* Metric Thread**

UNF 0.73 -72 M 1.8 x 0.35 UNF .086 -56 M 2.2 x 0.45 UNF .099 -56 M 2.5 x 0.45 UNF .164 -36 M 4.0 x 0.7 UNF .190 -32 M 5.0 x 0.8 UN .3125-20 M 8.0 x 1.25 *UNF signifies Unified fine thread, the first number

indicates major diameter in inch unit, and the second number

indicates the number of threads per inch. **M signifies metric, the first number indicates major

diameter in millimeters and the second number indicates

the pitch (distance between thread centers) in millimeters.

Assuming a Class 2 tolerance for the Unified Thread and an ISO grade 6

tolerance for the metric thread, the first three combinations are compatible

if manufacturing tolerances be asymmetric to the basic pitch diameter and

limited to approximately 50 percent of the magnitude of Class 2 tolerances

for pitch diameter. The fourth and fifth combinations are compatible only near the tolerance limits, and the last one is not compatible within Class 2 tolerances and allowances.

422-764 OL - 71 - 9
124 ENGINEERING STANDARDS

While it is not recommended to combine a metric and inch thread, the

combinations noted above show that the ISO metric and Unified threads are very similar. Either series could satisfy the needs of a general purpose screw

thread system for most fastener applications.

There are 319 thread sizes listed in the U.S. standards for Unified

Threads covering a range in diameters from 0.06 in (1.5 mm) to 6 in (152

mm) and pitches from 80 to 4 threads per inch, (0.3175 to 6.35 mm pitch).

Each thread size is manufactured in at least two classes of fit. The metric series of general purpose screw threads includes 332 thread sizes covering a range from 1 to 300 mm in diameter and 0.2 to 6 mm in pitch. Each size may

be manufactured in a number of tolerance grades. Thus, the U.S. faces the

prospect of doubling the number of thread sizes if the current trend to use both inch and metric thread sizes expands. Such a course is inefficient and

costly. The trend should be in the opposite direction; that is, the number of

thread sizes should be reduced to promote efficiency and economy.

24.8 MINIATURE SCREW THREADS

Screw thread diameters below 0.06 in (1.5 mm) have a Unified form with

a more truncated root. The U.S. standards for these threads are based on

metric dimensions so that measurement units are not responsible for any in- compatibility. The proposed ISO Recommendation differs from the U.S.

Standards with respect to tolerances. For external threads, the U.S. standards are more stringent; whereas, for internal threads, the proposed ISO

Recommendation is more stringent.

There are 14 thread sizes in the miniature thread series listed in NBS

Handbook H28. They are all inherently compatible with those in the

proposed ISO Recommendation. The differences in tolerances between

U.S. and ISO specifications are annoying in manufacture and may cause

confusion. A manufacturer making miniature screw threads for international commerce must adhere to smaller tolerances than one manufacturing for domestic trade only.

24.9 EDISON SCREW THREADS

There are five sizes of thread used for electric lamp bases and sockets.

They are designated Miniature, Candelabra, Intermediate, Medium and

Mogul. The dimensions of these threads in NBS Handbook H28 are similar

in form and essentially identical in pitch to corresponding threads in lEC

Recommendation No. 61-1. However, there are significant differences in major and minor diameters of the threads specified in the two documents;

mainly, (1) The U.S. Intermediate Thread is not interchangeable with the

lEC thread, (2) Lamps with lEC E27 threads, will fit U.S. Medium lamps

sockets, but not all lamps with U.S. Medium threads fit lEC E27 sockets,

and (3) Lamps with lEC E40 threads fit U.S. Mogul lamp sockets, but lamps

with U.S. Mogul lamp threads do not fit lEC E40 sockets since the minor
SCREW THREADS AND FASTENERS 125

diameter of U.S. threads is too large to be interchangeable. The U.S. and

lEC threads are not identical in shape, since the radii specified for the rolled threads generally differ.

24.10 PIPE THREADS

NBS Handbook H28 Part II, gives specifications for the following pipe

threads:

NPI — American Standard taper pipe threads for general use NPSC — American Standard straight pipe threads in pipe couplings

NPTR— American Standard taper pipe threads in railing joints

NPSM — American Standard straight pipe threads for free-fitting

mechanical joints for fixtures

NPSL — American Standard straight pipe threads for loose-fitUng

mechanical joints with locknuts.

NPTF — Dryseal American Standard taper pipe thread

PTF-SAE SHORT- Dryseal SAE short taper pipe thread

NPSF — Dryseal American Standard fuel internal straight pipe thread

NPSI — Dryseal American Standard intermediate internal straight pipe

thread

UNS — Threads for use on thin-wall tubing, 27 threads per inch.

NGT — National gas taper threads

SGT — Special gas taper threads

NGS — National gas straight threads

NGO— National gas cylinder valve outlet threads

NPSH — American National hose coupling threads

NH — American National fire-hose coupling threads — American National hose connections for welding and cutting

equipment.

In addition to the pipe threads listed in NBS Handbook H28, there are

several standards issued by the American Petroleum Institute giving specifications for pipe threads used in the oil industry. These standards include 12

thread forms which have tapers of 1:4, 1:6, 1:16, 1:32 and straight. These

pipe threads are used throughout the world in the oil industry. However,

they have not been adopted by either ANSI or ISO.

All U.S. pipe and hose threads have an equilateral triangular form, differ- ing from the Unified Thread form generally in a smaller extent of truncation.

Pipe threads also differ in pitch and diameter from the Unified inch and ISO

metric thread sizes and most are tapered.

Since the pipe threads in NBS Handbook H28 have an apex angle of 60

degrees, they are not compatible with those in ISO Recommendations R 7 and R 228 which are based on the Whitworth form having an apex angle of

55 degrees. On the other hand, the outside diameters of most sizes of U.S.

and ISO pipe are the same. Hence the incompatibility results from dif- ferences in thread design and not from measurement units. Because of the in- compatibility in thread forms, couplings, fittings and valves are also incom-
126 ENGINEERING STANDARDS

patible. It should be noted that the incompatibility between U.S. and ISO

pipe threads does not result from the use of metric dimensions, but is in- herited from past incompatibility of British and U.S. Standards for pipe

threads.

For threads used in hose couplings and connections to gas cylinders, there

is no ISO Recommendation at present. If ISO chooses to base a future

recommendation for thread used in these applications on the Whitworth

form, they will be incompatible with U.S. Standards also because of design.

American Standard taper pipe threads are used in Canada and Venezuela,

but the ISO pipe thread is used throughout the rest of the world. New

technology with more efficient and economic design for joining pipe and

fittings is probably required to achieve world wide standardization.

24J 1 TRAPEZOIDAL SCREW THREADS

The trapezoidal form of thread used in the U.S. has a thread height equal

to one-half of the pitch and is known as an Acme thread. It is used extensively in machines and mechanical tools to convert rotary into linear motion or

to transmit power. The apex angle of the thread is 29 degrees. Currently,

there is no ISO Recommendation, but a proposed Draft Recommendation

is sufficiently developed to indicate that an angle of 30 degrees will be

specified. If so, the Acme and ISO trapezoidal threads will not be compatible. ISO is also considering a proposal for the Acme thread. The U.S. is not represented on the ISO Working Group for Trapezoidal Screw Threads so

that the U.S. Standards may not receive adequate consideration. There are also U.S. standards for trapezoidal threads having smaller thread heights

than the Acme thread; namely, 0.375, 0.3 and 0.25 of the pitch value. They

are known as Stub Acme Threads and are used where the Acme threads are not suitable. There is currently no comparable ISO Recommendation, but

the ISO Working Group for Trapezoidal Screw Threads has been requested

to develop a proposed specification for them.

24.12 BUTTRESS THREAD

This thread is used in application where high stresses are involved in a

direction along the thread axis. The pressure flank is nearly perpendicular to the thread axis so as to reduce radial components of thrust to a minimum.

Typical applications are the breach mechanisms of large guns and airplane

propeller hubs. NBS Handbook H28 specifies a pressure flank of 7 degrees

from the normal to the thread axis and a clearance flank of 45 degrees. The

thread height is 0.6 of the pitch value. Several other national standards exist,

but there has been no attempt toward international standardization.
SCREW THREADS AND FASTENERS 127

24.13 THREADS FOR MICROSCOPES

NBS Handbook H28 specifies a truncated Whitworth thread form with

apex angle of 55 degrees for microscope objective and nosepiece threads.

The major diameter is 0.8 inch and there are 36 threads per inch. This thread

is completely interchangeable with the RMS thread developed by the Royal

Microscopical Society of Great Britain and is almost universally accepted.

However, it lacks formal recognition as an international standard.

24.14 OTHER THREADS

NBS Handbook H28 describes several threads for the following special

applications:

American tripod to American camera fastener

American tripod to European camera fastener

Attachment of mounted lenses to photographic equipment

Attachment of lens accessories to lens mount

Attachment of shutter cable release to American camera

Attachment of shutter cable release to European camera

Dairy sanitary fittings

Glass containers

Plastic containers

Metal containers

Modified square thread for machines

60 degree Stub thread for machines

Most of these threads are not compatible with other national standards

and an ISO Recommendation has been issued only for the threads used in screw closures on glass containers. British Standard 1918 is used in the U.S.

for these screw threads and is the basis for ISO Recommendation Rl 1 15. However, BS 1918 and ISO/Rl 115 are not compatible in all specification

requirements, but BS 1918 is likely to be revised to conform with

ISO/Rl 1 15. Some of the threads for these special applications are used to some extent in other countries. In fact, some are used specifically as inter- face adapters between American and European products. Such adapters are one means of resolving the incompatibility between U.S. practices and those

in other countries. However, international standardization is a preferable

solution.

24.15 FUTURE TRENDS

The current trend toward increasing use of metric fasteners in the U.S.

doubles the number of sizes that must be manufactured and inventoried.

This evolutionary process of metrication can double inventory costs without

compensating benefits and can place the U.S. at an economic disadvantage

compared to a country using metric fasteners practically exclusively. In ad-
128 ENGINEERING STANDARDS

dition, the continued use of two series causes confusion and error in the

replacement market indefinitely. Individual manufacturers are free to use only one series, but the consumer is burdened with the costs and disadvantages of maintaining a dual system.

Recognizing the current trend, the Industrial Fasteners Institute has un- dertaken a study to develop an optimum metric fastener system. The first progress report on this study is given in appendix V. The study shows how

the adverse impact of metrication can be minimized and the benefits maximized. Instead of adding 57 ISO metric sizes to the existing 59 inch sizes of screw threads, the study proposes a new series of only 25 sizes to replace

both. The new series is based on the UNJ thread form used for aircraft which has been found to have superior fatigue resistance. The sizes from 1 to 25 mm in diameter are rationalized by means of the RIO series of

preferred numbers. Thus, a metrication program could provide the rare opportunity and incentive for changing screw thread standards taking advantage of current knowledge and technology. Such a drastic change in standards is possible with inch screw threads, but it is not likely since the incentive for change does not exist. Metrication requires change. In any metrication program, advantage can and should be taken of such a change to simplify and improve engineering standards, not only for screw threads and

fasteners, but for all industrial products conforming to national standards.
25. DISCUSSION

It is apparent from this study that a large proportion of engineering standards either do not have measurement units or use such units only as a lan- guage. This fact attests to the separate identities and purposes of standards

and units. Yet in the domain of dimensional specifications, the two are so

intimately intertwined through custom that the compatibility of these standards is related to the units. However, compatibility does not depend on the

units alone. For all standards including dimensional specifications, the entire engineering practice must be the same to achieve compatibility. Thus,

dimensional specifications in both metric and nonmetric countries are compatible if the engineering practice is the same, even though one expresses

dimensions in millimeters and the other in inches. On the other hand,

corresponding dimensional specifications expressed in the same unit are incompatible if the engineering practices differ. Apart from the role of units in dimensional specifications, the use of

the same units in all engineering standards facilitates communication. The

traditional use in the U.S. of metric units in biological and chemical standards reflects their worldwide use in these sciences for communication

purposes. The International System of Units' (SI) adopted by the General

Conference on Weights and Measures simplifies the measurement units

and communication. The current trend throughout the world, including

the U.S., is to include or use SI units in engineering standards. ISO, ASTM,

and other organizations now require the inclusion of SI units in addition to or in place of customary metric or inch-pound units. As these units become

incorporated into more and more standards, resistance to standards which

do not use them is likely to grow in international forums.

The findings of this study indicate that the inclusion of SI units into

U.S. standards is not sufficient to promote their use internationally. The

standards must be drafted in such form that they can be used easily in both

metric and nonmetric countries. For example, the standards should permit

129
130 ENGINEERING STANDARDS

tests to be made with equipment graduated in either U.S. customary or

SI units and with specimens having either customary inch or metric dimensions. Standards drafted in this way standardize the essential features of

engineering practices without restricting their use by nonessential

provisions.

In addition to the inclusion of SI units and the drafting of U.S. standards

to permit their use easily in other countries, participation in international

forums on standardization is necessary to promote them. The study indi- cates that currently the U.S. participates in less than 50 percent of the

working groups which draft the proposals for lEC and ISO Recommendations. Even the current level of participation is primarily the result of a growing awareness during the past 10 years of the need for participation. In many instances, U.S. participation starts after the issuance of several

recommendations which are not in accord with U.S. engineering practices.

By this time, other recommendations have been drafted and well on their way to approval. It is only on recommendations issued some 3 or more

years after participation begins that U.S. representatives can be effective

in having U.S. practices considered. In view of the increasing rate at which

I EC and ISO Recommendations are being issued, immediate steps need

to be taken for U.S. participation in the other working groups if U.S.

engineering practices are to be considered in drafting the I EC and ISO

Recommendations still needed for international trade. Although only

10 percent of the necessary 15 to 20 thousand lEC and ISO Recommendations have been issued, it appears from current interest in international

standardization that most of the remainder will be drafted during the next 10 years and issued within 15 years. Thus, the next 10 years are criti- cal, and provide a last chance for U.S. participation to be effective. The cost of full participation is substantial. Travel costs for delegates

alone may be nearly two million dollars per year. The salaries of delegates

and others for their time devoted to international standardization can not be easily estimated, but these costs may be 10 or more times the travel

costs. In addition, consideration needs to be given to the administrative

organization and cost for processing the increasing number of standards at both the domestic and international levels. The diversity of standards making activities may in some respects within the U.S. be desirable, but it is not conducive to effective U.S. representation in international forums. The

organization representing the U.S. in lEC, ISO and other international

standardizing activities would be more effective if it embraced the entire

repertoire of standards and assured adequate representation of the interests

of consumers, producers and government.

The current worldwide interest in international standardization and

harmonization of national standards provides a unique opportunity to re- view traditional practices and develop rational standards based on latest knowledge and technology. The national standards of metric countries

reflect different practices just as British and U.S. standards frequently re- flect different practices. Therefore, the present period when international

recommendations are being developed in lEC and ISO enables optimum

standards to be developed which will reduce the number of sizes of standard
DISCUSSION 131

parts and products, conserve materials by their more efficient use, and

improve the quality of product. The study on optimum metric fasteners

initiated by the Industrial Fasteners Institute (app. V) needs to be emulated

in other industries. In the past, individual companies have revised their own

standards to accomplish these objectives, but the difficulty in changing

national standards for parts and products used throughout industry have

prevented full benefits to be achieved. A principal objective of international

standardization should be to develop from the experiences of all countries

engineering standards that are superior to existing national standards and

which will conserve the worlds resources. After international standards

are established, there is not likely to be another opportunity for making

changes of the magnitude required to achieve these goals.

As new practices and technologies are developed in the future, the

need for standardization beyond the company level should be considered.

Practices that require development of national standards generally require

international standardization also. Therefore, development of such standards should proceed simultaneously at the national and international levels, to the extent that this would be practical to do. Failure to do so may result

in national standards that are not in harmony and may establish practices

that are prohibitive in cost to change.

In summary, this study shows that engineering standards can be har- monized internationally without the U.S. changing its measurement units. To achieve international standardization, all countries including the U.S.

have to change many, if not most, of their engineering practices. The extent of change may be little or great, depending on the practice. The impact of

change can be mimimized by full participation in the international forum.

The measurement units in international standards are mixed at present, but

eventually they will be the International System of Units. Those involved

with the development or use of standards will have to be adept with these

units. Other parts of the U.S. Metric Study are directed to the wider use

of these units in the U.S.
APPENDIX I

PubUc Law 90-472 3Ct 82 stat. s93 To autborlze tbe Secretary of Comiueree to make a study to drtrniiine tbe advantages and disadvantages of increased use of the metric system in tbe United

Statea Be it enacted hy the Senate and House of Reprenentatlves of the United States of ATiierica in Congress assembled, That the Secretary of Metric system. Commerce is hereby authorized to conduct a program of investigation, Study, research, and survey to determine the impact of increasing worldwide

use of the metric system on tiie United States; to appraise the desir- ability and practicability of increasing the use of metric weights and

measures in the United States; to study the feasibility of retaining and promoting by international use of dimensional and other engi- neering standards based on the customary measurement units of tlie United Stfttes; and to evaluate the costs and benefits of alternative courses of action which may be feasible for the United States. Sec. 2. In carrying out the program described in the first section of investigation

this Act, the Secretary, among other things, shall— and appraisal

(1) investigate and appraise the advantages and disadvantages requirements,

to the United States in international trade and commerce, and in military and other areas of international relations, of the increased use of an internationally standardized system of weights and

measures;

(2) appraise economic and military advantages and disad- vantages of the increased use of the metric system in the United

States or of the increased use of such system in specific fields and

the impact of such increased use upon those affected

[S) conduct extensive comparative studies of the systems of

weights and measures used in educational, engineering, manufacturing, commercial, public, and scientific areas, and the rela- tive advantages and disadvantages, and degree of standardization

of each in its respective field

(4) investigate and appraise the possible practical difficulties which might De encountered in accomplishing the increased use of the metric system of weights and measures generally or in

specific fields or areas in the United States;

(5) permit appropriate participation by representatives of United States industry, science, engineering, and labor, and their

associations, in the planning and conduct of the program authorized by the first section of this Act, and in the evaluation of the information secured under such program; and

(6) consult and cooperate witli other government agencies, Federal, State, and local, and, to the extent practicable, with

foreign governments and international organizations. Sec. 3. In conducting the studies and developing the recommenda- Results of tions required in this Act, the Secretary shall give full consideration to changes in the advantages, disadvantages, and problems associated with possible measurement changes in either the system of measurement units or the related di- system, mensional and engineering standards currently used in the United

States, and specifically shall

(1) investigate the extent to which substantial changes in the

size, shape, and design of important industrial products would be

necessary to realize the benefits which might result from general use of metric unite of measurement in the United States

(2) investigate the extent to which uniform and accepted engi- neering standards based on the metric system of measurement

units are in use in each of the fields under study and compare the

extent to such use and the utility and degree of sophistication of such metric standards w ith those in use in the United States; and

(3) recommend specific means of meeting the practical diffi- culties and costs in those areas of the economy where any recom- mended change in the system of measurement units and related dimensional and engineering standards would raise significant practical difficulties or entail significant costs of conversion. Sec. 4. The Secretary shall submit to the Congress such interim Report to reports as he deems desirable, and within three years after the date of Congress, the enactment of this Act, a full and complete report of the findings made under the program authorized by this Act, together with sucli I'ecommendations as he considers to be appropriate and in the best interests of the United States. Sec. 5. From funds previously appropriated to the Department of Funds. Commerce, the Secretary is authorized to utilize such appropriated sums as are necessary, but not to exceed $500,000, to carry out the purlooses of this Act for the first year of the program.

Sec. 6. This Act shall expire thirty days after the submission of the Expiration

final report pursuant to sect ion 3. • Approved August 9, 1968.

132
APPENDIX II

UDC 53.081 : 003.62 : 004.1 Ref. No. : ISO/R 1000- 1969(E)

ISO

INTERNATIONAL ORGANIZATION FOR STANDARDIZATION

ISO RECOMMENDATION

R 1000

RULES FOR THE USE OF UNITS

OF THE INTERNATIONAL SYSTEM OF UNITS

AND A SELECTION

OF THE DECIMAL MULTIPLES AND SUB-MULTIPLES

OF THE SI UNITS

1st EDITION

February 1969

COPYRIGHT RESERVED

The copyright of ISO Recommendations and ISO Standards

belongs to ISO Member Bodies. Reproduction of these documents, m any country, may be authorized therefore only by the national standards organization of that country, being

a member of ISO.

For each individual country the only valid standard is the national standard of that country.

Printed in Switzerland

Also issued in French and Russian. Copies to be obtained through the national standards organizations.

133
134 ENGINEERING STANDARDS

BRIEF HISTORY

The ISO Recommendation R 1000, Rules for the use of units of the International System of Units and a

selection of the decimal multiples and sub-multiples of the SI units, was drawn up by Technical Committee ISO/TC 12, Quantities, units, symbols, conversion factors and conversion tables, the Secretariat of which is held by the Dansk Standardiseringsraad (DS).

Work on this question led, in 1967, to the adoption of a Draft ISO Recommendation.

In March 1968, this Draft ISO Recommendation (No. 1557) was circulated to all the ISO Member Bodies

for enquiry. It was approved, subject to a few modifications of an editorial nature, by the following .Member

Bodies :

Australia Austria Belgium

Brazil

Hungary Poland

India Romania

Iran Iraq South Africa, Rep. of

Switzerland

Czechoslovakia

Canada

Chile Israel Italy Japan

Ireland Thailand Turkey

U.A.R. Denmark

Finland France GermanyKorea, Dem. P. Rep. of Netherlands New Zealand

United Kingdom

U.S.S.R.

Two Member Bodies opposed the approval of the Draft :

Norway

Sweden

Since the publication of this Draft was a particularly urgent matter, the ISO Council decided, at its 1967

meeting, that the document be published as an ISO RECOMMENDATION after its approval by the ISO Member

Bodies.
APPENDIX II 135

ISO/R 1 000- 1969(E)

ISO Recommendation R 1000 February 1969

RULES FOR THE USE OF UNITS

OF THE INTERNATIONAL SYSTEM OF UNITS

AND A SELECTION

OF THE DECIMAL MULTIPLES AND SUB-MULTIPLES

OF THE SI UNITS

1. SCOPE

This ISO Recommendation gives rules for the use of units of the International System of Units and for forming and selecting decimal multiples and sub-multiples of the SI units for application in the various fields of technology.

2. GENERAL

2.1 The name Systeme International d'Llnites (International System of Units), with the abbreviation SI, was adopted by the 1 1 th Conference Generale des Poids et Mesures in l')60. The coherent units are designated "SI units".

2.2 The International System of Units is based on the following six base-units :

metre ( m ) ampere (A)

kilogramme (kg) kelvin(K)

second (s) C3ndela(cd)

as units for the base-quantities : length, mass, time, electric current, thermodynamic temperature, and luminous intensity.

2.3 The SI units for plane angle and solid angle, the radian (rad) and the steradian (sr) respectively, are called supplementary units in the International System of Units.
136 ENGINEERING STANDARDS

ISO/R 1000-1969(E)

2.4 The expressions for the derived SI units are stated in terms of base-units; for example, the SI unit for velocity is metre per second (m/s). For some of the derived SI units special names and symbols exist; those approved by the Conference

Generale des Poids et Mesures are listed below :

Quantity

Naiti6 of SI unit Symbol

Expressed in terms

of basic or derived

SI units

frequency hertz Hz 1 Hz = 1 s~'

force newton N 1 N = 1 kgm/s^

work, energy, quantity of heat joule J 1 J = 1 N m

power watt W 1 W = 1 J/s

quantity of electricity coulomb c 1 C = 1 A s

electric potential, potential difference, tension, electromotive

force volt V 1 V = 1 W/A

electric capacitance farad F 1 F = 1 A s/V

electric resistance ohm n 1 n = 1 V/A

flux of magnetic induction, magnetic flux weber Wb I Wb = 1 V s

magnetic flux density, magnetic induction tesla T 1 T = 1 Wb/m^

inductance henry H 1 H = 1 Vs/A

luminous flux lumen Im 1 Im = 1 cdsr

illumination lux Ix 1 Ix = 1 Im/m^

It may sometimes be advantageous to express derived units in terms of other derived units having special names; for example, the SI unit of electric dipole moment (A s m) is usually expressed as C m.
APPENDIX II 137

ISO/R 1000-I969(K|

2.5 Decimal multiples and sub-multiples of the SI units are formed by means of the prefixes given below

Factor by which the unit is multiplied Prefix Symbol

10'^ tera T

10' G

10' mega . M

10^ kilo k

10^ hecto h

10 deca da

10-' deci d

10-^ centi c

10-^ milli m

10"* micro 1^

10-* nano n

10-'^ pico P

10-' = femto f

10-" atto a

The symbol of a prefix is considered to be combined with the unit symbol to which it is directly attached, forming with it a new unit symbol which can be raised to a positive or negative power and which can be combined with other unit symbols to form symbols for compound units.

Examples 1 cm' = (10-^m)' = IO-*m'

l|is-' = (lO-'s)-' = lO's"'

1 mm^/s = (10-'m)^/s = lO-'mVs

Compound prefixes should not be used; for example, write nm (nanometre) instead of mpim.
138 ENGINEERING STANDARDS

ISO/R 1000 1 969(E)

3. RULES FOR THE USE OF SI UNITS AND THEIR DECIMAL MULTIPLES AND SUB-MULTIPLES

3.1 The SI units are preferred, but it will not be practical to limit usage to these; in addition, therefore, their decimal multiples and sub-multiples, formed by using the prefixes, are required.

In order to avoid errors in calculations it is essential to use coherent units. Therefore, it is strongly recommended that in calculations only SI units themselves be used, and not their decimal multiples and

sub-multiples.

3.2 The use of prefixes representing 10 raised to a power which is a multiple of 3 is especially recommended.

Note. - in certain cases, to ensure convenience in the use of the units, this recommendation cannot be followed; column 5 of the tables in the Annex gives examples of these exceptions.

3.3 It is recommended that only one prefix be used in forming the decimal multiples or sub-multiples of a derived SI unit, and that this prefix be attached to a unit in the numerator.

NOTE. - In certain cases convenience in the use requires attachment of a prefix to both the numerator and the denominator at the same time, and sometimes only to the denominator. Column 5 of the tables in the Annex gives examples of these exceptions.

4. NUMERICAL VALUES

4.1 When expressing a quantity by a numerical value and a certain unit it has been found suitable in most

applications to use units resulting in numerical values between 0.1 and 1000. The units which are decimal multiples and sub-multiples of the SI units should therefore be chosen to provide values in this range; for example.

observed or

calculated values can be expressed as

1 2 000 N ! 2 kN

0.00394 m 3.94 mm

14010 N/m^ 14.01 kN/m^

0.0003 s 0.3 ms

4.2 The rule according to clause 4.1 cannot, however, be consistently applied. In one and the same context the numerical values expressed in a certain unit can extend over a considerable range; this applies especially to tabulated numerical values. In such cases it is often appropriate to use the same unit, even when this means exceeding the preferred value range 0.1 to 1000.

4.3 Rules for writing symbols for units are given in ISO Recommendation R 31, Part . . . * : General

principles concerning quantities, units and symbols.

5. LIST OF UNITS

For a number of commonly used quantities, examples of decimal multiples and sub-multiples of SI units, as well as of some other units which may be used, are given in the Annex to this document.

At present at the stage of draft proposal.
APPENDIX II 139

ISO/R 10001969 (E) ANNEX

g 2

f. S r-a

o E

- 9- E t« O E^

U 3 3 O ^ ^ Cfl e -o c w O « « c — "O ,t

cj c a> ?5 « 4* — ±i - E .S•

s E i

, o

E 3

E E

E E

E E

422-764 OL - 71 - 10
14U

ISO/R 1000-1969 (E) ANNEX

In

1964

tlie

Conference

Generale

des

Poids

et

Mesures

adopted

the

name

litre

(1)

as

the

synonym

for

cubic

decimetre

(dm')

but

discouraged

the

use

of

the

name

litre

for

precision

measurements

Other

units

such

as

week,

month

and

year

(a)

are

in

common

use

.

1

knot

=

0.514

444

m/s

PART

11:

PERIODIC

AND

RELATED

PHENOMENA

3

E B

-a '->

II II "e "b "b "b O o CD O

^11 II ^ 11 c^ II £ ~ E _

£ s _ _ jj - E

" 5 s £ day

(d),

Id

=

24h

hour

(h),

1

h

=60

min

minute

(min),

1

min

=

60s

kilometre

per

hour

(km/h)

1

km/h

=Tr:rm/si.b

revolution

per

minute

revolution

per

second

"e "b

rr

_2 E i c

N N N I I I I

H o s S

"e s

(second)

rad/s m/s Hz

(hertz)

volume time

angular

velocity velocity

frequency

rotational frequency

(1) 1-5.1

,

1-6.1 op

1-10.1 2-3.1 2-3.2
APPENDIX II 141

ISO/R 10001969(E) ANNEX

Remarks

PART

III

MECHANICS

The

metric

carat

(1

metric

carat

=2

X

10"*

kg)

is

used

for

commercial

transactions

in

diamonds,

fine

pearls

and

precious

stones.

For

litre

(1)

see

item

1-5.1

Other

units

or

other

names

of

units

which

may

be

used oo o

11

cc

o

c

~So

II

~00 J£

II

_E

t— ~ao

Other

decimal

multiples

and

sub-multiples

of

SI

unit

00 ^ II zno

Selection

of

recommended

decimal

multiples

and

submultiples

of

SI

unit

M oo

"e

"So ZzS E a.

SI

unit

(kilogramme)

"do kg

m/s

OO "e00 M N

(newton)

Quantity

mass density (mass

density)

momentum

moment

of

momentum,

angular

momentum

moment

of

inertia force and

weight

Item

No. in

ISO/R

31

3-1.1 3-2.1 3-5.1 3-6 1

3-7.1 3-8.1 3-8.2
142 ENGINEERING STANDARDS

ISO/R 1000-1969 (E) ANNEX

5i3i c

s: 2

« 3 3

ST 8

Z E g

-3 zz

? z

—

.5 .3

o

i

II >

O O

X on\ i %

2 S rn

II

lec id T—

= 1

» S 3: O S 5
APPENDIX II 143

ISO/R 1000-1969 (E) ANNEX

Remarks

PART

IV

:

HEAT

11

Other

units

or

other

names

of

units

which

may

be

used

degree

Celsius

(°C)

o

Other

decimal

multiples

and

sub-multiples

of

SI

unit

o —

>

Selection

of

recommended

decimal

multiples

and

submultiples

of

SI

unit

P 3 2 3 E

SI

unit

K

(kelvin)

Li

"e

Quantity

impact strength

thermodynamic

temperature

Celsius

temperature temperature

interval

linear

expansion coefficient

heat,

quantity

of

heat heat

flow

rate

density

of

heat

flow

rate

Item

No. in

ISO/R

31

4-11 4-2,1 4-1,1 4,2,1

1

4-3.1 t4-5.1 4-6.1
144 ENGINEERING STANDARDS

ISO/R 1000 1969(E) ANNEX

1^

$

0

?

oo 3 3

do

MJ/kg kJ/kg MJ/kg kJ/kg

B?

oo

5"

oo oo

.:<:

thermal

conductivity

coefficient

of

heat

transfer

heat

capacity

specific

heat

capacity >,

a.o

c

specific

entropy

specific

energy

specific

latent

heat

4

«' d

4 4 4

•44 4

004

146 ENGINEERING STANDARDS

ISO/R 1000-1969 (E) ANNEX

"eoO

"eo

'k Z j>i E

u_ tt. u. E rL C Cl.

_E ^_E

i c o.

ik "e

'4 ^

V

(volt) \ o F

(farad) F/m \o

Cm

electric

potential

and

potential

difference,

tension and

electromotive

force

displacement

electric

flux,

flux

of displacement capacitance

permittivity

electric

polarization

electric dipole

moment

5-6.1 5-6.2 5-6.3 5-7.1 5-9.1

5-11.1 5-12.1 5-17.2 5-18.1
APPENDIX II 147

ISO/R 1000- 1 969(E) ANNtX

Remarks

Other

units

or

other

names

of

units

which

may

be

used

3

Other

decimal

multiples

and

sub-multiples

of

SI

unit ll< <

A/mm A/cm A/mm A/cm

Wb/mm

Selection

of

recommended

decimal

multiples

and

submultiples

of

Si

unit

kA/m kA/m ^

< 1fa

mWb kWb/m

SI

unit

<

A/m A/m < T

(tesla) Wb

(weber) Wb/m

Quantity

current density

linear

current

density

magnetic

field

strength

magnetic potentia]

difference magnetic

flux

density,

magnetic

induction

flux

of

magnetic

induction, magnetic

flux

magnetic

vector

potential

Item

No. in

ISO/R

31

.S-19.1

5-20.1 5-21.1 5-23.1 5-24.1 5-25.1 5-26.1
148 ENGINEERING STANDARDS

ISO/R 1000-1969(E) ANNEX

1s

=m

The

name

"Siemens"

and

the

symbol

"S"

are

adopted

by

lEC

and

ISO,

but

not

so

far by

CGPM.

c

ijE

4i

A/mm

^ 3: X I c i c a.

E E

kA/m H

E 0 2 J.; E i

H

(henry) H/m "e<

A/m H

<

Z 3: G

self

inductance

and

mutual

inductance

permeability

electromagnetic

moment, magnetic

moment

magnetization

magnetic

polarization

magnetic

dipole

moment resistance

conductance

5-27.1 5-27.2 5-29.1 5-34.1 5-35.1 1
APPENDIX II 149

ISO/R 1000 19^9 (H ) ANNEX

EG

.1 i

w Si 3

w -O I/)

8

.S- Q.

H 1

E = E Pee

G G c; 9 C5 G

« o

-i g E

3 is 3 "aa

E

E 13
150 ENGINEERING STANDARDS
APPENDIX II 151

ISO/R 1000 I -ihy (E) ANNEX

Remarks

For

litre

(1)

see

item

l-.'i.l

.

<.)ther

units

or

other

names

of

units

which

may

be

used

"oc

— -5" ° = ^ g E E

^ ^

J2 - 11 i!

'e^

kmol/kg

mol/kg

Other

decimal

multiples

and

sub-multiples

of

SI

unit

Selection

of

recommended

decimal

multiples

and

submultiples

of

SI

unit

SI

unit

"e E

Quantity

molar

entropy

molarity molality diffusion

coefficient

thermal

diffusion

coefficient

j

Item

No. in

ISO/R

31

(1)

8-9.1

8-13.1 8-15.1 8-36.1 8-38.1

Date of the first printing May 1969

Price based on 25 pages
APPENDIX III METRIC PRACTICE GUIDE

(A Guide to the Use of SI — the International System of Units)

ASTM Designation: E 380 - 70

AMERICAN SOCIETY FOR TESTING AND MATERIALS

1916 Race St., Philadelphia, Pa., 19103

152
APPENDIX III 153

Prepared by Committee on Metric Practice: A. G. Cook, Chairman

Coordinator of Product Specifications, Allegheny Ludlum Steel Corp. R. P. Lukens, Secretary

Standards Editor, ASTM

R. B. Belford

Technical Director, Industrial Fasteners Institute R. P. Destito

Manager, Specifications & Standards Section, Revere Copper & Brass

Inc. K. C. Ford

Professional Engineer, Canadian Standardization Association Testing

Laboratories

J. D. Graham

Manager, Engineering Research, International Harvester Co.

R. R. Heldenfels

Chief, Structures Research Div., Langley Research Center, National

Aeronautics and Space Administration

A. A. Jones

Chief Engineer — Administrative, Anaconda Wire and Cable Co.

A. F. Jones

Chief, Research and Engineering Support Div., Army Materials and

Mechanics Research Center

J. A. Liska

Chief, Division of Wood Engineering Research, U. S. Forest Products

Laboratory

Bryant Mather

Chief, Concrete Div., U. S. Army Engineers, Waterways Experiment

Station

A. G. McNish

National Bureau of Standards Manager, Metric Study Program, Oflice

of Invention and Innovation

R. D. Stiehler (alternate to Mr. McNish)

National Bureau of Standards Manager, Standards Survey. U. S. Metric

Study
154 ENGINEERING STANDARDS

Designation: E 380 - 70

AMERICAN SOCIETY FOR TESTING AND MATERIALS

1916 Race St., Philadelphia, Pa., 19103

Reprinted from the Annual Book of ASTM Standards Copyright.

Standard

METRIC PRACTICE GUIDE*

(A Guide to the Use of SI — the International

System of Units)

This Standard is issued under the fixed designation E 380; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of

last reapproval. Foreword

To continue to serve the best interests of the public through science and industry the American Society for Testing and Materials is actively cooperating with other stand- ardization organizations in the development of simpler and more universal metrology

practices. In some industries both here and abroad, the U.S. customary units are gradually being replaced by those of a modernized metric' system known as the International System of Units (SI). Recognizing this trend, the Society considers it important

to prepare for broader use of SI units through coexistence of these two major systems.

This policy involves no change in standard dimensions, tolerances, or performance

specifications.

Contents

Section Scope 1 SI LJnits and Symbols 2 Base Units '

! 2.1.1 Supplementary Units 2.1.2 Derived Units 2.1.3 Multiple and Submultiple Units 2.1.4 Rules for SI Style and Usage 3 General 3.1 Application of Prefixes 3.2 Non-SI Units 3.3 Usage for Selected Quantities 3.4 Style 3.5 Rules for Conversion and Rounding 4 General 4.1 Rounding Values 4.2 Significant Digits 4.3 Dimensions and Tolerances 4.4 Other Units 4.5 Appendixes

Terminology Al

Development of the International System of Units A2

Conversion Factors for Physical Quantities A3

* This guide is under the jurisdiction of the ASTM Committee on Metric Practice. A list of members may be found m the ASTM Yearbook.

Current edition accepted March 19. 1970. Originally issued 1964 without designation as ASTM Metric Practice Guide, revised 1966. Adopted as standard 1968. Replaces E 380 - 68. An Act of Congress in 1866 declared that "u shall be lawful throughout the Llnited States of America to employ

the weights and measures of the metric system." In 1893 an Executive Order directed that "the office of weights and

measures ... will in the future regard the international prototype meter and kilogram as fundamental standards, and

the customary units, the yard and the pound, will be derived therefrom in accordance with the act of July 28, 1866."
APPENDIX 111 155

9 E 380

1. Scope

1.1 This Metric Practice Guide deals with

the conversion, from one system of units to another, of quantities that are in general use, and includes the units most frequently used in the various fields of science and industry. The

conversion factors given are from U.S. cus- tomary units" to those of the International System of Units' which is officially abbreviated as SI in all languages.

1.2 The recommendations contained herein' are based upon the following premises, which

are believed to represent the broadest base

for general agreement among proponents of

the major metrology systems:

1.2.1 That for most scientific and technical work the International System of Units is generally superior to other systems; and that

this system is more widely accepted than any

other as the common language in which scientific and technical data should be expressed.

This is particularly true for the fields of electrical science and technology since the com- mon electrical units (ampere, volt, ohm, etc.) are SI units.

1.2.2 That various U.S. customary units, particularly the inch and the pound, will continue to be used for some time.

1.2.3 That unit usage can and should be

simplified; that one means toward such simplification is the elimination of obsolete and

unneeded units; and that another is a better understanding of the rational links between SI

units and units of other systems.

2. SI Units and Symbols

2.1 The SI system consists of six base

units, two supplementary units, a series of derived units consistent with the base and

supplementary units, and a series of approved

prefixes for the formation of multiples and

submultiples of the various units. 2.1.1 Base Units:'''

Quantity length mass

time

electric current thermodynamic temperature luminous intensity

2.1.2 Supplementary Units:

plane angle

solid angle

2.1.3 Derived Units:^

acceleration

activity (of a radioactive source) angular acceleration angular velocity area

density

electric capacitance

electric field strength

electric inductance

electric potential difference

electric resistance

Unit meter kilogram

second ampere

kelvin candela

radian

steradian

meter per second squared

disintegration per second

radian per second squared

radian per second

square meter kilogram per cubic meter

farad

volt per meter

henry

volt

' ohm

SI Symbol m

kg

sA

K

cd

rad

sr

Formula

m/s"

(disintegration/s) rad/s" rad/s m"kg/m'

A-s/V

V/m

V . s/A

W/A

V/A

"This and other terms are defined in Appendix Al. 'The International System of Units (Systeme International d'Unites) (SI) is described in Appendix A2.

'This section is adapted from IEEE Recommended Practice for Units in Published Scientific and Technical Work, IEEE Spectrum, March 1966, pp. 169-173. The six base and two supplementary units are defined in Appendix A2. In chemistry a further base unit has been considered necessary. The use of the mole (symbol-mol) for this purpose corresponding to the base quantity "amount of sub- stance," is recommended by the ISO.

* These units will be used in the International System of Units (SI) without prejudice to other units that may be added

in the future. The Advisory Committee on Units of the International Committee of Weights and Measures has recommended the pascal (Pa) as the name for the unit of pressure or stress instead of the newton per square meter; thus the unit for viscosity becomes the pascal-second. The Committee also recommended the name Siemens (S) as the name for the unit of electrical conductance instead of the reciprocal ohm or the ampere per volt.

422-764 OL - 71 - 11
156 ENGINEERING STANDARDS

E 380

Qusntity I Ini* unit ol aymoo For electromotive force volt V W./A

energy joule J N -m

entropy joule per kelvin J/K

force newton N

' kg • m/s'

frequency hertz Hz (cycle)/s illumination lux Ix \m/Tn^ luminance candela per square meter cd/m'

luminous flux lumen Im ca • sr magnetic field strength ampere per meter A/m

magnetic flux weber Wb V . s magnetic flux density tesia T Wb/m'

magnetomotive force ampere A

power watt W J/s

pressure'^ newton per square meter N/m'

quantity of electricity coulomb c A • s quantity of heat joule J N-m

radiant intensity watt per steradian W/sr

specific heat joule per kilogram-kelvin J/kg • K

stress*" newton per square meter N/mthermal conductivity watt per meter-kelvin W/m • K

velocity meter per second m/s

viscosity, dynamic newton-second per square meter N; s/mviscosity, kinematic square meter per second m'/s

voltage volt V W/A

volume' cubic meter m

wavenumber reciprocal rheter (wave)/m work joule J N m

2.1.4 Multiple and Submultiple Units (see 3.2):

Multiplication Factors Prefix SI Symbol

1 000 000 000 000 10'^ tera T

1 000 000 000 10' giga G

1 000 000 lO*" mega M

1 000 10' kilo k

100 10- hecto* h 10 10' deka* da

0.1 10' deci* d

0.01 10

' centi* c 0.001 10

' milli m

0.000 001 10

' micro M 0.000 000 001 10

' nano n 0.000 000 000 001 10

'^ pico P 0.000 000 000 000 001 10'^ femto f 0.000 000 000 000 000 001 10 atto a

* Not recommended but occasionally used.

3. Rules for SI Style and Usage

3.1 General—The established SI unitsbase, supplementary, derived, and combinations thereof (see Section 2, SI Units and

Symbols) with appropriate multiple or sub- multiple prefixes—should be used. To maintain the coherence of the system, multiples or submuitiples of SI units should not be used

in combinations to form derived units or in equations.

3.1.1 Mixed Units—The use of mixed

units, especially those compounded from different systems, should be avoided. For example,

use kilogram per cubic meter (kg/m'), not kilo- gram per gallon (kg/gal), use 0.1789 rad or 10.25 deg, not 10 deg 15 min, and

use 12.75 Ibm, not 12 lb 12 oz.

3.2 Application of Prefixes:

3.2.1 General—Approved prefixes (2.1.4)

' In 1964 the General Conference on Weights and Measures adopted the name hter as a special name for the cubic decimeter but discouraged the use of the name liter for volume measurement of extreme precision.
APPENDIX III 157

should be used to indicate orders of magnitude, thus eliminating insignificant digits and

decimals, and providing a convenient substi- tute for writing powers of 10 as generally pre- ferred in computation. For example,

12 300 m or i2.3 X 10 ' m becomes 12.3 km,

and

0.0123 ^,A or 12.3 X 10 "A becomes 12.3 nA.

3.2.2 Selection—Multiple and submultiple

prefixes representing steps of 1000 are recom- mended. For example, show force in mN, N,

kN, and length in mm, m, km, etc. The use of centimeters should be avoided unless a strong reason exists. An exception is made in the case of area and volume used alone (see 3.2.5). 3.2.3 Double prefixes and hyphenated prefixes should not be used. For example.

use GW (gigawatt), not kMW, and

use pF (picofarad), not ^j^F. 3.2.4 Combination Units—Prefixes should

not be used in the denominator of compound

units, except for the kilogram (kg). Since the kilogram is a base unit of SI, this particular

multiple is not a violation and should be used

in place of the gram; for example, use 200

J/kg, not 2 dJ/g. Prefixes may be applied to the numerator of a combination unit, thus, meganewton per square meter (MN/m') or

for greater clarity, mega(newton per square

meter), but not newton per square centimer

(N/cm") nor newton per square millimeter (N/mm-).

3.2.5 With SI units of higher order such as m" and m', the prefix is also raised to the same order; for example, mm' is lO^'^m' not

10" 'm '. In such cases, the use of cm", cm ', dm", dm', and similar non-preferred prefixes

is permissible.

3.3 Non-SI Units —Certain metric units

that are not SI (such as kilogram-force) have been widely used in engineering practice.

Consequently, certain deviations from SI may

be used during a transition period, but should

definitely be discouraged. These deviations

are discussed below.

3.4 Usage for Selected Quantities:

3.4.1 Mass, Force, and Weight:

3.4.1.1 The principal departure of SI from

the more familiar form of metric engineering

units is the use of the newton as the unit of

force instead of the kilogram-force. Likewise,

the newton instead of kilogram-force is used

E 380

in combination units including force; for ex- ample, pressure or stress (N/m"), energy (N • m = J), and power (N m/s = W).

3.4.1.2 The term "mass" (unit = kilo- gram) is used to specify the quantity of matter

contained in material objects and is independent of their location in the universe. The term "weight" (unit = newton) is used as a measure of gravitational force acting on a material

object at a specified location and generally

varies as the object changes location (see Fig.

1). Although a constant mass has an approximately constant weight on the surface of the

earth, the pound-force and the kilogram-force

are, to high accuracy, not the forces exerted by the earth's gravitation on a pound-mass or

a kilogram-mass in locations that depart sig- nificantly from mean sea level. The gravitational force varies by about 0.5 percent over

the Earth's surface. Therefore, the variation of gravity must be taken into account when

greater accuracy is required. For convenience,

the precise expression of forces on a gravitational basis is related to the International standard gravity value ("standard accelera- tion") 9.80665 m/s". For example: a man of

72.5 kg mass in Washington, D.C., which is near sea level, would weigh, at standard gravity, 72.5 kg X 9.806 65 m/s' or 711 N,

whereas the same man at an elevation such as

that of Denver, Colorado, would weigh only

72.5 kg X 9.796 12 m/s' or 710 N.

3.4.1.3 The term mass or unit mass should

be used to indicate the quantity of matter in an object, and the previous practice of using

weight in such cases should be avoided. The

term weight should be used only when specifi- cation of the gravitational forces requires it, and then it should be accompanied by a state- ment specifying the location and gravitational acceleration at that point.

3.4.1.4 If non-SI units are used for force and mass, a distinction should be made be- tween (/) force or load and (2) mass, both of which have traditionally been termed weight. For force or load, gf, kgf, or Ibf should be

used; for mass, g, kg, Ibm (preferred), or lb. 3.4.1.5 Certain physical quantities involv- ing force and mass units may cause confusion due to the use of the same name for the units of both quantities. The newton was introduced

as a unit of force to avoid this confusion, and
158 ENGINEERING STANDARDS

such problems are avoided if force and mass

units are identified and converted accordingly. For example, the combination unit foot- pound-force per pound-mass used to measure

efficiency could be considered (erroneously) to have the dimension of feet and might be converted to meters; however, considering the

definition of the units, it should be converted

to newton-meters per kilogram (N • m/kg) or

joules per kilogram (J/kg) in SI units. In many cases, the relationship between newtons,

seconds, and kilograms given by the first law

of motion (F = ma) should be used to simplify units (that is, the newton is equal to a kilogram-meter per second per second, N =

kg m/s').

3.4.2 Length:

3.4.2.1 Nominal dimensions name the

item; no SI equivalent is required (see Appendix Al for definition of "nominal"). For ex- ample, there is nothing 1 in. about a nominal

"1-in. pipe," the dimensions of which should

be converted as follows:

Nominal Outside Diameter,

in. (mm)

Wall Thickness, in. (mm)

Size, in. Sch 40 Sch 80 Sch 160

1 .315 (33,40) 0.133 0.179 0.250

(3.38) (4.55) (6.35)

Likewise, a "2 by 4" is that in name only and

refers to the approximate dimensions in inches of a rough-sawn, green piece of timber,

the finished dimensions of which are consider- ably less. A V4-2O NC screw thread should continue to be identified in this manner.

However, the controlling dimensions of the

part, such as the pitch, major, and minor di- ameters of a screw thread, should be converted to SI values in accordance with 3.1 and

3.2. Threads per inch should be converted to millimeter pitch. 3.4.2.2 When a dimension such as wire diameter or thickness of sheet and strip is expressed by a gage number, the appropriate gage system (for example, American Wire

Gage or Awg) and the corresponding SI value should be given.

3.4.2.3 Surface finish expressed in microinch should be converted to nanometer (nm).

3.4.3 Temperature—The SI temperature

scale is the International Thermodynamic

Temperature Scale, and the SI unit used is

E 380

the kelvin; therefore kelvins should be used to express temperature and temperature inter- vals as the preferred unit. However, wide use

is made of the degree Celsius, particularly in engineering and in non-scientific areas, and it will be permissible to use the Celsius scale where considered necessary. The Celsius scale (formerly called the centigrade scale) is re- lated directly to the kelvin scale as follows:

One degree Celsius equals one kelvin, exactly. A Celsius temperature (r) is related to a kelvin temperature (7) as follows:

T = 273.15 + ;, exactly

In using temperature information of extreme

precision, the International Practical Temperature Scale must be recognized, because much

available data are based upon it. This consists of international agreement on certain fixed points to permit calibration of instruments. Some of these fixed points are known to contain errors, but the differences between the Thermodynamic and the Practical scales are of no consequence in almost all temperature

considerations. The basis of the practical scale

is given in Footnote 13. 3.4.4 Time—The preferred SI unit for time

rates or total time is the second. However,

because of practical advantages in the use of

hours, minutes, and days, etc. for certain purposes, these units are permissible.

3.4.5 Angles—The radian is the preferred SI unit. Decimal multiples of the radian or degree are preferred; however, the arc degree, arc minute, and arc second may be used for the measurement of plane angles. Solid angles should be measured in steradians.

3.4.6 Stress and Pressure—The correct unit

for pressure and stress is the newton per square meter. Prior to the adoption of SI, the

units kilogram-force per square centimeter or kilogram-force per square millimeter were commonly used in engineering in metric countries. These units may be used in addition to, but not in place of, N/m^ as an interim proce- dure in order to maintain communication with engineering groups in metric countries during

their transition to SI units. Where the kilo- gram is used as a unit of force, it shall be so designated (kgO to distinguish it clearly from

the unit of mass (kg).
APPENDIX III 159

3.4.7 Other Quantities —Other units that have been widely used in engineering may

continue to be used in addition to, but not in place of, the SI units. Such units include the horsepower to measure mechanical power and

the torr to measure air pressure. These exceptions are interim procedures during the transi- tion to SI units and are not intended to be permanent protection for irregular practices.

Such practices should be eliminated as rapidly

as possible.

3.5 St vie: 3.5.1 Capitalization—Symbols for SI units are not capitalized unless the unit is derived from a proper name; thus, Hz for H. R.

Hertz, but m for meter. Unabbreviated units are not capitalized, for example, hertz, newton, and kelvin. Numerical prefixes and their symbols are not capitalized, except for the symbols T, G, and M (mega) (see 2.1.4). 3.5.2 Plurals—Unabbreviated SI units form their plurals in the usual manner. SI symbols are always written in singular form. For example,

50 newtons or 50 N, and

25 grams or 25 g.

3.5.3 Punctuation —Periods should not be used after SI unit symbols except at the end

of a sentence.

3.5.4 Number Grouping—To facilitate the reading of numbers having four or more digits, the digits should be placed in groups of

three separated by a space instead of commas

counting both to the left and to the right of

the decimal point. In the case of four digits the spacing is optional. This style also voids confusion caused by the European use of commas to express decimal points. For example, use

1 532 or 1532 instead of 1,532 132 541 816 instead of 132,541,816 983 769.816 78 instead of 983,769.81678

3.5.5 Equations—When U.S. customary

units appear in equations, the SI equivalents should be omitted. Instead of inserting the SI equivalents in parentheses as in the case of

text or small tables, the equations should be

restated using SI quantities or a sentence, paragraph, or note added stating the factor to be used to convert the calculated result in U.S. units to the preferred SI units.

E 380

3.5.6 Derived Units—In derived unit ab- breviations use the center dot to indicate multiplication and a slash to indicate division. Symbols to the left of the slash are in the numerator and those to the right in the de- nominator.

4. Rules for Conversion and Rounding

4.1 General:

4.1.1 Unit conversions should be handled

with careful regard to the implied correspondence between the accuracy of the data and the given number of digits. 4.1.2 In all conversions, the number of sig- nificant digits retained should be such that accuracy is neither sacrificed nor exaggerated.

4.1.3 The most accurate equivalents are obtained by multiplying the specified quantity

by the conversion factor exactly as given in Appendix A3 and then rounding in accord- ance with 4.2 to the appropriate number of

significant digits (see 4.3). For example, to convert 11.4 ft to meters: 11.4 X 0.3048 =

3.474 72, which rounds to 3.47 m (see 4.3.6). 4.1.4 There is less assurance of accuracy when the equivalent is obtained by first rounding the conversion factor to the same number

of significant digits as in the specified quantity, performing the multiplication, and then rounding the product in accordance with 4.3. This procedure may provide approximate val- ues but it is not recommended for tolerances

or limiting values. For example, again converting 11.4 ft to meters: 11.4 X 0.305 =

3.4770 which rounds to 3.48 m (see 4.3.6). This compares with the value of 3.47 m ob- tained by the more exact method of 4.1.3. 4.1.5 Unless greater accuracy is justifiable, the equivalents should be rounded in accord- ance with the applicable values in Table I. 4.1.6 Converted values should be rounded

to the minimum number of significant digits that will maintain the required accuracy, as discussed above. In certain cases slight deviation from this practice to make use of convenient or whole numbers may be feasible, in which case the word "approximate" must be used following the conversion. For example,

1 7a in. = 47.625 mm exact = 47.6 mm normal rounding
160 ENGINEERING STANDARDS

= 48 mm (approx) rounded to whole number = 47.5 mm (approx) rounded to preferred number

Other examples:

Determine the breaking load of a specimen 20 in. (approx 500 mm) long. Take individual specimens about I yd (1 m) long. Cut a speciman approximately 4 by 6 in. (100 by

150 mm).

4.1.6.1 A quantity stated as "not more

than" is not "nominal." For example, a speci- men al least 4 in. wide requires a width of at

least 101 .6 mm.

4.1.7 The practical aspects of measuring must be considered when using SI equivalents. If a scale divided into Vieths of an inch

is suitable for making the original measurements, a metric scale having divisions of 1 mm is obviously suitable for measuring the length and width in SI units, and the equivalents should not be reported closer than the nearest millimeter. Similarly, a gage or cali- per graduated in divisions of 0.02 mm is comparable to one graduated in divisions of 0.001

in., and equivalents should be similarly indi- cated. Analogous situations exist in mass,

force, and other measurements.

4.1.8 Where dimensional interchangeability

is involved, the methods described in 4.4.2 should be employed. Selection of Method A

or Method B will depend upon the functional interchangeability required and on the rela- tionship of the limits in the original dimensioning system to the limits of mating or re- lated parts. 4.1.9 Appendix A3 contains conversion fac- tors that give exact (as defined in terms of the base units) or tive-figure (or better) accuracy

for implementing these rules. 4.2 Rounding Values:*^ 4.2.1 When a figure is to be rounded to fewer digits than the total number available, the procedure should be as follows:

4.2.1.1 When the first digit discarded is less than 5, the last digit retained should not be changed. For example, 3.463 25, if rounded to four digits, would be 3.463: if rounded to three digits, 3.46. 4.2.1.2 When the first digit discarded is greater than 5, or if it is a 5 followed by at least one digit other than 0, the last figure re- tained should be increased by one unit. For

E 380

example 8.376 52, if rounded to four digits, would be 8.377: if rounded to three digits, 8.38.4.2.1.3 When the first digit discarded is exactly 5, followed only by zeros, the last digit retained should be rounded upward if it is an odd number, but no adjustment made if it is an even number. For example, 4.365, when

rounded to three digits, becomes 4.36. 4.355 would also round to the same value, 4.36, if rounded to three digits. 4.3 Significant Digits^

4.3.1 When converting integral values of

units, consideration must be gi''en to the implied or required precision of the integral value to be converted. For example, the value "4 in." may be intended to represent 4, 4.0, 4.00, 4.000, 4.0000 in., or even greater accuracy. Obviously, the converted value must be

carried to a suflFicient number of digits to maintain the accuracy implied or required in the original quantity.

4.3.2 Any digit that is necessary to define

the specific value or quantity is said to be sig- nificant. When measured to the nearest meter,

a distance may be recorded as 157 m; this number has three significant digits. If the measurement had been made to the nearest

0.1 m, the distance may have been 157.4 m;

this number has four significant digits. In each of these cases the value of the right-hand

digit was determined by measuring the value of an additional digit and then rounding to the desired degree of accuracy. In other words,

157.4 was rounded to 157; in the second case, the measurement in hundredths, 157.36 was

rounded to 157.4. 4.3.3 Zeros may be used either to indicate

a specific value, like any other digit, or to in- dicate the magnitude of a number. The 1960

population figure rounded to thousands was

179 323 000. The six left-hand digits of this number are significant: each of them measures a value. The three right-hand digits are zeros which merely indicate the magnitude of

^ Adapted from "American National Standard Practice

for Inch-Millimeter Conversion for Industrial Use." ANSI

B48. 1-1933 (R1947), ISO R37(l 1964.

" See also ASTM Recommended Practice E 29, for Indi- catmg Which Places of Figures Are to Be Considered Significant in Specified Limiting Values, Annual Book of ASTM Standards. Part 30.
APPENDIX III 161

the number rounded to the nearest thousand. This point may be further illustrated by the following list of estimates and measurements,

each of which is of different magnitude but each of which has only one significant digit:

1000

100

100 .01 0 .001 0.0001

4.3.4 Occasionally data required for an

investigation must be drawn from a variety of sources where they have been recorded with varying degrees of refinement. Specific rules must be observed when such data are to be

added, subtracted, multiplied, or divided.

4.3.5 The rule for addition and subtraction

is that the answer shall contain no significant

digits farther to the right than occurs in the

least accurate figure. Consider the addition of

three numbers drawn from three sources, the

first of which reported data in millions, the second in thousands, and the third in units:

163 000 000

217 885 000

96 432 768

477 317 768 The total indicates a precision that is not

valid. The numbers should first be rounded to one significant digit farther to the right than

that of the least accurate number, and the sum taken as follows:

163 000 000

217 900 000

96 400 000

477 300 000 The answer is then rounded to 477 000 000 as

called for by the rule. Note that if the second

of the figures to be added had been

217 985 000, the rounding before addition would have produced 218 000 000, in which

case the 0 following 218 would have been a

significant digit. 4.3.6 The rule for multiplication and divi- sion is that the product or quotient shall contain no more significant digits than are contained in the number with the fewest signifi- cant digits used in the multiplication or divi- sion. The difference between this rule and the

rule for addition and subtraction should be

E 380

noted: the latter rule merely requires rounding of digits that lie to the right of the last significant digit in the least accurate number.

The following illustration highlights this dif- ference:

Multiplication; 113.2 X 1.43 = 161.876, rounded to 162

Division: 113. 2 1.43 = 79.16, rounded to 79.2 Addition: 113.2 + 1.43 = 114.63, rounded to 1 14.6 Subtraction: 113.2 - 1.43 = 111.77, rounded to 1 1 1 .8 The above product and quotient are limited to three significant digits since 1.43 contains

only three significant digits. In contrast, the rounded answers in the addition and subtraction examples contain four significant digits. 4.3.7 Numbers used in the above illustra- tions have all been estimates or measurements. Numbers that are exact counts are

treated as though they consist of an infinite number of significant digits. More simply

stated, when a count is used in computation

with a measurement the number of significant

digits in the answer is the same as the number

of significant digits in the measurement. If a count of 40 is multiplied by a measurement of

10.2, the product is 408. However, if 40 were

an estimate accurate only to the nearest 10, and hence contained but one significant digit, the product would be 400.

4.4 Dimensions and Tolerances:^"

4.4.1 Dimensions Without Tolerances:

4.4.1.1 If no tolerance is given and the dimension is not approximate, give the converted dimension in millimeters to one additional significant digit when the first digit in the SI value is smaller than the first digit in the U.S. customary value. For example, 5.4

in. = 137.16 mm, which rounds to 137 mm. When the first digit in the SI value is larger than the first digit in the U.S. customary value, round the converted dimension to the same number of significant digits as given in the U.S. customary value. For example, 2.3

in. = 58.42 mm, which rounds to 58 mm. In

tool, gage, and similar work it is usually ad-

"' Parts of this section are adapted from SAE Recommended Practice J916 (1968 SAE Handbook). Parts of S.\E J916 were based on the earlier edition of the ASTM

Metric Practice Guide.
162 ENGINEERING STANDARDS

<lSlb E 380

visable to limit the millimeter equivalent to not more than three decimal places, as this represents as high a precision as is ordinarily

required.

4.4.1.2 If no tolerance is given and the dimension is approximate, calculate the converted dimension in millimeters to one additional significant digit and round appropriately. If the rounded converted dimension is given to fewer significant digits than the origi- nal dimension, insert the word "approximately" before the converted dimension. For example, 77 in. = 1.9558 m, which rounds to approx 2 m.

4.4.1.3 If the dimensions are given in common fractions of an inch, give the converted dimensions in millimeters to the implied or required precision of the value to be

converted.

4.4.1.4 As an alternative to 4.1.3 and 4.1.4, conversion tables and charts are frequently

provided for the rapid determination of converted values of commonly used quantities by

addition only. Table 2 is of this type, and provides values for converting inches to millimeters. In using this table, the inch value to be converted should be written to as many deci- mal places as accuracy requires. The value should then be split into groups of not more

than two significant digits each. The inch equivalent of each group should be taken from

Table 2 and tabulated as in the following

example, proper regard being given to the position of the decimal point in each case. For

example, to convert 2.4637 in. to millimeters,

2.0000 in. = 50.800 00 mm exactly 0.4600 in. = 11.684 00 mm exactly 0.0037 in. = 0.093 98 mm exactly

2.4637 in. = 62.577 98 mm exactly

or, correct to three decimal places: 2,4637 in, = 62.578 mm

In this example, to maintain accuracy during

conversion without retaining an unnecessary number of digits, the rounded millimeter

equivalent of each group is carried to one dec- imal place more than the inch value being

converted. The sum of the group of equivalents is then rounded to one less decimal place than the original inch value. 4.4.1.5 Table 3 provides values for the conversion of decimal and fractional values of an

inch to millimeters. Combinations of inch and

fractional inch-millimeter equivalents may be

tabulated to obtain the desired millimeter conversion. As in the example in 4,4,1,4, the mil- limeter valu^ should be rounded to one less than the decimal equivalent of the inch frac- tion taken to the intended or implied accuracy.

4.4.2 Toleranced Dimensions—The use of

the exact relation 1 in. = 25.4 mm generally

produces converted values containing more

decimal places than are required for the desired accuracy. It is, therefore, necessary to round these values suitably and at the same

time maintain the degree of accuracy in the converted values compatible with that of the original values.

4.4.2.1 General—The number of decimal

places given in Table 4 for rounding toler- anced dimensions relates the degree of accuracy to the size of the tolerance specified. Two

methods of using this table are given: Method

A, which rounds to values nearest to each limit, and Method B, which rounds to values al- ways inside the limits. In Method A, rounding is effected to the nearest rounded value of the limit, so that, on

the average, the converted tolerances remain

statistically identical with the original toler- ances. The limits converted by this method,

where acceptable for interchangeability, serve as a basis for inspection.

In Method B, rounding is done systematically toward the interior of the tolerance zone

so that the converted tolerances are never

larger than the original tolerances. This

method must be employed when the original

limits have to be respected absolutely, in particular, when components made to converted

limits are to be inspected by means of original gages. Method A —The use of this method ensures

that even in the most unfavorable cases nei- ther of the two original limits will be exceeded

(nor diminished) by more than 2 percent of

the value of the tolerance. Proceed as follows:

(a) Calculate the maximum and minimum

limits in inches.

(b) Convert the corresponding two values

exactly into millimeters by means of the conversion factor 1 in. = 25.4 mm (see Table 2).

(c) Round the results obtained to the near-
APPENDIX III 163

est rounded value as indicated in Table 4, depending on the original tolerance in inches,

that is, on the difference between the two limits in inches. Method B This method must be employed

when the original limits may not be violated, as in the case of mating parts. In extreme cases, this method may increase the lower limit a maximum of 4 percent of the tolerance and

decrease the upper limit a maximum of 4 per- cent of the tolerance.

(a) Proceed as in Method A, steps (a) and

(b).(b) Round each limit toward the interior of

the tolerance, that is, to the next lower value

for the upper limit and to the next higher

value for the lower limit:" For example,

A dimension is expressed in inches as 1.950 ±0.016

The limits are 1.934 to 1.966 Conversion of the two limits

into millimeters gives 49. 1 236 to 49.9364 Method A~—l\\e. tolerance equals 0.032 in. and thus

lies between 0.01 and 0.1

in. (see Table 4). Rounding

these values to the nearest 0.01 mm, the values in millimeters to be employed

for these two limits are 49. 12 to 49.94 Method fi — Rounding to- wards the interior of the

tolerance, millimeter values

for these two limits are 49.13 to 49.93 This reduces the tolerance to 0.80 mm instead of 0.82 mm given by Method A.

4.4.2.2 Special Methods for Nominal Size and Deviations —In order to avoid accumulation of rounding errors, the two limits of size must be converted separately; thus, they must

first be calculated if the dimension consists of

a basic size and two tolerances. However

(except when Method B is specified) as an al- ternative, the basic size may be converted to the nearest rounded value and each of the tol- erances converted toward the interior of the tolerance. This method, which sometimes

makes conversion easier, gives the same max- imum guarantee of accuracy as Method A, but usually results in smaller converted toler- ances. 4.4.2.3 Special Methods for Limitation

Imposed by Accuracy of Measurements

the increment of rounding given for the toler- ances in Table 4 is too small for the available accuracy of measurement, limits that are acE 380

ceptable for interchangeability must be deter- mined separately for the dimensions. For

example, where accuracy of measurement is limited to 0.001 mm, study shows that values converted from 1.0000 ± 0.0005 in. can be rounded to 25.413 and 25.387 mm instead of 25.4127 and 25.3873 mm with little disadvantage, since neither of the two original limits is exceeded by more than 1.2 percent of the tol- erance.

4.4.2.4 Positional Tolerance If the dimensioning consists solely of a positional tolerance around a point defined by a nontoleranced

basic dimension, the basic dimension must be converted to the nearest rounded value and

the positional variation (radius) separately

converted by rounding downwards, these roundings depending on twice the original

radial tolerance, that is, the diameter of the tolerance zone.

4.4.2.5 Toleranced Dimension Applied to a Nontoleranced Position Dimension — If the toleranced dimension is located in a plane, the position of which is given by nontoleranced

basic or gage dimension, such as when dimensioning certain conical surfaces, proceed as

follows:

(a) Round the reference gage arbitrarily, to the nearest convenient value.

(b) Calculate exactly, in the converted unit of measurement, new maximum and mini- mum limits of the specified tolerance zone, in the new plane defined by the new basic di- mension.

(c) Round these limits in conformity with

the rules given in 4.2. For example, a cone of

taper 0.05 in. /in. has a diameter of 1.000 ±

0.002 in. in a reference plane located by the nontoleranced dimension 0.9300 in. By virtue of the taper of the cone, the limits of the toler- ance zone depend on the position of the refer- ence plane. Consequently, if the dimension

0.9300 in. = 23.6220 mm is rounded to 23.600 mm, that is, a reduction of 0.022 mm, each of

the two original limits, when converted ex- actly into millimeters, must be corrected by

0.022 X 0.05 = 0.0011 mm, in the appropriate sense, before being rounded.

" If the digits to be rounded are zeros, the retained digits remain unchanged.
164 ENGINEERING STANDARDS

4.4.2.6 Consideration of Maximum and

Minimum Material Condition—The ability to assemble mating parts depends on a "go"

condition at the maximum material limits of

the parts. The minimum material limits which

are determined by the respective tolerances are often not as critical from a functional standpoint. Accordingly, it may be desirable

to employ a combination of Methods A and B

in certain conversions by using Method B for the maximum material limits and Method A

for the minimum material limits. Alternatively, it may be desirable to round automatically

the converted minimum material limits outside the original limits to provide greater tol- erances for manufacturing.

4.5 Other Units:

4.5.1 Temperature^ThQ tolerances for converting from degrees Fahrenheit to kelvins or degrees Celsius are given in Table 5. All temperatures expressed in a whole number of degrees Fahrenheit should be converted to the nearest 0.1 kelvin (or degree Celsius) with the following exceptions:

4.5.1.1 Fahrenheit temperatures indicated

to be approximate, a maximum, a minimum,

or to have a tolerance of ±5 F or more should

be converted to the nearest whole number in

E 380

kelvins or degrees Celsius and rounded to the appropriate number of significant digits, for example,

100 ± 5 F = 38 ± 3 C

1000 ± 50 F = 540 ± 30 C

4.5.2 Pressure or Stress—Convert by one of

the following factors and round in accordance

with 4.2 and 4.3:

1 psi = 6.894 757 kN/m'

1 ksi = 6.894 757 MN/m'

4.5.2.1 Alternatively, psi or ksi may be

converted to kN/m^ or MN/m^ by the use of Table 6. Converted values determined from

the table should be rounded in accordance

with 4.2 and 4.3. 4.5.2.2 Pressure or stress values having an

uncertainty of more than 2 percent may be converted without rounding by the approxi- mate factors:

1 psi = 7 kN/m"

1 ksi = 7 MN/m'

4.5.2.3 Pressure or stress values in kgf/mm^

may be converted to MN/m' by the use of Table 7. Converted values determined from

the table should be rounded in accordance

with 4.2 and 4.3.
APPENDIX III 165

E 380

APPENDIXES

Al. Terminology

A 1.1 To help ensure consistently reliable conversion and rounding practices, a clear understanding

of the related nontechnical terms is a prerequisite. Accordingly, certain terms used in this Guide are defined as follows: accuracy (as distinguished from precision)—the degree of conformity of a measured or calculated value to some recognized standard or specified value. This concept involves the systematic error of an operation, which is seldom negligible. approximate— describes a value that is nearly but

not exactly correct or accurate.

deviation —variations from a specified dimension or design requirement, usually defining upper and

lower limits. (See also tolerance.)

digit—one of the ten Arabic numerals (0 to 9) by which all numbers are expressed. dimension—a geometric element in a design, such

as length, angle, etc., or the magnitude of such a quantity. feature—an individual characteristic of a part, such

as screw-thread, taper, slot, etc. figure (numerical) —an arithmetic value expressed

by one or more digits. nominal —describes a value assigned for the purpose

of convenient designation: existing in name only. precision (as distinguished from accuracy) —the degree of mutual agreement between individual measurements, namely repeatability and reproducibility. significant (as applied to a digit)- any digit that is

necessary to define a value or quantity (see Footnote 9). tolerance -the total range of variation (usually bi- lateral) permitted for a size, position, or other required quantity; the upper and lower limits between which a dimension must be held. U.S. customary units -units based upon the yard and the pound commonly used m the United

States of America and defined by the National Bureau of Standards (Ref 14). Some of these

units have the same name as similar units in the United Kingdom (British, English, or U.K. units) but are not necessarily equal to them. Three terms that may be encountered in the liter- ature dealing with the modernized metric system

are "metricize,'" "metrication," and "rationalize." These have been defined as follows: metricize— to convert any other unit to its metric

(SI) equivalent. This may be an exact, a rounded,

or a rationalized equivalent. For example, a 2-in.

test specimen becomes 50.8 mm by exact conversion; 51 mm by rounding in accordance with Section 4, Rules for Conversion and Rounding, and

50 mm when rationalized, metrication—any act tending to increase the use of

the metric system (SI), rationalize—to round completely a converted value

to a popular standard figure compatible with noncritical mating components, interchangeable

parts, or other nominal sizes in a series.

A2. Development of the International System of Units

Le Systeme Internationa! d'Unites

.^2.1 The decimal system of units was first conceived in the 16th century when there was a great confusion and jumble of units of weights and measures. It was not until 1790, however, that the French

National Assembly requested the French Academ>

of Sciences to work out a system of units suitable

for adoption b\ the entire world. This s>slem, based

on the meter as a unit of length and the gram as a

unit of mass, was adopted as a practical measure to benefit industry and commerce. Physicists soon re- alized its advantages and it was adopted also in sci- entific and technical circles. The importance of the regulation of weights and measures was recognized

in Article 1, Section 8, when the United States Constitution was written in 1787, but the metric system was not legalized in this country until 1866.

In 1893, the international meter and kilogram be- came the fundamental standards of length and mass

in the United States, both for metric and customary

weights and measures. A2.2 Meanwhile, international standardization began with an 1870 meeting of 15 nations in Paris

that led to the May 20, 1875, International Metric

Convention, and the establishment of a permanent

International Bureau of Weights and Measures near

Paris. A General Conference on Weights and Measures (CGPM) was also constituted to handle all in- ternational matters concerning the metric system. The CGPM nominally meets every sixth year in Paris and controls the International Bureau of Weights and Measures which preserves the metric

standards, compares national standards with them, and conducts research to establish new standards. The National Bureau of Standards represents the United States in these activities. A2.3 The original metric system provided a co-
166 ENGINEERING STANDARDS

herent set of units for the measurement of length, area, volume, capacity, and mass based on two fun- damental units: the meter and the kilogram. Measurement of additional quantities required for science and commerce has necessitated development of additional fundamental and derived units. Numerous

other systems based on these two metric units have

been used. A unit of time was added to produce the centimeter-gram-second (cgs) system adopted in 1881 by the International Congress of Electricity. About 1900 practical measurements in metric units began to be based on the meter-kilogram-second

(MKS) system. In 1935 Prof. Giovanni Giorgi rec- ommended that the MKS system of mechanics be

linked with the electromagnetic system of units by

adoption of one of the units—ampere, coulomb,

ohm, or volt —for the fourth basic unit. This recom- mendation was accepted and in 1950 the ampere,

the unit of electrical current, was established as a basic unit to form the MKSA system. A2.4 The 10th CGPM in 1954 adopted a ration- alized and coherent system of units based on the four MKSA units, plus the degree Kelvin as the

unit of temperature and the candela as a unit of luminous intensity. The llth CGPM in 1960 for- mally gave it the full title. International System of

Units, for which the abbreviation is "SI" in all lan- guages. Thirty-six countries, including the United

States, participated in this 1960 conference. The

12th CGPM in 1964 made some refinements, and

the 13th CGPM in 1967 redefined the second, re- named the unit of temperature as the kelvin (K), and revised the definition of the candela. A2.5 SI is a rationalized selection of units from

the metric system which individually are not new. It includes a unit of force (the newton) which was in- troduced in place of the kilogram-force to indicate by its name that it is a unit of force and not of mass.

SI is a coherent system with six base units for which

names, symbols, and precise definitions have been

established. Many derived units are defined in terms of the base units, symbols assigned to each, and, in some cases, given names, as for example,

the newton (N). A2.6 The great advantage of SI is that there is one and only one unit for each physical quantity

the meter for length (/), kilogram (instead of gram)

for mass (m). second for time (/), etc. From these elemental units, units for all other mechanical

quantities are derived. These derived units are defined by simple equations such as r = d//d/

(velocity), a = dv/di (acceleration), F = ma (force), W = Fl (work or energy), P = W/t (power). Some

of these units have only generic names such as meter per second for velocity; others have special names such as newton (N) for force, joule (J) for work or energy, watt (W) for power. The SI units

for force, energy, and power are the same regardless of whether the process is mechanical, electrical, chemical, or nuclear. A force of I newton applied

for a distance of I meter can produce I joule of

heat, which is identical with what 1 watt of electric power can produce in 1 second. A2.7 Corresponding to the advantages of the SI system, which result from the use of a unique unit

for each physical quantity, are the advantages which

result from the use of a unique and well-defined set of symbols and abbreviations. Such symbols and

abbreviations eliminate the confusion that can arise

E 380

from current practices in different disciplines such

as the use of b for both the bar (a unit of pressure) and bam (a unit of area). A2.8 Another advantage of the SI is its retention of the decimal relation between multiples and sub- multiples of the base units for each physical quan- tity—not that there is anything inherently superior

in a number system to the base 10 but that SI con- forms to the system of Arabic numericals. Prefixes are established for designating multiple and sub- multiple units from "tera" (10'") down to "atto"

( 10 ' ) for convenience in writing and talking. A2.9 Another major advantage of the SI system

is its coherence. A system of units is coherent if the product or quotient of any two unit quantities in the system is a unit of the resulting quantity. For example, in any coherent system, unit area results when

unit length is multiplied by unit length, unit velocity when unit length is divided by unit time, and unit force when unit mass is multiplied by unit acceleration. Thus, in a coherent system in which the foot is a unit of length, the square foot is the unit of area

(but the acre is not). Similarly in a coherent system

in which the foot, the pound, and the second are

units of length, mass, and time, the unit of force is the poundal (and not the pound-weight or the pound-force). A2.10 Whatever the system of units, whether it be coherent or noncoherent, magnitudes of some

physical quantities must be arbitrarily selected and

declared to have unit value. These magnitudes form

a set of standards and are called base units. All other units are derived units related to the base

units by definition. The six base SI units are each

very accurately defined in terms of physical meas- urements that can be made in a laboratory, except

the kilogram, which is a particular mass preserved

by the International Bureau of Weights and Measures.A2.1I Various other units are associated with SI

but are not a part thereof. They are related to units of the system by powers of 10 and are employed in specialized branches of physics. Examples of such

units are the bar, a unit of pressure, approximately

equivalent to one atmosphere and equal exactly to

1()0 kilonewtons per square meter. It is employed

extensively by meterologists. Another such unit is the gal (galileo) equal exactly to an acceleration of

0.01 meter per second". It is used in geodetic work.

These, however, are not consistent units, that is to say, equations involving both these units and SI

units cannot be written without a factor of proportionality even though the factor of proportionality is a simple multiple of 10. A2.I1.1 Originally (1795) the liter was intended

to be identical with the cubic decimeter. The Third General Conference on Weights and Measures,

meeting in 1901, decided to define the liter as the volume occupied by the mpss of one kilogram of pure water at its maximum density under normal

atmospheric pressure. Careful determinations sub- sequently established the liter so defined as being

equivalent to 1.000028 dm'. In 1964 the General Conference on Weights and Measures withdrew this definition of the liter, and declared that the word

"liter" was a special name for the cubic decimeter. Thus its use is permitted in SI, but is discouraged,

since it creates two units for the same quantity, and

its use in precision measurements might conflict
APPENDIX III 167

E 380

with measurements recorded under the old definition.A2.12 Authorized translations of the original French definitions of the six base and two supple- mentary units of the International System are given

in the following paragraphs:

A2.12.1 Meier—The meter is the length equal to

1 650 763.73 wavelengths in vacuum of the radiation corresponding to the transition between the

levels 2pi„ and 5d=, of the krypton-86 atom, (adopted

at 11th CGPM 1960) A2.12.2 Kilogram —The kilogram is the unit of mass; it is equal to the mass of the international prototype of the kilogram, (adopted at 1st and 3rd CGPM 1889 and 1901) A2.12.3 Second—The second is the duration of

9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom.'' (adopted at 13th CGPM 1967) A2.12.4 Ampere—The ampere is that constant

current which, if maintained in two straight parallel conductors of infinite length, of negligible cross section, and placed one meter apart in vacuum, would

produce between these conductors a force equal to 2 X 10" newton per meter of length, (adopted at 9th CGPM 1948) A2.12.5 Kelvin—The kelvin, unit of thermody- namic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water." (adopted at 13th CGPM 1967) A2.12.6 Candela—The candela is the luminous

intensity, in the perpendicular direction, of a sur- face of 1 /600 000 square meter of a blackbody at the temperature of freezing platinum under a pres- sure of 101 325 newtons per square meter, (adopted

at 13th CGPM 1967) A2.12.7 Radian—The unit of measure of a plane

angle with its vertex at the center of a circle and

subtended by an arc equal in length to the radius, (adopted at 11th CGPM 1960)

A2.12.8 Steradian —The unit of measure of a

solid angle with its vertex at the center of a sphere and enclosing an area of the spherical surface equal

to that of a square with sides equal in length to the

radius, (adopted at 1 1th CGPM 1960)

''This definition supersedes (he emphemeris second as

the unit of time. "The International Practical Kelvin Temperature Scale

of 1968 and the International Practical Celsius Temperature Scale of 1968 are defined by a set of interpolation equations based on the following reference temperatures": K

Hydrogen, solid-liquid-gas equilib- rium 13.81 Hydrogen, liquid-gas equilibrium at

'33 330.6 N/m' (25/76 standard

atmosphere) 17.042 Hydrogen, liquid-gas equilibrium 20.28 Neon, liquid-gas equilibrium 27.102 Oxygen, solid-liquid-gas equilibrium 54.361 Oxygen, liquid-gas equilibrium , 90.188 Water, solid-liquid-gas equilibrium 273.16 Water, liquid-gas equilibrium 373.15

Zinc, solid-liquid equilibrium 692.73

Silver, solid-liquid equilibrium 1235.08 Gold, solid-liquid equilibrium 1337.58

deg C

-259.34

-256.108 -252.87 - 246.048 -218.789 -182.962

0.01 100.00 419.58

961.93

1064.43

° Except for the triple points and one equilibrium hydro- gen point (17.042 K) the assigned values of temperature are

for equilibrium states at a pressure

p„ = 1 standard atmosphere (101 325 N/m").

In this scale the degree Celsius and the kelvin are identical, and are related by an exact dilTerence of 273.15 degrees. It is seldom necessary to recognize the differences between the thermodynamic and practical scales, but the General Conference of Weights and Measures in 1960 es- tablished the following quantity symbols for use if desired: Thermodynamic temperature:

Practical temperature:

kelvins degrees Celsius

kelvins degrees Celsius

A2.13 Definitions of Derived Units of the International System Having Special Names:

Physical Quantity A2.13.1 Electric capacitance

A2.I3.2 Electric inductance

A2.13.3 Electric potential difference (electromotive force)

A2.13.4 Electric resistance

A2.13.5 Energy

A2.13.6 Force

Unit and Definition The farad is the capacitance of a capacitor between the plates of which there appears a difference of potential of one volt when

it is charged by a quantity of electricity equal to one coulomb. The henry is the inductance of a closed circuit in which an electro- motive force of one volt is produced when the electric current in the circuit varies'urtiformly at a rate of one ampere per second.

The volt (unit of electric potential difference and electromotive

force) is the difference of electric potential between two points of

a conductor carrying a constant current of one ampere, when the power dissipated between these points is equal to one watt. The ohm is the electric resistance between two points of a conductor when a constant difference of potential of one volt, applied be- tween these two points, produces in this conductor a current of one ampere, this conductor not being the source of any electro- motive force. The joule is the work done when the point of application of a force of one newton is displaced a distance of one meter in the direction of the force. The newton is that force which, when applied to a body having a mass of one kilogram gives it an acceleration of one meter per second per second.
168 ENGINEERING STANDARDS

E 380

Physical Quantity A2.13.7 Frequency

A2.I3.8 Illumination

A2.I3.9 Luminous flux

A2.l3.iO Magnetic flux

A2.13.il Magnetic flux density

A2.13.I2 Power

A2.13.13 Quantity of electricity

A2.I4 Probable Acceptance of "PascaT' and

"Siemens" —The Advisory Committee on Units of

the International Committee of Weights and Measures has recommended the pascal (Pa) as the name

for the unit of pressure or stress instead of the newUnit and Definition The heriz is a frequency of one cycle per second. The lux is the luminous intensity given by a luminous flux of one lumen per square meter. The lumen is the luminous flux emitted in a solid angle of one ster- adian by a point source having a uniform intensity of one candela. The weber is the magnetic flux which, linking a circuit of one turn, produces in it an electromotive force of one volt as it is reduced

to zero at a uniform rate in one second. The lesla is the magnetic flux density given by a magnetic flux of one weber per square meter. The wati is the power which gives rise to the production of energy at the rate of one joule per second. The coulomb is the quantity of electricity transported in one second

by a current of one ampere.

ton per square meter; thus the unit for viscosity becomes the pascal-second. The Committee also recommended the name Siemens (S) as the name for the unit of electrical conductance instead of the re- ciprocal ohm or the ampere per volt.

A3. Conversion Factors for Physical Quantities'

A3. 1 General The following tables of conversion factors are intended to serve two purposes: A3. 1.1 To express the definitions of miscella- neous units of measure as exact numerical multiples of coherent "metric" units. Relationships that are exact in terms of the base units are followed by an

asterisk. Relationships that are not followed by an

asterisk are either the results of physical measurements, or are only approximate.

A3. 1.2 To provide multiplying factors for converting expressions of measurements given by numbers and miscellaneous units to corresponding new

numbers and metric units. A3. 2 Notation: A3. 2. 1 Conversion factors are presented for ready adaptation to computer readout and elec- tronic data transmission. The factors are written as

a number greater than one and less than ten with

six or less decimal places. This number is followed by the letter E (for exponent), a plus or minus symbol, and two digits which indicate the power of 10 by which the number must be multiplied to obtain

the correct value. For example,

3.523 907 E-02 is 3.523 907 X 10 or 0.035 239 07.

Similarly,

3.386 389 E+03 is 3.386 389 x 10' or 3 386.389.

A3. 2. 2 An asterisk (*) after the sixth decimal

place indicates that the conversion factor is exact and that all subsequent digits are zero. All other conversion factors have been rounded to the figures given in accordance with 4.2. A3. 3 Organization: A3. 3.1 The conversion factors are listed in two ways— alphabetically and classified by physical

quantity. The alphabetical list contains only those

units that have specific names; compounded units derived from the specific units are given in the classified list. The classified list emphasizes the more

frequently used units and contains both specific and compounded units. A3. 3.2 The conversion factors for other compounded units can easily be generated from numbers given in the alphabetical list by the well-known

rules for manipulating units. These rules, being

adequately discussed in many science and engineering textbooks, are not repeated here.

ALPHABETICAL LIST OF UNITS

(Symbols of SI units given in parentheses)

To convert from to Multiply by abampere ampere (A) 1.000 000*E +OI abcoulomb coulomb (C) 1 .000 000*E+OI

abfarad farad (F) 1.000 000*E+09

abhenry henry (H) 1.000 000' E- 09 abmho mho" 1.000 000* E+09

abohm ohm (!2) 1.000 000* E- 09

abvolt volt (V) 1.000 000* E- 08

acre meter' (m') 4.046 856 E-f 03 ampere (international of 1948) ampere (A) 9.998 35 E-01

" Based on E. A. Mechtly (Ref 19).
APPENDIX III 169

W E 380

To convert from to Multiply by angstrom meter (m) 1.000 000*E- 10 astronomical unit meter (m) 1.495 98 E+II

atmosphere (normal) newion/meter' (N/m') 1.013 250*E+05

atmosphere (technical = 1 kgf/cm') ... newton/meter' (N/m") 9.806 650*E+04

bar newton/meter- (N/m') 1.000 000* E+05

barn meter' (m') 1.000 000* E- 28

barrel (for petroleum, 42 gal) meter' (m') 1.589 873 E-OI

British thermal unit (International Table)" joule (J) 1.055 056 E+03

British thermal unit (mean) joule (J) 1.055 87 E+03

British thermal unit (thermochemical) joule (J) 1.054 350 E+03

British thermal unit (39 F) joule (J) . . 1.059 67 E+03

British thermal unit (60 F) joule (J) 1.054 68 E+03

bushel (U.S.) meter'' (m') 3.523 907 E-02

caliber meter (m) 2.540 000* E- 04

calorie (International Table) joule (J) 4.186 800* E+00

calorie (mean) joule (J) 4.190 02 E+00

calorie (thermochemical) joule (J) 4.184 000*E+00

calorie (ISC) joule (J) 4.185 80 E+00

calorie (20 C) joule (J) 4.18190 E+00

calorie (kilogram. International Table) joule (J) 4.186 800*E+03

calorie (kilogram, mean) joule (J) 4.190 02 E+03

calorie (kilogram, thermochemical) . . joule (J) 4.184 000*E+03

carat (metric) kilogram (kg) 2.000 000* E- 04

centimeter of mercury (0 C) newton/meter' (N/m"') 1.333 22 E+03

centimeter of water (4 C) newton/meter' (N/m') 9.806 38 E+01

centipoise newton-second/meter' (N s/m") 1.0(X) 000*E-03

circular mil meter' (m') 5.067 075 E- 10

clo kelvin-meter'/watt (K . m'/W) 2.003 712 E-01

coulomb (international of 1948) coulomb (C) 9.998 35 E-01

cup meter' (m') 2.365 882 E-04

curie disintegration/second 3.700 000*E+10

day (mean solar) second (s) 8.640 000 E+04

day (sidereal) second (s) 8.616 409 E+04

degree (angle) radian (rad) 1.745 329 E — 02

degree Celsius kelvin (K) = + 273.15

degree centigrade see 3.4.3 degree Fahrenheit degree Celsius tc = Uf — 32)/1.8 degree Fahrenheit kelvin (K) /k = ('f + 459.67)/ 1

.

degree Rankine kelvin (K) fK = ?r/I.8 decibar newton/meter' (N/m') 1.000 000*E+04

dyne newton (N) 1 .000 000*E-05

electron volt joule (J) 1.602 10 E-19

EMU of capacitance farad (F) 1.000 000* E+09 EMU of current ampere (A) 1.000 000* E+01

EMU of electric potential volt (V) 1.000 000* E- 08 EMU of inductance henry (H) 1.000 000* E- 09 EMU of resistance ohm (fi) 1.000 000* E- 09 ESU of capacitance farad (F) 1.112 6 E-12

ESU of current ampere (A) 3.335 6 E-10

ESU of electric potential volt (V) 2.997 9 E+02

ESU of inductance henry (H) 8.987 6 E+11

ESU of resistance ohm («) 8.987 6 E+11

erg joule (J) 1.000 000*E-07

farad (international of 1948) farad (F) 9.995 05 E-01

faraday (based on carbon- 12) coulomb (C) 9.648 70 E+04

faraday (chemical) coulomb (C) 9.649 57 E+04

faraday (physical) coulomb (C) 9.652 19 E+04

fathom meter (m) 1.828 800*E+00

fermi (femtometer) meter (m) 1 .000 000* E - 1

5

fluid ounce (U.S.) meter' (m') 2.957 353 E-05

foot meter (m) 3.048 000*E-01

foot (U.S. survey) meter (m) 1200/3937*E+00

foot (U.S. survey) meter (m) 3.048 006 E-01

foot of water (39.2 F) newton/meter"' (N/m') 2.988 98 E+03

footcandle lumen/meter' (Im/m') 1.076 391 E+01

' This value was adopted in 1956. Some of the older Inlernational Tables use the value 1.05504 E-)-03.
170 ENGINEERING STANDARDS

W E 380

To convert from to Multiply by footlambert candela/meter' (cd/m ') 3.426 259 E+00

gal(galileo) meter/second' (m/s^) 1.000 000* E- 02

gallon (Canadian liquid) meter' (m') 4.546 122 E — 03

gallon (U.K. liquid) meter' (m ') 4.546 087 E- 03

gallon (U.S. dry) meter' (m') 4.404 884 E- 03

gallon (U.S. liquid) meter' (m') 3.785 412 E-03

gamma tesla (T) 1 .000 000*E-09

gauss tesla (T) 1 .000 000*E-04

gilbert ampere-turn 7.957 747 E — 01

gill (U.K.) meter' (m') 1.420 652 E-04

gill (U.S.) meter' (m') 1.182 941 E-04

grad degree (angular) 9.000 000*E- 01 grad radian (rad) 1.570 796 E-02

grain (1/7000 Ibm avoirdupois) kilogram (kg) 6.479 891*E-05

gram kilogram (kg) 1.000 000* E-03

henry (international of 1948) henry (H) 1.000 495 E+00

horsepower (550 ft • Ibf/s) watt (W) 7.456 999 E+02

horsepower (boiler) watt (W) 9.809 50 E+03

horsepower (electric) watt (W) 7.460 000*E+02

horsepower (metric) watt (W) 7.354 99 E+02

horsepower (water) watt (W) 7.460 43 E+02

horsepower (U.K.) watt (W) 7.457 0 E+02

hour (mean solar) second (s) 3.600 000 E+03

hour (sidereal) second (s) 3.590 170 E+03

hundredweight (long) kilogram (kg) 5.080 235 E+01

hundredweight (short) kilogram (kg) 4.535 924 E+01

inch meter (m) 2.540 000*E-02

inch of mercury (32 F) newton/meter; (N/m;) 3.386 389 E+03

inch of mercury (60 F) newton/meter' (N/m") 3.376 85 E+03

inch of water (39.2 F) newton/meter ' (N/m') 2.490 82 E+02

inch of water (60 F) newton/meter" (N/m') 2.488 4 E+02

joule (international of 1948) joule (J) 1.000 165 E+00

kayser l/meter(l/m) 1.000 000*E+02

kelvin degree Celsius '< = 'k — 273.15

kilocalorie (International Table) joule (J) 4.186 800*E+03

kilocalorie (mean) joule (J) 4.190 02 E+03

kilocalorie (thermochemical) joule (J) 4.184 000*E + 03

kilogram-force (kgf) newton (N) 9.806 650*E+00

kilogram-mass kilogram (kg) 1.000 000* E+00

kilopond-force newton (N) 9.806 650*E+00

kip newton (N) 4.448 222 E+03

knot (international) meter/second (m/s) 5.144 444 E — 01 lambert candela/meter' (cd/m') •/"* E +04

lambert candela/meter" (cd/m") 3.183 099 E+03

langley joule/meter" (J/m') 4.184 000* E+04

light year meter (m) 9.460 55 E+15

liter"^ meter'(m') 1.000 000* E-03

lux lumen/meter' (Im/m-) 1.000 000*E+00

maxwell weber (Wb) 1.000 000* E- 08 micron meter (m) 1.000 000* E- 06

mil meter (m) 2.540 000*E-05

mile (international nautical) meter (m) 1.852 000*E+03

mile (U.K. nautical) meter (m) 1.853 184*E+03

mile (U.S. nautical) meter (m) 1.852 000*E+03

mile (U.S. statute) meter (m) 1.609 344* E+03

millibar newton/meter; (N/m;) 1.000 000* E+02

millimeter of mercury (0 C) newton/meter' (N/m') 1.333 224 E+02

minute (angle) radian (rad) 2.908 882 E-04

minute (mean solar) second (s) 6.000 000 E+01

minute (sidereal) second (s) 5.983 617 E+01

moment of inertia (Ibm • ft") kilogram-meter^kg • m'^) 4.214 012 E-02

moment of inertia (Ibm • in') kilogram-meter" (kg • m") 2.926 397 E — 05 moment of section' (second moment of

area) (foot') meter' (m*) 8.630 975 E-03

'" In 1964 the General Conference on Weights and Measures adopted the name liter as a special name for the cubic

decimeter. Prior to this decision the liter differed slightly (previous value, 1.000028 dm') and in expressions of precision volume measurement this fact must be kept in mind.

'

' This is sometimes called the moment of inertia of a plane section about a specified axis.
APPENDIX III 171

W E 380

To convert from to Multiply by moment of section" (second moment of

area) (inch') meter' (m') 4.162 314 E-07

month (mean calendar) second (s) 2.628 000 E+06

oersted ampere/meter (A/m) 7.957 747 E+01

ohm (international of 1948) ohm (S2) 1.000 495 E+00

ounce-force (avoirdupois) newton (N) 2.780 139 E — 01 ounce-mass (avoirdupois) kilogram (kg) 2.834 952 E — 02 ounce-mass (troy or apothecary) kilogram (kg) 3.110 348 E — 02 ounce (U.S. fluid) meter' (m') 2.957 353 E-05

parsec meter (m) 3.083 74 E-fl6

pascal newton/meter' (N/m') 1.000 000*E+00

peck (U.S.) meter' (m') 8.809 768 E-03

pennyweight kilogram (kg) 1.555 174 E — 03 perm (0 C) kilogram/newton-second (kg/N • s) 5.721 35 E— 11 perm (23 C) kilogram/newton-second (kg/N • s) 5.745 25 E— 11 perm-inch (0 C) kilogram-meter/newton-second

(kg-m/N-s) 1.453 22 E-12

perm-inch (23 C) kilogram-meter/newton-second

(kg-m/N.s) 1.459 29 E-12

phot lumen/meter' (Im/m') 1.000 000»E+04

pica (printer's) meter (m) 4.217 518 E-03

pint (U.S. dry) meter' (m') 5.506 105 E-04

pint (U.S. liquid) meter' (m') 4.731 765 E-04

point (printer's) meter 3.514 598*E-04

poise (absolute viscosity) newton-second/meter^ (N • s/m') ... 1.000 000* E — 01 poundal newton (N) 1.382 550 E-01

pound-force (Ibf avoirdupois)" newton (N) 4.448 222 E+00

pound-mass (Ibm avoirdupois)'* kilogram (kg) 4.535 924 E—01 pound-mass (troy or apothecary) kilogram (kg) 3.732 417 E — 01 quart (U.S. dry) meter' (m') 1.101 221 E-03

quart (U.S. liquid) meter' (m') 9.463 529 E-04

rad (radiation dose absorbed) joule/kilogram (J/kg) 1.000 000* E — 02

rhe meterVnewton-second (m'/N s) . . . 1.000 000*E+01

rod meter (m) 5.029 200*E+00

roentgen coulomb/kilogram (C/kg) 2.579 760*E-04

second (angle) radian (rad) 4.848 137 E-06

second (sidereal) second (s) 9.972 696 E — 01

section meter' (m') 2.589 988 E+06

section modulus (foot') meter' (m') 2.831 685 E-02

section modulus (inch') meter' (m') 1.638 706 E-05

shake second (s) 1.000 000* E- 08

slug kilogram (kg) 1.459 390 E+01

statampere ampere (A) 3.335 640 E— 10 statcoulomb coulomb (C) 3.335 640 E-10

statfarad farad (F) 1.112 650 E-12

stathenry henry (H) 8.987 554 E+11

statmho mho* 1.112 650 E-12

statohm ohm (fi) 8.987 554 E+ 1

1

statute mile (U.S.) meter (m) 1.609 344»E+03

statvolt volt (V) 2.997 925 E+02

stere meter' (m') 1.000 000* E+00

stilb candela/meter' (cd/m') 1.000 000*E+04

stoke (kinematic viscosity) meterVsecond (m7s) 1.000 000* E — 04

tablespoon meter' (m') 1.478 .676 E-05

teaspoon meter' (m') 4.928 922 E-06

tex kilogram/meter (kg/m) 1.000 000* E-06

ton (assay) kilogram (kg) 2.916 667 E-02

ton (long, 2240 Ibm) kilogram (kg) 1-016 047 E+03

ton (metric) kilogram (kg) 1 000 000*E+03

ton (nuclear equivalent of TNT) joule (J) 4.20 E+09

ton (register) meter (m') 2.831 685 E+00

ton (short, 2000 Ibm) kilogram (kg) 9.071 847 E+02

tonne kilogram (kg) 1.000 000* E+03

" The exact conversion factor is 4.448 221 615 260 5*E+00. "The exact conversion factor is 4.535 923 7*E — 01.

422-764 OL - 71 - 12
172 ENGINEERING STANDARDS

W E 380

To convert from to Multiply by

torr (mm Hg, 0 C) newton/meter-' (N/m') 1.333 22 £ +02 township meter' (m ) 9.323 957 E +07

unit pole weber (Wb) 1.256 637 E-07

volt (international of 1948) volt (absolute) (V) l.(XX) 330 E +00

watt (international of 1948) wait (W) l.(X)0 165 E+00

yard meter (m) 9.144 000*E -01

year (calendar) second (s) 3.153 600 E+07

year (sidereal) second (s) 3.155 815 E+07

year (tropical) second (s) 3.155 693 E+07

CLASSIFIED LIST OF UNITS

Acceleration

foot/second' meter/second'' (m/s") 3.048 000*E -01

free fall, standard meter/second' (m/s') 9.806 650*E+00

gal (galileo) meter/second' (m/s') 1.000 000* E- 02

inch/second-' meter/second' (m/s') 2.540 000* E- 02

Area

acre meter" (m

barn meter' (m

circular mil meter" (m

foot' meter' (m

inch" meter'^ (m

mile" (U.S. statute) meter'^ (m

section meter" (m

township meter' (m

) 4.046 856 E +03

) 1.000 000*E-28

) 5.067 075 E- 10

) 9.290 304*E-02

) 6.451 600*E-04

) 2.589 988 E+06

) 2.589 988 E+06

) 9.323 957 E+07

yard" meter' (m ') 8.361 274 E-01

Bending Moment or Torque

dyne-centimeter newton-meter (N • m) 1.000 000* E — 07

kilogram-force-meter newton-meter (N • m) 9.806 650*E +OO

ounce-force-inch newton-meter (N m) 7.061 552 E — 03

pound-force-inch newton-meter (N m) 1.129 848 E — 01 pound-force-foot newton-meter (N • m) 1.355 818 E+00

(Bending Moment or Torque)/Length

pound-force-foot/inch newton-meter/meter (N m/m) 5.337 866 E+01

pound-force-inch/inch newton-meter/meter (N • m/m) . 4.448 222 E+00

Capacity (See Volume)

Density (See Mass/Volume)

Electricity and Magnetism^"

abampere ampere (A) 1.000 0O0*E+0l

ESU means electrostatic cgs unit. EMU means electromagnetic cgs unit.
APPENDIX III 173

W E 380

To convert from to Multiply by abcoulomb coulomb (C) 1.000 000*E+01

abfarad farad (F) 1.000 OOO'E + 09 abhenrv henrv (H) 1.000 000* E- 09 abmho mho 1.000 000* E +09 abohm ohm («) 1.000 000* E- 09

abvolt volt(V) 1.000 000*E-08

ampere (international of 1948) ampere (A) 9.998 35 E-01

ampere-hour coulomb (C) 3.600 000*E +03 coulomb (international of 1948) coulomb (C) 9.998 35 E-01

EMU of capacitance farad (F) 1.000 000* E-f 09 EMU of current ampere (A) 1.000 000* E + 01 EMU of electric potential volt (V) 1 .000 000*E-08

EMU of inductance henrv (H) 1.000 000* E- 09 EMU of resistance ohm'(<2) 1.000 000* E- 09 ESU of capacitance farad (F) 1.112 6 E-12

ESU of current ampere (A) 3.335 6 E-10

ESU of electric potential volt (V) 2.997 9 E+02

ESU of inductance henry (H) 8.987 6 E+11

ESU of resistance ohm (!2) 8.987 6 E+11

farad (international of 1948) farad (F) 9.995 05 E-01

faraday (based on carbon- 12) coulomb (C) 9.648 70 E +04

faradav (chemical) coulomb (C) 9.649 57 E +04

faraday (physical) coulomb (C) 9.652 19 E +04 gamma tesla (T) 1 .000 000* E - 09

gauss tesla (T) 1.000 000* E- 04

gilbert ampere-turn 7.957 747 E-01

henry (international of 1948) henrv (H) 1.000 495 E+00

maxwell weber (Wb) 1.000 000* E- 08

oersted ampere/meter (A/m) 7.957 747 E+01

ohm (international of 1948) ohm (n) 1.000 495 E+00

ohm-centimeter ohm-meter (Si • m) 1.000 000* E- 02

statampere ampere (A) 3.335 640 E— 10 statcoulomb coulomb (C) 3.335 640 E-10

statfarad farad (F) 1.112 650 E-12

stathenry henry (H)...' 8.987 554 E+ 1

1

statmho mho 1.112 650 E-12

statohm ohm (<!) 8.987 554 E+11

statvolt volt(V) 2.997 925 E+02

unit pole weber (Wb) 1.256 637 E-07

volt (international of 1948) volt (V) 1.000 330 E+00

Energy (Inclldes Work)

British thermal unit (International Table)" joule (J) 1.055 056 E+03

British thermal unit (mean) joule (J) 1.055 87 E+03

British thermal unit (thermochemical) joule (J) 1.054 350 E +03

British thermal unit (39 F) joule (J) 1.059 67 E +03

British thermal unit (60 F) joule (J) 1.054 68 E +03

calorie (International Table) joule (J) 4.186 800*E+00

calorie (mean) joule (J) 4.190 02 E+00

calorie (thermochemical) joule (J) 4.184 000*E+00

calorie (15 C) joule (J) 4.185 80 E +00

calorie (20 C) joule (J) 4.18190 E+00

calorie (kg. International Table) joule (J) 4.186 800*E +03

calorie (kg, mean) joule (J) 4.190 02 E+03

calorie (kg, thermochemical) joule (J) 4.184 000*E+03

electron volt joule (J) 1.602 10 E-19

erg joule (J) 1.000 000* E-07

foot-pound-force joule (J) 1.355 818 E+00

foot-poundal joule (J) 4.214 011 E-02

joule (International of 1948) joule (J) 1.000 165 E+00

kilocalorie (International Table) joule (J) 4.186 800*E+03

kilocalorie (mean) joule (J) 4.190 02 E+03

kilocalorie (thermochemical) joule (J) 4.184 000*E+03
174 ENGINEERING STANDARDS

E 380

To convert from kilowatt-hour

kilowatl-hour (international of 1948)

ton (nuclear equivalent of TNT)

watt-hour

watt-second

to Multiply by joule (J) 3.600 000*E+06

joule (J) 3.600 59 E+06

joule (J) 4.20 E+09

joule (J) 3.600 000*E+03

joule (J) 1.000 000»E+00

Energy/Area Time

Btu (thermochemical)/foot" -second

Btu (lhermochemical)/foot '-minute Btu (thermochemical)/foot'-hour

Btu (thermochemical)/ inch" -second

calorie (thermochemical)/centimeter" minute

erg/centimeter -second watt/centimeter"

watt/meter- (W/m-') 1.134 893 E+04

watt/meter' (W/m') 1.891 489 E+02

watt/meter-' (W/m') 3.152 481 E+00

watt/meter-' (W/m-) 1.6.34 246 E-f 06

watt/meter- (W/m') 6.973 333 £+02

watt/meter- (W/m-) 1 .000 000* E - 03 watt/meter (W/m ) 1.000 000* E-|-04

Flow (See Mass/Time or Voelme/Time)

Force

dyne newton (N) 1.000 000* E- 05

kilogram-force newion(N) 9.806 650*E+00

kilopond-force newton (N) 9.806 650*E+00

kip newton (N) 4.448 222 E+03

ounce-force (avoirdupois) newton (N) 2.780 139 E — 01 pound-force (Ibf avoirdupois)'" newton (N) 4.448 222 E+00

pound-force (Ibf avoirdupois)'" kilogram-force"' 4.535 924 E — 01 poundal newton (N) 1.382 550 E-01

Force/Area (See Pressure)

Force/Length

pound-force/inch newion/meter (N/m) 1.751 268 E+02

pound-force/foot newlon/meter (N/m) 1.459 390 E +OI

Heat

Btu (thermochemical) in./s ft deg F

(A, thermal conductivity) watt/meter-kelvin (W/m K) 5.188 732 E+02

Btu ( Inthernalional Table) in./s ft deg 1- (A, thermal conductivity) watt/meter-kelvin (W/m K) 5.192 204 E + 02

Btu (thermochemical) in./h • ft" • deg F

(A, thermal conductivity) watt/meter-kelvin (W/m • K) 1.441 314 E-OI

Btu (International Table) in./h ft deg F (A, thermal conductivity) watt/meter-kelvm (W/m K) 1.442 279 E-01

Btu (International Table)/ft' ' joule/meter' (J/m') 1.135 653 E+04

Btu (thermochemical)/ft' joule/meter"' (J/nr) 1.134 893 E +04

Btu (International Table)/h ft' deg F

(C, thermal conductance) watt/meler'-kelvin ( W/m"' K) 5.678 263 E+00

Btu (thermochemical)/h ft" • deg F

(C. thermal conductance) . watt/meter"'-kelvin ( W/m ' K) 5.674 466 E + 00

Btu (International Table)/pound-mass joule/kilogram (j/kg) 2.326 000*E + 03

Btu (thermochemical)/pound-mass joule/kilogram (J/kg) ; 2.324 444 E+03

The metric unit of force, the newton. Is approximately I / 10 kgf.
APPENDIX III 175

E 380

To convert from Btu (International Table)/lbm deg F

(f, heat capacity) Btu (thermocheniical)/lbm • deg F

(c, heat capacity) Btu (International Table)/s ft" • deg F

Btu (thermochemical)/s • ft' • deg F

cal (thermochemical)/cm"

cal (thermochemical)/cm' • s cal (thermochemical)/cm • s • deg C . cal (International Table)/g

cal (International Table)/g • deg C . . cal (thermochemical)/g

cal (thermochemical)/g • deg C

clo deg F • h ff'/Btu (thermochemical)

(R, thermal resistance) deg F • h • ft /Btu (International Table)

{R, thermal resistance) ff/h (thermal diffusivity)

to Multiply by

joule/kilogram-kelvin (J/kg • K) . . 4.186 800*E+03

joule/kilogram-kelvin (J/kg • K) . 4.184 000 E +03

watt/meter'-kelvin (W/m' • K) 2,044 175 E+04

watt/meter'-kelvin (W/m-' • K) 2.042 808 E+04

joule/meter' (J/m;) 4.184 000*E+04

watt/meterMW/m") 4.184 000*E+04

watt/meter-kelvin (W/m • K) 4.184 000*E+02

joule/kilogram (J/kg) 4.186 800*E+03

joule/kilogram-kelvin (J/kg • K) . 4.186 800*E+03

joule/kilogram (J/kg) 4.184 000*E+03

joule/kilogram-kelvin (J/kg • K) . 4.184 000*E+03

kelvin-meterVwatt (K m'/W) 2.003 712 E-01

kelvin-meter-'/watt (K m'/W) 1.762 280 E-01

kelvin-meter'/watt (K m'/W) 1.761 102 E-01

meter-'/second (m'/s) 2.580 640*E-05

Length

angstrom meter

astronomical unit meter

caliber meter fathom meter

fermi (fermtometer) meter

foot meter

foot (U.S. survey) meter

foot (U.S. survey) meter

inch meter

league (international nautical) meter

league (statute) meter

league (U.K. nautical) meter

light year meter micron meter

mil meter

mile (international nautical) meter

mile (U.K. nautical) meter

mile (U.S. nautical) meter

mile (U.S. statute) meter

parsec meter

pica (printer's) v . . meter

point (printer's) . meter

rod meter

statute mile (U.S.) meter

yard meter

m) 1.000 000*E-10

m) 1.495 98 E+ll

m) 2.540 000*E-04

m) 1.828 800*E+00

m) 1.000 000*E-15

m) 3.048 000*E-01

m) 1200/3937*E+00

m) 3.048 006 E-01

m) 2.540 000*E-02

m) 5.556 000*E-f03 m) 4.828 032*E +03 m) 5.559 552*E +03 m) 9.460 55 E+15

m) 1.000 000*E-06

m) 2.540 000*E-05

m) 1.852 000*E +03 m) 1.853 184*E+03

m) 1.852 000*E+03

m) 1.609 344*E +03 m) 3.083 74 E+16

m) 4.217 518 E-03

m) 3.514 598*E-04

m) 5.029 200*E+00

m) 1.609 344*E+03

m) 9.144 000*E-01

Light

footcandle

footcandle footlambert

lux

lumen/meter' (Im/m ) 1.076 391 E-fOl

lux (Ix) 1.076 391 E+01

candela/meter' (cd/m') 3.426 3 E+00

lumen/meter-' (Im/m') 1.000 000* E+00

Mass

carat (metric)

grain gram

hundredweight (long)

kilogram (kg) 2.000 000*E-04

kilogram (kg) 6.479 89l*E-05

kilogram (kg) 1.000 000* E-03

kilogram (kg) 5.080 235 E+OI
176 ENGINEERING STANDARDS

E 380

To convert from hundredweight (short) kilogram-force-second /meter (mass) kilogram-mass ounce-mass (avoirdupois) ounce-mass (troy or apothecary) ^ pennyweight

pound-mass (Ibm avoirdupois)'"

pound-mass (troy or apothecary)

slug ton (assay) ton (long, 2240 Ibm)

ton (metric)

ton (short. 2000 ibm)

tonne

to kilogram (kg) 4.535 kilogram (kg) 9.806 kilogram (kg) 1.000 kilogram (kg) 2.834 kilogram (kg) 3.1 10 kilogram (kg) 1.555 kilogram (kg) 4.535 kilogram (kg) 3.732 kilogram (kg) 1 .459 kilogram (kg) 2.916 kilogram (kg) 1.016 kilogram (kg) 1.000 kilogram (kg) 9.071 kilogram (kg) 1.000Multiply by 924 E+0!

650*E+00

000*E+00

E-02

E-02

174 E-03

924 E-01

417 E-OI

390 E4-0I

667 E^02

047 E + 03 000*E+03

847 E+02

000*E+03

952

348

Mass/Area

ounce-mass/yard^ kilogram/meter" (kg/m ') 3.390 575 E — 02 pound-mass/foot' kilogram/meter" (kg/m") 4.882 428 E-t-00

Mass/Capacity (See Mass/Volume)

Mass/Time (Includes Flow)

perm (0 C) kilogram/newton-second (kg/N s) 5.721 35 E— II perm (23 C) kilogram/newton-second (kg/N s) 5.745 25 E— II perm-inch (0 C) kilogram-meter/newton-second

(kg-m/N-s) 1.453 22 E-12

perm-inch (23 C) kilogram-meter/newton-second

(kg • m/N . s) 1.459 29 E- 12 pound-mass/second kilogram/second (kg/s) 4.535 924 E — 01 pound-mass/minute kilogram/second (kg/s) 7.559 873 E — 03

ton (short, mass)/hour kilogram/second (kg/s) 2.519 958 E — 01

Mass/Volume (Includes Density and Mass Capacity)

grain (Ibm avoirdupois/7000)/gallon

(U.S. liquid) , gram/centimeter' ounce (avoirdupois)/gallon

(U.K. liquid) ounce (avoirdupois)/gallon (U.S. liquid) ounce (avoirdupois) (mass)/inch' pound-mass/foot

pound-mass/inch

pound-mass/gallon (U.K. liquid) pound-mass/gallon (U.S. liquid) slug/foot' . ton (long, mass)/yard '

kilogram-meter (kg/m') 1.711 806 E-02

kilogram/meter' (kg/m') 1.000 000*E +03

kilogram/meter' (kg/m') 6.236 027 E+00

kilogram

kilogram

kilogram

kilogram

kilogram

kilogram

kilogram

kilogram

/meter

/meter

/meter

/meter

/meter /meter

/meter /meter

(kg/m') 7.489 152 E+00

(kg/m' 1.729 994 E+03

(kg/m') 1.601 846 E+OI

(kg/m') 2.767 990 E +04 (kg/m') 9.977 644 E+OI

(kg/m') 1.198 264 E+02

(kg/m') 5.153 788 E+02

(kg/m') 1.328 939 E+03

Power

Btu (International Table)/hour

Btu (thermochemical)/second . . . Btu (thermochemical)/minute . . Btu (thermochemical)/hour

calorie (thermochemical)/second

watt (W) 2.930 71 1 E-01

watt (W) 1.054 350 E+03

watt (W) 1.757 250 E +OI watt (W) 2.928 751 E-01

watt (W) 4.184 000*E + 00
APPENDIX III 177

To convert t'rom calorie {thermochemical)/minute watt erg/second watt foot-pound-force/hour watt foot-pound-force/minute watt foot-pound-force/second . watt horsepower (550 ft • Ibf/s) watt horsepower (boiler) watt horsepower (electric) watt horsepower (metric) watt horsepower (water) watt horsepower (U.K.) watt

kilocalorie (thermochemical)/minute watt

kilocalorie (thermochemical)/second watt

watt (international of 1948) watt

# E380

to Muhipiv by W) 6.973 333 E-02

W) 1.000 000*E-07

(W) 3.766 161 E-04

(W) 2.259 697 E-02

(W) 1.355 818 E +00 [W) 7.456 999 E +02 ;W) 9.809 50 E+03

W) 7.460 000*E +02 W) 7.354 99 E+02

W) 7.460 43 E+02

W) 7.457 0 E+02

W) 6.973 333 E+01

:W) 4,184 000*E+03

(W) 1.000 165 E+00

Pressure or Stress (Force/Area)

atmosphere (normal = 760 torr) newton/meter"

atmosphere (technical = 1 kgf/cm ') newton/meter'

bar newton/meter"

centimeter of mercury (0 C) newton/meter"

centimeter of water (4 C) newton/meter"

decibar newton/meter"

dyne/centimeter" newton/meter"

foot of water (39.2 F) newton/meter"

gram-force/centimeter' newton/meter"

inch of mercury (32 F) newton/meter'

inch of mercury (60 F) newton/meter"'

inch of water (39.2 F) newton/meter

'

inch of water (60 F) newton/meter"

kilogram-force/centimeter" newton/meter'

kilogram-force/meter' newton/meter"

kilogram-force/miilimeter" newton/meter'

kip/inch" newton/meter'

millibar newton/meter"

millimeter of mercury (0 C) newton/meter'

pascal newion/meter"

poundal/foot" newton/meter"

pound-force/foot" newton/meter"

pound-force/inch" (psi) newton/meter'

pound-force/inch" (psi) kilogram-force/

psi newton/meter

torr (mm Hg, 0 C) newton/meter

N/m') 1.013 N/m-) 9.806

N/m'') 1.000 N/m') . . . 1.333 N/m'') 9.806 N/m') 1.000 N/m-') 1.000 N/m') 2.988 N/m') 9.806 N/m') 3.386 N/m') 3.376 N/m') 2.490 N/m') 2.488 N/m') 9.806 N/m') 9.806 N/m') 9.806 N/m') 6.894 N/m') 1.000 N/m') 1.333 N/m') 1.000 N/m') 1.488 N/m') 4.788 N/m' 6.894 mm'" 7.030 N/m') 6.894 N/m') 1.333

250*E+05

650*E +04 000*E +05

22 E+03

38 E +01 000*E+04

000*E-01

98 E+03

650*E+01

389 E +03

85 £ +03

82 E+02

4 E+02

650*E+04

650*E +00 650*E+06

757 E +06 000*E+02

224 E+02

000* E+00

164 E +00 026 E+01

757 E+03

696 E-04

757 E+03

22 E+02

Speed (See Velocity)

Stress (See Pressure)

Temperature

degree Celsius kelvin (K) 'k = 'c + 273.15

degree Fahrenheit kelvin (K) 'k = ('f + 459.67)/ 1.8 degree Rankine kelvin (K) /k= 'r/1-8 degree Fahrenheit degree Celsius ic = Of — 32)/1.8

kelvin degree Celsius 'c = 'k — 273.15

" The metric unit of pressure or stress is the newton per square meter (N/m ). I kgf/mm' is approximately 10' N/m' or

10 MN/m'.
178 ENGINEERING STANDARDS

E 380

To convert from Multiply by Time

day (mean solar) second (s) 8.640 000 E+04

day (sidereal) second (s) 8.616 409 E+04

hour (mean solar) second (s) 3.600 000 E +03 hour (sidereal) second (s) 3.590 170 E +03 minute (mean solar) second (s) 6.000 000 E + OI minute (sidereal) second (s) 5.983 617 E+OI

month (mean calendar) second (s) 2.628 000 E+06

second (sidereal) second (s) 9.972 696 E-01

year (calendar) second (s) 3.153 600 E +07

year (sidereal) second (s) 3.155 815 E+07

vear (tropical) second (s) 3.155 693 E+07

ToRQut (Seh Bending Moment)

Velocity (Includes Speed)

foot/hour meter/second (m/s) 8.466 fool/minute meter/second (m/s) 5.080 foot/second meter/second (m/s) 3.048 inch/second meter/second (m/s)

kilometer/hour meter/second (m/s)

knot (international) meter/second (m/s) mile/hour (U.S. statute) meter/second (m/s) mile/minute (U.S. statute) meter/second (m/s)

mile/second (U.S. statute) meter/second (m/s)

2.540

2.777

5.144 4.470

2.682

1.609 mile/hour (U.S. statute) kilometer/hour"' 1.609

667 E-05

000* E- 03 000*E-01

000* E- 02 778 E-OI

444 E-OI

400*E-01

240*E+01

344*E +03 344*E+00

Viscosity

ceniipoise newtcn-second/meter" (N s/m') 1.000 000* E — 03

centistoke . . meter'/second (m'/s) 1.000 000*E-06

fooc'/second meter'/second (m'/s) 9.290 304*E-02

poise newton-second/meter- (N • s/m") 1.000 000*E -01

poundal-second/foof' newton-second/meter" (N • s/m") 1.488 164 E +00 pound-mass/foot-second newton-second/meter" (N • s/m") ., 1.488 164 E +00

pound-force-second/foot" newton-second/meter" (N s/m") 4.788 026 E +01 rhe meter'/newton-second (m'/N • s) 1.000 000* E+OI

slug/t'oot-second newton-second/meter" (N s/m") 4.788 026 E+01

stoke meterVsecond (m '/s) 1 .000 000*E -04

Volume (Includes Capacity)

acre-foot meter * (m

barrel (oil, 42 gal) meter' (m

board foot meter' (m

bushel (U.S.) meter' (m

cup meter' (m

fluid ounce (U.S.) meter' (m

foot' meter' (m

gallon (Canadian liquid) meter' (m

gallon (U.K. liquid) meter' (m

gallon (U.S. dry) meter' (m

1.233 482 E +03

1.589 873 E-01

2.359 737 E-03

3.523 907 E-02

2.365 882 E-04

2.957 353 E-05

2.831 685 E-02

4.546 122 E-03

4.546 087 E-03

4.404 884 E-03

' Although speedometers may read km/h, the correct SI unit is m/s.
APPENDIX 111 179

W E380

To convert from to Multiply by gallon (U.S. liquid) meter' (m') 3.785 412 E-03

gill (U.K.) meter' (m') 1.420 652 E-04

gill (U.S.) meter' (m') 1.182 941 E-04

inch' " meter' (m ') 1.638 706 E- 05

liter" meter' (m') 1 .000 000*E-03

ounce (U.K. fluid) meter' (m') 2.841 305 E-05

ounce (U.S. fluid) meter' (m^) 2.957 353 E-05

peck (U.S.) meter' (m') 8.809 768 E-03

pint (U.S. dry) meter' (m') 5.506 105 E-04

pint (U.S. liquid) meter' (m') 4.731 765 E-04

quart (U.S. dry) meter' (m') 1.101 221 E-03

quart (U.S. liquid) meter' (m') 9.463 529 E-04

stere meter' (m') 1.000 000*E+00

tablespoon meter' (m') 1.478 676 E-05

teaspoon meter' (m') 4.928 922 E-06

ton (register) meter' (m') 2.831 685 E+00

yard meter' (m') 7.645 549 E-01

Volume/Time (Includes Flow)

foot'/minute meter'/second (m'/s) 4 719 474 E-04

foot /second meter'/second (m'/s) 2.831 685 E-02 mchyminute meter'/second (m'/s) 2 731 177 E-07

yard /mmute meter'/second (m'/s) 1 274 258 E-02

gallon (U.S. liquid)/day meter'/second (m'/s) 4 381 264 E-08

gallon (U.S. hquid/minute meter'/second (m'/s) 6.309 020 E-05

Work (See Energy)

References

American Society for Testing and Materials, 1916 Race St., Philadelphia, Pa. 19103:

(1) Definitions A 340, Terms, Symbols, and Conversion Factors Relating to Magnetic Testing

(2) Method D 2161, Conversion of Kinematic Viscosity to Saybolt Universal Viscosity or to Saybolt Furol

Viscosity

(3) Petroleum Measurement Tables D 1250

(4) Rec. Practice D 1914, Conversion Units and Factors Relating to Atmospheric Analysis

(5) Rec. Practice E 29, for Indicating Which Places of Figures Are to Be Considered Significant in Specified Limiting Values

American National Standards Institute, Inc., 1430 Broadway, New York, N. Y. 10018:

(6) American National Standard ZIO. 1-1941, Abbreviations for Scientific and Engineering Terms

(7) American National Standard B48. 1-1933 (R1947), Inch-Millimeter Conversion for Industrial Use,

Practice for (ISO R370-1964)

International Organization for Standardization, Geneva, Switzerland (available from American

National Standards Institute):

(8) lSO/R31/Part 1—1956, Basic Quantities and Units of the SI

(9) ISO/R31 /Part 11—1958, Quantities and Units of Periodic and Related Phenomena

(10) lSO/R31/Part III— 1960, Quantities and Units of Mechanics

(11) ISO/R31/Part IV— 1960, Quantities and Units of Heat

(12) ISO/R31/Part V— 1965, Quantities and Units of Electricity and Magnetism

(13) ISO/RIOOO— 1969, Rules for the Use of Units of the International System of Units and a Selection of

the Decimal Multiples and Sub-Multiples of the SI Units

The exact conversion factor is 1.638 706 4*E-05.
180 ENGINEERING STANDARDS

9> E 380

National Bureau of Standards (documents available from Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402):

(14) "Unit of Weights and Measures (United States Customary and Metric): Definitions and Tables of

Equivalents," A'fiS Misc. Publ. MP 233, Dec. 20, 1960

(15) Judson, L. V., "Weights and Measures Standards of the United States, a Brief History," NBS Misc.

Publ. 247, October 1963

(16) "Units and Systems of Weights and Measures. Their Origin, Development, and Present Status," A'65

Letter Circ. LC 1035, January 1960

(17) "NBS Interprets Policy on SI Units," NBS Tech. News Bull., Vol 52, No. 6, June 1968

(18) Chart—"The Modernized Metric System," NBS Spec. Publ. 304, 1968

Miscellaneous:

(19) Mechtly, E. A., "The International System of Units—Physical Constants and Conversion Factors," National Aeronautics and Space Administration, Publication SP-7012. Available from Superintendent

of Documents, U.S. Government Printing Office, Washington, D.C. 20402

(20) Palmer, J. F., "The International System of Units Handbook," Brown Engineering Co., Inc., Huntsville, Ala.

(21) McNish, A. G., "The International System of Units," Materials Research & Standards, Am. Soc. Testing Mats., Vol 5, No. 10, October 1965

(22) "Conversion Factors and Tables," British Standard 350, Part 1, 1959.

(23) "Conversion Factors and Tables," British Standard 350, Part 2, 1962.

(24) "Changing to the Metric System, Conversion Factors, Symbols, Definitions," Nat. Physical Lab., Her

Majesty's Stationery Office, London, England, 1965

(25) Metric Standards for Engineering, British Standard Handbook No. 18 (1966) Index of Terms , [

(by Section Number)

acceleration, 2.1.3 accuracy, A 1.

activity (of a radioactive source), 2.1.3 ampere, 2.1.1, 2.1.3, A2.12.4

angular acceleration, 2.1.3 angular velocity, 2.1.3 approximate, A 1.1 area, 2.1.3 candela, 2.1.1, A2.I2.6 coulomb, 2.1.3, A2. 13.13

density, 2.1.3 deviation, Al.l

digit, Al.l

dimension, Al.l

electric capacitance, 2.1.3, A2.I3.1

electric current, 2.1.1, A2.I2.4

electric field strength, 2.1.3

electric inductance, 2.1.3, A2.I3.2

electric potential difference, 2.1.3, A2.13.3

electrical resistance, 2.1.3, A2.13.4

electromotive force, 2.1.3, A2.13.3

energy, 2.1.3, A2.I3.5

entropy, 2.1.3 farad, 2.1.3, A2.13.1

feature, Al.l

figure (numerical), Al.l

force, 2.1.3, 3.4.1, A2.13.6

frequency, 2.1.3 henry, 2.1.3, A2.13.2

illumination, 2. 1 .3 hertz, 2.1.3

joule, 2.1.3, A2.13.5

kelvin, 2.1.1, A2.I2.5

kilogram, 2.1.1, A2.12.2

length, 2.1.1, A2. 12.

liter, 2.1.3, A2.I1.1 lumen, 2.1.3, A2. 13.9 luminance, 2.1.3

luminous flux, 2.1.3, A2.I3.9 luminous intensity, 2.1,1, A2.12.6

lux, 2.1.3 magnetic field strength, 2.1.3 magnetic flux, 2.1.3, A2.13.IO

magnetic flux density, 2.1.3, A2.13.II magnetomotive force, 2.1.3 mass, 2.1.1, 3.4.1, A2.I2.2

meter, 2.1.1, A2.12.I

metrication, A 1.1 metricize, Al.l

mole, 2.1 .1 • newton, 2.1.3, A2.13.6

nominal, Al.l ohm, 2.1.3, A2.13.4

plane angle, 2.1.2, A2. 12.7 ' h

power, 2.1.3, A2.I3.12 . , : , precision, Al.l

pressure, 2.1.3, 3.4.6 quantity of electricity, 2.1.3, A2. 13. 13 quantity of heat, 2.1.3 radian, 2.1.2, A2.I2.7

radiant intensity, 2. 1 .3 rationalize, Al.l

second, 2.1.1, A2. 12.

significant, Al.l '

solid angle, 2.1.2, A2. 1 2.8

specific heat, 2. 1 .3 steradian, 2.1.2, A2.12.8

stress, 2.1.3, 3.4.6

tesia, 2.1.3, A2.13.il thermal conductivity, 2.1.3 thermodynamic temperature, 2.1.1, 3.4.3, A2.12.5

time, 2.1.1, 3.4.4, A2.13.3

tolerance, Al.l

U.S. customary units, Al.l

velocity, 2.1.3

viscosity, dynamic, 2.1.3
APPENDIX III 181

viscosity, kinematic, 2,1.3

volt, 2.1.3, A2.13.3

voltage, 2. 1 .3 volume, 2. 1 .3

iSIh E 380

watt, 2.1.3, A2.13.12 wavenumber, 2.1.3 weber, 2.1.3, A2.13.10

work, 2.1.3

TABLE 1 Rounding of Minimum and Maximum

Limits Note—The table can be extended on the same basis m either direction as the need arises. Use of the table

will result in maximum differences of 1 percent be- tween the actual and rounded values.

Numerical Range —^———— ^— Round to Nearest from but less than

0.005 0.025 0.0001 0.025 0.05 0.0005

0.05 0.25 0.001 0.25 0.5 0.005

0.5 2.5 0.01 2.5 5 0.05

5" 25 0.

1

25 50 0.5 50 250 1 250 500 5 500 2 500 10 2 500 5 000 50

5 000 25 000 100

25 000 50 000 500

50 000 250 000 I 000

TABLE 2 Inch-Millimeter Equivalents Note—All values in this table are exact, based on the relation 1 in. = 25.4 mm. By manipulation of the decimal point any decimal value or multiple of an inch may be converted to its exact equivalent in millimeters.

in. 0123456789 mm

0 25 4 50.8 76 2 101 6 127 0 152 4 177.8 203 2 228.6

10 254 0 279 4 304.8 330 2 355 6 381 0 406 4 431 .8 457 2 482.6

20 508 0 533 4 558.8 584 2 609 6 63^5 0 660 4 685.8 711 2 736.6

30 762 0 787 4 812.8 838 2 863 6 889 0 914 4 939.8 965 2 990.6 40 1016 0 1041 4 1066.8 1092 2 1117 6 1143 0 1168 4 1193.8 1219 2 1244.6

50 1270 0 1295 4 1320.8 1346 2 1371 6 1397 0 1422 4 1447.8 1473 2 1498.6

60 1524 0 1549 4 1574.8 1600 2 1625 6 1651 0 1676 4 1701 .8 1727 2 1752.6 70 1778 0 1803 4 1828.8 1854 2 1879 6 1905 0 1930 4 1955.8 1981 2 2006.6

80 2032 0 2057 4 2082.8 2108 2 2133 6 2159 0 2184 4 2209.8 2235 2 2260.6

90 2286 0 231

1

4 2336.8 2362 2 2387 6 2413 0 2438 4 2463.8 2489 2 2514.6

100 2540.0
182 ENGINEERING STANDARDS

E 380

TABLE 3 Inch-Millimeter Equivalents of Decimal and Common Fractions From to 1 in.

Inch '4's '/4's 8ths 16ths 32nds 64ths Millimeters °ani)fch°^

1 0.397 0.051 625

1 2 0.794 0.031 25 A C\A(k. (?7S U . U4D 0 /

1 2 4 1 588 0.062 5

5 1 984 0.078 125

? 6 2 381 0.093 75

•7

2 4 8 3, 175° 0.125 0

9 3 . 572 0. 140 625

5 10 3 969 0. 156 25

1

4 300 A 171 07 ^ 6 12 4,762 0.187 5

13 5. 159 0.203 125

7 14 5.556 0.218 75

1 ^ J , V J J 4 8 16 6 350° 0.250 0

17 6 747 0.265 625

9 18 7 144 0.281 25

1 Q 7 I nU

90/=; ft7S . Z70 o /

5 10 20 7 938 0.312 5

21 8 . 334 0.328 125

1 1 22 8.731 0.343 75

Q 1 7W A -ICQ -57 C 6 12 24 9 525" 0.375 0

25 9,922 0.390 625

26 10.319 0.406 25

1 1 in 7 1 A 1 U . /ID A A')] C7S

7 14 28 11112 0.437 5

29 11 . 509 0.453 125

15 30 1 1 .906 0.468 75

31 1 2 . 303 n '10/1 n^

8 16 32 12.700" 0 500 0

33 13-097 0.515 625

17 34 13.494 0.531 25 35 13 . 891 0 . 546 8/5

9 18 36 14.288 0.562 5

37 14.684 0.578 125

19 38 15.081 0.593 75 39 15.478 0 609 375

10 20 40 15,875" 0.625 0

41 16.272 0 640 625

21 42 16.669 0.656 25 43 17.066 0.671 875

11 22 44 17.462 0.687 5

45 17,859 0.703 125 23 46 18.256 0.718 75 47 18.653 0.734 375

12 24 48 19.050° 0.750 0

49 19.447 0.765 625

25 50 19.844 0.781 25

51 20.241 0.796 875

13 26 52 20.638 0.812 5
APPENDIX III 183

<lSlb E 380

TABLE i—Continued

Inch Wt '/*'» 8thi 16tbs 32nds 64ths Millimeten

53 21.034 0.828 125 27 54 21.431 0.843 75

55 21.828 0.859 375

14 28 56 22.225° 0.875 0

57 22.622 0.890 625 29 58 23.019 0.906 25

59 23.416 0.921 875

15 30 60 23.812 0.937 5

61 24.209 0.953 125

31 62 24.606 0.968 75

63 25.003 0.984 375

16 32 64 25.400° 1.000 0

° Exact. TABLE 4 Rounding Tolerances

Inches to Millimeiers

Original Tolerance, in _. , Fineness of

at least less than Rounding, mm

0.000 01 0.000 1 0.000 01 0.000 1 0.001 0.000 1 0.001 0.01 0.001

0.01 0 1 0.01

0.1 1 0 1

TABLE 5 Conversion of Temperature Tolerance Requirements

Tolerance, deg F ±1 ±2 ±5 ±10 ±15 ±20 ±25

Tolerance, K or deg

C ±0 5 ±11 ±1 ±5.5 ±8 ±11 ±14
184 ENGINEERING STANDARDS

*lSlb E 380

S 3

0 jz % *

1 -I 2

0. 1/}

-o 2

u u

J= " ^ Z

o

.2

a. _

^, O

6

._ c £

i2 5

<S n - 1 i J 3 3 o a- i «J ._: i

c =.E

« 2 „ ; 5 Jo ~ ^ •i o ^ ' o ^ :

(/) x» — ' 1« i»l to ' u ^ .E I

5/3 ^ . O >. O

C CO _ I « C C I t:u -c J 3 S * J V 5 r-

• - E ^ Z 'ij « ] u - 5^

CO h- ^ i < O n i

— so rs| 00 m »0 O *^ — — o

*o — rr*-i O 0\ rt ^ 00 00

00 voO *N m ^

OO Ov

1^ OO

lO ^

f*^ ^ »0 ^

—

r*-i — OO

ry- ^ r^, 00 r- 1^

fN i

r^- rrf O OO

vO — W-1 r-j ^ Q rs) ^ — 2S8

00

\0 Q rj- NO

OO so ^ ON

OO OO

VI f*^

w-1 CT^

rsi r*-, — O O O r*-. Ov ^ vi

«-i — r-- CO \D O ~ \D

r*-i m fS ;3 s:

OO TT o m — OO

00 NO

rj- — OO

rv| r*i r*',

»0 — NO

r*^ fsj CnI

OS

rs OO

NO ^

m— o O

SnOno rr rs »o in ^

— O On —

rs| m r'.

r-- r*^ ON — On nO

rs| NO —

r*^ m

Wl O NO 3fS ON — *n

rs| —

r^- r*^ rsl m O r- rn

O NO —

1^ ^ rsj fs fN

»o

— O On ^ >0 <n

00

v~t _ r~ ON 1^ OO *^ 00

vo

NO »o

*^ On NO

rv| m

rs| CO rf- On rr*-t fs| vO »0 v-»

O»n lO

ON »n — ^ Or- ^ t

rs On On TT OO

QO OO rO ON OO

•"M 00 »n

rs| rst f*-,

VI O NO in rsi <^ OO r*-) r-- NO NO

r-- o "n

r-l On nO

TT ^ »o

rN 00 O r- v-i OO

v-> V-) O On 00

rs 00 vi

T^- m

r^i rN —

— OO »n ^ v-i

— r- OO V~i •nO ON

rsi OO

nO no

S8
APPENDIX III 185

<1S||1 E 380

^ - S;i OJ o ''^

O ^ «^ = 5^

.2 8g

j5 6 o;

E.9-

85— u O C

o U

I J= c

t — 1»

"1 *^

.Jr.

I -a o

u Z

CO \0 -rt OO 00 oo — rsi

m 0\ ^ in — c» ^ V"! vri OO ^r-- — rsi

^ O ^ \0 r<; 3 r-- r-^

00 Tj- 0\ r~A

V-) fS CTv ^ t/-i

rs| o OO oo oo r*- r*^ 'rf

(N

fNI ON

»o — oo

\0 r--

rNi o oo

r-. m ^ »n

S rsj ^ ^ — r- oo ON

oo OO

OO w-i ^ \0

vO fS

1^ r-- \D 00

2- ON ^ On lO fS O 1^ O — —

r-- »ri r--, «^ »o lO \0 oo

O On OO — O r-- fM

OO

On NO 3Sr--i — On

«/^ rr

w~i

OO r-j OO

FN ON »0

r*-) Ov \0

rsi r-j r*-)

r-- *o r*~i oo

oo rsj rs oo

r*-. ON ND

V-)

NO — NO NO 0\

fN 0^ "'^

rs| rs|

— Ov ^ rn m i/^

— so —

nO rs| On

<N ^ v-1

r- «i f--i NO r- 00

so — sO

«o ^ oo

rsi o^ u~t NO NO — On

r*-i r*i rs| ^ w-i

8S:

w-i m rsi fsi NO oo

— 00 »n 00 OO o*

rs| — ^ rsj —

r*-) tT i/^

oo 00 On «n — r- 'a- 00 00 Onoo f*^ rsi oo «o — r-- TT o o —

nD — NO

NO On o r-- oo 00 On

— O*

r*-i O rr

r^i so rs^ NO rs| o» 8r-.o —NO rg NO

VI rsj oo O rrvi r^^ On r-O O

oo NO

On Os OS

lo NO roo NO T:f oo 00 oo

W-) \o r--

CM O 00 oo

oo o^

<^^»n NOP-OO
ENGINEERING STANDARDS

E 380

- 1.6 N (MOON, TRANQUILITY BASE)

9.8 N (EARTH, SE^ LEVEL)

FIG. 1 Illustration of Difference Between Mass

(Unit = Kilogram) and Force (Unit = Newton).
APPENDIX IV

COMPATIBILITY OF SCREW THREADS

Equations are developed for determining the compatibility of comparable standards; i.e., standards sufficiently identical in thread profile such that compatibility can be achieved by scaling size.

A. General plan,

1. In this study, threads are considered to be compatible if mating parts,

such as a nut and a bolt

a. Fit together without interference over a sufficient length of threaded

segment as to be considered adequate. This length, called "length of

engagement" is usually considered adequate for general use if it equals 1 1/2 diameters.'

b. Fit together with sufficient overlap of material of internal and external thread as to insure strength of coupling and with sufficient binding or friction as to resist loosening due to vibration, etc.

2. Given the nominal profile of the thread, which can be defined by

dimensionless quantities, the considerations above lead to the establishment

of minimum and maximum values for the dimensions of various thread ele- ments such as

a. Major diameter (that diameter measured at the crests of the external

thread and the roots of the internal thread).

b. Minor diameter (that diameter measured at the roots of the external

thread and at the crest of the internal thread).

c. The pitch diameter (see A. 4 below).

3. Thus, in evaluating the compatibility of external with internal thread one has knowledge of the dimensions of the maximum profile of the thread

beyond which material cannot exist if interference is to be avoided and also

minimum profile which must be filled with material if the threaded coupling

is to serve its function. It is the practice of thread standards to give as "basic

values" those dimensions of thread elements that define the maximum

profile and to specify as tolerance and allowance, departures from basic

values that define minimum profile. Although the sum of tolerance and al- lowance defines the minimum profile (of importance to the study) allowance

is usually specified separately to insure a minimum clearance for some

classes of threads to facilitate ease of assembly or to provide for plated

finishes or other coatings. In this survey for compatibility the sum of the

tolerance and allowance values will be considered significant. In other

words, one thread will be considered equivalent to another thread if basic

values of the elements of one thread fall between the maximum and

minimum profile of the other.

• Handbook H28 (1969) pt. 1, sec. 2, par. 7, p. 2.21.

422-764 OL - 71 - 13 187
188 ENGINEERING STANDARDS

4. In comparing threads of the same shape, but of different dimensions,

the similarity of pitch diarrieter is most critical and implicitly provides limita- tion on the differences in pitch that can be tolerated between two dissimilar

threads.

a. In general, standards specify significantly smaller magnitude of

tolerance on pitch diameter than they do for major or minor diameters. Dissimilar threads that can be adjusted to fit utilizing pitch

diameter tolerances can also be adjusted to fit at root and crest utiliz- ing major and minor diameter tolerances.

b. There are two aspects of pitch diameter — a geometrical aspect and

a functional aspect. The geometrical pitch diameter (called "pitch

diameter" or "simple pitch diameter") is the diameter of that imaginary cylinder whose surface would pass through a straight thread in such a manner as to make the widths of the thread ridges and the

thread groove equal.

The functional pitch diameter (called the "virtual pitch diameter") is the pitch

diameter of the enveloping thread of perfect pitch, lead and fiank angles and

with specified length of engagement. It is derived by adding to the pitch

diameter in case of an external thread or subtracting from the pitch diameter

of an internal thread, the cumulative effects of deviations from perfect

profile, including variations in lead and flank angle over the specified length

of engagement.^ The cumulative effect due to deviation from perfect pitch is^

(±8P) Cot « THREAD APEX ANGLE

2

length of engagement (positive locking will occur),

the perfect pitch

the absolute value of deviation from perfect pitch,

deviation added to the pitch diameter in the case of external

threads and subtracted from the pitch diameter in case of internal

threads.

5. As tolerances on screw thread elements are meant to provide max- imum and minimum dimensions for screw thread profile, tolerances on pitch

diameter have the following relation to pitch diameter and to vertical pitch

diameter.

a. The maximum-material pitch diameter limits are a limitation on the

virtual pitch diameter.^

b. The minimum-material pitch diameter limits are a limitation on the

pitch diameter.^

2 Handbook H28 (1969) pt. l,sec. 1, par. 6.21, p. 1.05,

3 Handbook H28 (1969) pt, l.sec, 1 , par, 6,24, p, 1.05.

* Handbook H28 ( 1 969) pt. 1 , sec, 2, par. 8.2, p. 2,22,

5 Handbook H28 ( 1 969) pt, 1 , sec, 2, par, 8, p, 2.2 1

where a =

i±8P) =

Pa =

\Pa-Pb\ = ^D=
APPENDIX IV 189

6. As pitch diameter tolerances are, in general, most critical and as the ef- fective pitch diameter (virtual) is a function of the geometrical pitch diameter, the difference in pitch between mating parts and the length of engagement, the general plan for assessment of the compatibility of threads of dif- ferent standards is to utilize these degrees of freedom to identify pitches and

pitch diameters that would be interchangeable with U.S. and International

Metric Standard Threads.

a. A fundamental requirement is that threads of different standards

have compatible shape; that is, that compatibility can be achieved by

modification of dimension rather than modification of shape.

b. Threads of U.S. and ISO Standards that have compatible shape all provide for a thread apex angle of 60 degrees. Therefore, the equation of A.4.b reduces to AD={±dP) 1.732051.

B. Deflning a screw thread that is interchangeable in pitch diameter with a

U.S. Thread and an ISO Metric Thread.

1. The pitch and pitch diameter of the external thread must be chosen

such that the virtual pitch diameter equals the basic pitch diameter of the in- ternal thread as specified in either the U.S. Standard or the ISO Metric

Standard.

D, = Di- 1.732051 Lei|l -Pe/Pi| = Z)2 - 1.732051 Le2\l-PelP2\ (I)

De = the basic pitch diameter of the proposed external thread

Pe=the pitch of the proposed external thread

Di = the basic pitch diameter of the U.S. internal thread^

Pi = the pitch of the U.S. internal thread** D2 = the basic pitch diameter of the ISO internal thread ^ P2 = the pitch of the ISO internal thread ^

Lei = the maximum length of engagement when coupled with a U.S. internal

thread. As locking will occur at this length, it must equal or exceed

length of engagement required of US threads for normal usage; i.e., approximately 1.5 Di.

Le2 = the maximum length of engagement when coupled with a ISO internal

thread. As locking will occur at this length, it must equal or exceed

length of engagement required of ISO threads for normal usage; i.e., approximately 1.5 D2.

2. The pitch and pitch diameter of the internal thread must be chosen such

that the virtual pitch diameter equals the basic pitch diameter of the external

thread as specified in either the U.S. Standard or the ISO Metric Standard.

D„ = Dil.732051Lei[l -P„//'i] = D2l.732051Lei[l -P„/P2] (2) Dn = The basic pitch diameter of the proposed internal thread

P„ = The pitch of the proposed internal thread

^ This value is the same for U.S. external and internal threads.

^ This value is the same for ISO external and internal threads.
190 ENGINEERING STANDARDS

3. From equations 1 and 2, expressions for Pz and P„ are derived. Pe

and Pn are limited to values between Pi and Pi.

Kl^el^L-et)^ 1.732051

Use {+) when P, < Po; P^^Pe^ P2

Use (-) when Pi > P^ P^^P,^ P^.

P1P2

LeiP1 + LeiP2

(3)

Pn (Lei + Le2)

P^P2

1.732051 J LeiPi + LeiP2 (4)

Use (-) when Pi < Fa; Pi ^ P« ^ ^2

Use (+) when Pi > P2; P2 ^ P« ^ Pi.

4. In equations 3 and 4, note that Pe and P„ are symmetrically distributed

about a value established by the quantity

(Lei + •Le2) LgzPi + LeiPa

Therefore, if derived values of Pe and P,, are not to be unduly biased in favor of Pi and Po, the maximum length of engagements. Lei and Le2, should

be selected such that

(Lei + Le2)

LelPi ~l~ LeiP2 2

or Le2lLei = P2IPi.

5. Minimum limits to values for Lei and Le2

a. If values of Pe and P„ are limited to fall between Pi and P2, then

ID1-D2I P1P2 IP1-P2I

1.732051 LezPi + LeiP. 2

b. Combining this requirement with the required ratio of Lgi and Le2 established above

= 1.732051 AP

^''^ = 1.732051 AP

where AD= |Di — D2I

AP=|Pi-P2|
APPENDIX IV 191

c. If these minimum values for length of engagement are sufficiently

large as to fulfill requirements of U.S. and ISO Standards, there is advantage in utilizing them in determining the pitch and pitch diameter of the proposed thread.

1 . Pe will equal Pi or Pi and Pn will equal Pz or Pi

2. De will equal D, or D2 and Dn will equal D, or Di

3. A manufacturer would need to modify only the external thread or

the internal thread, not both, in order to achieve a thread compatible with both the U.S. and ISO Metric Standard.

6. It should be noted that the proposed thread will in general have dif- ferent basic values for the pitch and the pitch diameter of external and inter- nal thread. Therefore, in coupling together, even perfect threads (made to the proposed dimensions) would have limited rather than infinite length of

engagement Le where

L=

^"-^^

(7) 1.732051 1 l-Pj/'nl

^

C. Limitations on De and D„

1. Equations (1) and (2) (sec. B) assure that the basic pitch diameters of

the proposed thread do not exceed maximum material values as specified in either the U.S. or ISO Metric Standard.

2. Equations (5) and (6) (sec. B) establish minimum values for length of

engagement Lei and Le2.

3. Therefore, except for the case noted in section B.5.C, the basic pitch

diameters of the proposed thread will not meet maximum material conditions

as specified in either the U.S. or ISO Metric Standard. The greater the

values of Lei and Le-i, the closer the basic pitch diameters will move to minimum material conditions as specified in the U.S. or ISO Metric Standard. This implies the existence of maximum limits for Lei and Leo.

4. To circumvent disagreements as to whether the proposed threads will couple with threads of existing U.S. and ISO Standards with sufficient precision as to provide functional adequacy, differences in pitch diameters of the

proposed thread and present standard threads are limited to values approximately equal to or less than the tolerances for pitch diameter specified in existing standards.

5. Whereas tolerances established for maximum material limits are rigorously applied to avoid interference in coupling external with internal

thread, it appears that standard practice provides more leniency in application of tolerances that establish minimum material limits.'^ Therefore, in the

development of equations in this section some lack of rigor will be allowed

so as to serve the purposes of an overall survey for potential compatibility of

threads.

6. If De and D„ are to meet the requirements for minimum material conditions, then

« Handbook H28 ( 1969) pt. 1 , sec. 2, par. 8, p. 2.2 1

.
192 ENGINEERING STANDARDS

De^D,-A

De^D^-B

Dn^Di + C

Dn^Dz + D

where

A = External thread tolerance plus allowance for pitch diameter as specified in the U.S. Standard.

B = External thread tolerance plus allowance for pitch diameter as specified in the ISO Metric Standard.

C = Internal thread tolerance for pitch diameter as specified in the U.S.

Standard.

D = Internal thread tolerance for pitch diameter as specified in the ISO

Metric Standard.

a. A necessary condition-' for the quantity (D„ — D^) is Dn-De^A + C For A + C < B D

D„-De^B + D ForA + OBD.

b. Substituting for D„ and De using eqs 1 and 2 and utilizing the rela- tion LeiP\=^ LezPt (see section B4)

1.732051

^

^''=

1.732051 '^P

^

where A/'^ -P2I

and A'= {A-\-C) or (B + D) whichever is smaller.

7. Limiting condition for the absolute magnitude of Di — Di Equating ; eq 8 with eq 5 or eq 9 with eq 6, provides a maximum limit for AD

AD= ID1-D2I (10)

8. Limiting condition for the absolute magnitude of Pi — Pi

a. Equations (8) and (9) indicate that the maximum limit for AP,

depends upon the ratio of PjL.

b. The value, L, is the length of engagement at which positive locking

will occur. Thus, L must be at least equal to the length of engagement specified by U.S. and international standards. This implies

limits on the value of Af.

c. The ratio between pitch and required length of engagement will vary

among standards but for threads having general application it usually

This condition is not sufficient in itself because it ignores differences between £>, and D2.
APPENDIX IV 193

follows some function of the major diameter of the thread.'"

Therefore, for the purposes of this survey, eqs (8) and (9) are added

to yield

D. Utilization of the equations in surveying the compatibility of thread series having compatible profile but dissimilar dimensions.

1. The ratio of pitch to required length of engagement is estimated for each thread series. Generally this ratio will roughly follow a linear function

of diameter.

2. The values of pitch diameter tolerances (the sum of external and inter- nal tolerance and allowance) are estimated for each thread series. This value

usually increases with diameter.

3. These estimates are used to derive a limiting value for pitch difference

using eq (11). The pitches of the two thread series are then compared rela- tive to this limit. As threads series specifying hundreds of threads generally

utilize a relatively small number of pitch values, large thread series can be

quickly surveyed for potential compatibility.

4. For those threads of each series having sufficiently similar pitch values,

the pitch diameters are compared relative to limiting values established using

eq(lO).

5. For those threads of each series that pass the test for pitch and pitch

diameter similarity, calculations are made using eqs (3, 4, 1, 2). These calculations provide basic values for pitch diameters and pitches of external and

internal threads that are interchangeable with the threads of the two series

being considered. In selecting values for the length of engagement used in these equations, the minimum values required are determined using eqs (5) and (6). If these lengths are greater than that required for the thread series

under consideration, these values are used as this minimizes the need for modification. If these minimum values are smaller than those required to meet length of engagements required by the standards, the standard length

of engagement is used in the equations, modified only to the extent of maintaining the relafion Le-i P-2 = Lei Pi. However, lengths of engagement

may not exceed values defined by eqs (8) and (9).

E. Advantages and disadvantages of the proposed thread.

1. The proposed thread will be interchangeable with both the U.S. Standard and the ISO Metric Standard and will in itself function as a system.

a. A screw thread manufacturer can convert to the proposed system at his discretion, knowing that the conversion will be interchangeable

with his past production.

b. It will be advantageous for the manufacturer to convert in the sense

that the proposed system will be compatible with both U.S. and ISO

Metric Standard threads.

P=\Pi- P-i] ^ X r p

2-1.732051 L,

ISO Recommendation 965/1. sec. 12.2. p. 19.
194 ENGINEERING STANDARDS

2. As the general approach is to utihze a portion of the present tolerances

to derive basic values for a new system that is compatible with both U.S. and

ISO Metric Standards, it follows that deterioration of functional per- formance (at least theoretically) can only be avoided if present tolerances are reduced in the proposed system. Even with such reduced tolerances functional performance cannot be as optimum as is sometimes achieved by

threads of the present standards.
APPENDIX V

First Progress Report, January 5, 1971

APPENDIX V

A Saidy to Develop an Optimum Metric Fastener System

ENGINEERING

REPORT:

This report is included with permission of the

Industrial Fasteners Institute.

Industrial Fasteners Institute 1505 East Ohio Building 1717 E. 9th Street Cleveland, Ohio 44114 USA

© Industrial Fasteners Institute 1971

195
196 ENGINEERING STANDARDS

FOREWORD

The Industrial Fasteners Institute is an association of

leading American and Canadian manufacturers of bolts, nuts,

screws, rivets, and all types of special industrial fasteners. IFI member companies combine their technical knowledge to advance the technology and application engineering

of fasteners through planned programs of research and

education. The Institute and its member companies work

closely with leading national and international technical

organizations in developing fastener standards and other

technical practices.

On May 20, 1970, the IFI Governing Board met to establish a policy position relative to metric. Part of that policy

states

"Industrial Fasteners Institute recognizes

that important segments of American Industry

may elect to convert to metric. In such

event, the IFI position is that a new system

of standard fasteners designed for optimum

performance capability should be developed

and stated in metric units.

The new system would be a complete "fresh

start" approach not necessarily related to

any existing system. The purpose would be

to achieve optimum performance capability in

the use of all materials used in the fastening function and to attain maximum simplification in the number and styles of standard

fasteners .

The Board then instructed its two principal technical com- mittees - Standards and Technical Practices Committee and

the Engineering Committee on Small Screws - to initiate a priority program of study and research. First discussions

were held at a joint meeting in mid-June , and a carefully

selected Task Group on Fastener Design and Simplification

was appointed. (Annex F) Since that time, the Task Group

has met several times, and has completed a massive program

of work as outlined in this report. The results of this

i effort led to the development of a recommended series of

sizes, thread pitches, and a basic thread form for a series

of metric module fasteners.

The technical content of this report was reviewed at a joint

meeting of the two technical committees on December 16, 1970

and the recommendations presented herein received their

endorsement.
APPENDIX V 197

A STUDY TO DEVELOP AN OPTIMUM METRIC FASTENER SYSTEM

INTRODUCTION

Most large USA corporations are internationally based with

significant financial and manufacturing commitments located

in other countries of the world. While all of these corporations still use customary inch/pound units as the principal

engineering and production base for their domestic operations,

the world markets they serve have obligated design of many

products in conformance with engineering standards and units

of measurement other than those commonly used in USA. VJorldwide interchangeability of assemblies and their component parts

has been sacrificed to accommodate those systems of standards

and systems of measuring units common to the country of manufacturing origin or prime consuming market.

During recent years many corporations have been studying means

for reducing or eliminating the cost of supporting two or more

systems of engineering practices. Some are already planning

a unification of their corporate engineering standards into a single system to be used by all their facilities, both domestic and foreign.

In August 1968, the 90th Congress of USA passed Public Law

90-472. This act instructs the Secretary of Commerce to

conduct a comprehensive program of investigation to determine

the impact on the United States of the increasing worldwide

usage of the metric system of measurement. It further

instructs the Secretary to return to Congress within a three

year period to outline the findings of the study and present

recommendations on what actions USA should take.

The metric study, which has now been under way for over two

years , has sharply focused management attention upon the

potential values inherent in the development of engineering
198 ENGINEERING STANDARDS

Standards which would be truly international in recognition and

acceptance, and attendant with such a system, a single measuring practice. Realistically, although the great burden and

expense of change would fall on USA, the only system of measuring units with any chance of worldwide acceptance is the

International System of Units.

The International Organization for Standardization (ISO) is a federation of national standardization bodies representing

about 60 countries of the world. The first two technical

activities authorized by ISO, shortly after it was formed in

1946, concerned screw threads and threaded fasteners. ISO/TCI

on screw threads and IS0/TC2 on threaded fasteners each have

held numerous meetings, progress has been excellent, many projects have been completed, and several ISO Recommendations

published. However, TCI, and particularly TC2, have years of

work ahead before documents will be available permitting the

selection and manufacture of thre^ided fasteners completely from

ISO standards.

The fastener manufacturing industry supplies to all other

industries standard and special bolts, screws, nuts and other

threaded pa-^ts used in joining the component parts of engineered assemblies. Observing the growing interest in metric by

many important USA corporations, it has become increasingly

evident to the USA fastener manufacturing industry that within

the near future it will be asked to produce and market a system

of metric fasteners. The industry is willing to meet its . . responsibilities.

However, before any metric module fasteners can be manufactured, engineering documentation must be made available. It does

not now exist. Because of the incompleteness of ISO documents,

and because no other single system of national standards has

international acceptance, it is apparent that new documents

must be prepared. Such documents will probably be a mixture

of copying from existing ISO standards, adapting from current

domestic practices, and creation of new material as necessary
APPENDIX V 199

to properly specify all requirements.

A question of prime importance concerns the level of technical

sophistication of ISO documents for metric fasteners and the

national standards of metric countries compared to USA based

standards (ANSI, ASTM, SAE , IFI , etc.) for inch series products. Do the metric based fastener standards now in current

use equate favorably in performance capability, mechanical

properties, and quality assurance to those with which American

industry is now accustomed? Would present legal statutes and

regulations controlling the manufacture and sale of several

consumer products permit levels of performance capability

lower than those now available?

A realistic evaluation of current metric documentation leads

to the conclusion that the inadequacy of their technical

requirements will necessitate development of an entirely new

system of engineering standards for metric module fasteners.

If it is accepted that new documentation must be prepared, it

logically follows that when preparing such documents, every

opportunity should be taken to improve the performance capabilities of fasteners through redesign. It also seems logical

that the number of sizes, grades, types, styles, and series be

limited to the fewest possible number consistent with providing

an adequate system of fasteners to properly accommodate the

engineering requirements of the majority of industrial applications .

THE PROJECT

In May 1970, Industrial Fasteners Institute authorized the

project - A Study to Design an Optimum Metric Fastener System.

Its object is -
200 ENGINEERING STANDARDS

To develop a system of threaded fasteners,

to be stated in metric units of measurement, to incorporate into the design of

each fastener technical refinements con- tributing to improvement in performance

capability, and to simplify to the absolute degree possible the number of items

recognized as standard in the system.

OBJECTIVES -

. , -

There are four objectives -

technical improvement

simplification

cost reduction

realism

In the development of a system of threaded fasteners, the performance capability of each item, as it will be used in its

service application, should equal or surpass that which is now

offered by any similar fastener standard within any existing

system. Consequently, a prime objective is introduction of

technical improvement to attain superior performance capability.

Addition of unnecessary parts to a system is equally expensive

to the user as it is to the producer. An over-proliferation

of standard parts is confusing to designers and greatly com- plicates the problems of those responsible for procurement.

There are tremendous opportunities for simplification of

standard fasteners in terms of numbers of sizes, grades, types,

styles, and series. An objective of the program is to explore

and exploit these opportunities fully.

While important cost reductions may logically be expected from

improved design of fasteners through optimum use of materials
APPENDIX V 201

and improved mechanical and performance properties, the savings

realized through simplification can be considerable. By exer- cising strict discipline throughout the development of a new

system, immediate cost savings will be experienced when the

system is first introduced, and will compound indefinitely.

For any system of threaded fasteners to be acceptable domestically, it must be attractive internationally. The advantages

offered by a new system to any corporation interested in planning unification of its engineering standards must be compelling enough to encourage it to absorb modest change in its

foreign based operations v/hile simultaneously making the much

more extensive and costly conversion domestically. Consequently, the system must be realistic in terms of existing

standards and practices of other industrialized countries. A

major objective is to maximize the advantages offered to USA

corporations in their domestic operations, while minimizing the

inconvenience caused to their foreign based operations.

CONDUCT OF PROJECT

The total program logically divides into four separate phases -

I - Determination of a series of basic

diameters, thread pitches, and a thread form.

II Dimensional design of various families

of mechanical fasteners built around

the sizes accepted in Phase I.

Ill - Determination of mechanical properties

and performance capabilities of products

designed in Phase II.
202 ENGINEERING STANDARDS

IV - A study of related parts such as rivets, washers, pins, etc., and

application data such as grip

ranges, hole sizes, clearances,

drive systems, etc.

This report covers Phase I. It outlines the work done, the

data developed, and the conclusions reached. The completion

of Phase I is as far as the program can progress until fastener

users and producers have had full opportunity to evaluate the

merits of the Phase I recommendations. They are also invited

to consider the long range objectives of the total program, . ., and determine if there is sufficient value to their own personal and corporate interests, both domestically and internationally, to warrant support and active participation in the

conduct of Phases II, III, and IV.
APPENDIX V 203

A STUDY TO DEVELOP AN OPTIMUM METRIC FASTENER SYSTEM

SECTION A - SCOPE

The scope of Phase I is -

- to evaluate the current metric and inch

diameter/pitch series and thread form for

standard threaded fasteners, to learn their

merits, deficiencies, and possibilities for

technical improvement.

- to develop through analytical research and

experience an optimum diameter/pitch series,

to be stated in metric units , which would

offer designers using threaded fasteners an adequate selection of sizes to properly

accommodate commercial and industrial applications .

- in the development of the series, to critically

examine thread form and introduce technical

refinements contributing to improved performance

capability of threaded fasteners.

SUMMARY OF RECOMMENDATIONS

The recommendation of this study is that a new metric diameter/

pitch series for threaded fasteners be introduced. Its

principal features would be -

1. That there be only one thread pitch series.

2. That there be 25 sizes in the series through the

size range of 1 mm to 100 mm.

422-764 OL - 71 - 14
204 ENGINEERING STANDARDS

3. That the 25 diameter/pitch combinations in the

series be -

1 X .25 3.15 X .65 10 X 1. 5 30 X 3. 5 64 X 6 1.25 X .3 4 X .8 12.5 X 1. 75 36 X 4 72 X 6 1.6 X .35 5 X .9 16 X 2 42 X 4. 5 80 X 6

2 X .45 6.3 X 1 20 X 2. 5 48 X 5 90 X 6 2.5 X .55 8 X 1.25 25 X 3 56 X 5. 5 100 X 6

4. That the diameter/pitch combinations for sizes larger

than 100 mm be the "first choice" series for ISO

general purpose metric screw threads, ISO R261.

5. That the thread form for the series be the basic ISO

thread form, ISO R68, with two modifications,

a) the root of the external thread be radiused

within the limits of 0.150 P and 0.180 P,

where P equals thread pitch.

b) the addendum of the internal thread be

reduced to 0.1875 H, where H equals the

height of the fundamental thread triangle.
APPENDIX V 205

SECTION B - EVALUATION OF CURRENT THREAD SERIES STANDARDS

The evaluation of the current ISO metric and inch coarse

and fine thread series is separated into two parts - an analytical study and an appreciation of the lessons

learned through years of use experience.

Analytical Evaluation • /

Annex E-1 gives the metric diameter/pitch combinations

recognized as standard in ISO Recommendation R261. In the

size range of 1 thru 100 mm, 25 sizes are listed as first

choice, 19 as second choice, and 22 as third choice for a total of 66 sizes. Not all sizes are used for threaded

fasteners, and consequently, a more meaningful guide to

which sizes are considered standard for metric fasteners

is a study of published ISO Recommendations and national

standards of metric countries. Typical is R272 (Annex C)

which outlines the size series standard for metric hexagon

bolts, screws and nuts. Other documents for machine

screws and socket screws follow a similar pattern. Rarely

do they differentiate between sizes as being first, second

or third choice.

For the comparative purposes of this study, the metric size

series selected was made up of those sizes, in the range of

1 thru 100 mm, for which there are actual fastener standards

in ISO Recommendations.

The preponderant majority of all fasteners are produced

with either coarse or fine threads. The uniform pitch

thread series are infrequently used for standard products,

and consequently, the study was limited to just the two

thread series, coarse and fine (UNC and UNF in inch series,

coarse and preferred fine in metric series)

.
206 ENGINEERING STANDARDS

Fig 1 details the metric series of sizes and thread pitches

studied in this program. There are 43 coarse thread sizes,

12 are smaller than 6 mm (0.236 in.), 8 are between 6 and

18 mm (0.709 in.), and 23 are larger than 18 mm. In the

fine thread series there are 14 sizes, 6 between 8 and 18 mm,

and 8 larger than 18 mm. In the size range of 1 thru 100 mm,

there is a total of 43 sizes and 57 standard diameter/pitch

combinations for metric threaded fasteners.

Computer analyses of these ISO metric coarse and fine thread

series are given in Annexes B-1 and B-3, respectively.

Annex E-3 gives the inch series diameter/pitch combinations

recognized as standard in ISO Recommendation R263. The

smallest size is No. 0 (0.060 in. /I. 524 mm), however, to be

directly comparable to the size range of the metric series,

the two fine thread diameter/pitch combinations No. 00 - 96

(0.047 in. /I. 194 mm) and No. 000 - 120 (0.034 in. /O. 864 mm)

have been included. In the size range of No. 000 thru 4 in.

(101.6 mm) there are 33 primary sizes and 22 secondary sizes

for a total of 55. However, similarly to the establishment

of the metric series of sizes to be studied, only those inch

series sizes, coarse and fine threads, applicable to standard

fasteners were included.

Fig. 1 details the inch series of sizes for coarse and fine

thread series. There are 33 coarse thread sizes, 9 snaller

than 6 mm, 7 between 6 and 18 mm, and 17 larger than 18 mm. In the fine thread series there are 26 sizes, 12 smaller

than 6 mm, 7 between 6 and 18 mm, and 7 larger than 18 mm. In the size range of No. 000 thru 4 in. there is a total of

36 sizes and 59 standard diameter/oitch combinations for

threaded fasteners.

Computer analyses of these ISO inch coarse and fine thread

series are given in Annexes B-2 and B-3, respectively.
APPENDIX V 207

Observations

A study of the graphical presentations of metric and inch

diameter/pitch combinations in Figs. 1 thru 5 and the data

given in Annex B leads to certain observations.

a) There are too many sizes and too many diameter/pitch

combinations in both the metric and inch series. (Fig. 1)

b) The metric coarse series has too many large diameter

sizes, the inch series has too many small size diameter/

pitch combinations. (Metric fine thread series does

not extend below 8 mm.

)

c) Ratios of load carrying capacities between adjacent

sizes (RF = stress area of a size divided by the stress

area of the next smaller size in the series) are extremely erratic for all four series. (Fig. 3)

d) The ratios of areas (RA = stress area (SA) x 100% divided

by the area of basic diameter) follow similar patterns,

ascending as size increases. (Fig. 4). RA for metric

coarse is generally higher than for equivalent sizes in

the inch coarse series, and appreciably higher for small

sizes, in fact, it is surprisingly close to inch fine.

(RA is a measure of the coarseness or fineness of thread

pitch; for a given diameter, the higher the RA the finer

the pitch.

)

e) Stress concentration factors (SCF) follow a similar

pattern for all series. (Fig. 5). (NOTE: when computing

SCF, the root radius of the thread was assumed to be

0.144 times the thread pitch which is the maximum root

radius permissible for ISO inch and metric threads. In

actual production of threaded fasteners, root radius would

normally be somewhat less which would then increase SCF.)

For all series SCF generally increases as size increases.
208 ENGINEERING STANDARDS

Fine threads have substantially higher stress concentration

factors than coarse threads for equivalent basic diameters.

This indicates that, all else being equal, products with

coarse threads should exhibit a better fatigue behavior

than those with fine threads. SCF values for metric and

inch coarse threads are nearly identical.

Experience

The thread series introduced by Whitworth in the mid 19th

century serves as the basis for the present ISO inch coarse

thread series. The relatively coarse pitches selected at that

time were probably chosen as much for being those which lent

themselves to the production techniques of the day as for any

other single reason. As manufacturing skills improved and it

became economically feasible to produce threads to greater

degrees of accuracy, finer pitch thread series were introduced

and gained considerable popularity. Proponents pointed to

strength improvement and argued that finer threads have greater

resistance against loosening in service.

The debate on the respective advantages and disadvantages of

coarse and fine threads has continued ever since. It has

been an interesting exchange because no overwhelming support

has been generated for either series - a reasonably good

indication that merits and deficiencies are shared equally.

In recent years there has been a gradual gravitation toward

increased use of coarse threads. The motivation is probably

more closely aligned with simplification programs than for

purely technical reasons. This pattern of preference applies

to both inch and metric threads.

In the USA demand for fine thread small screws, (sizes smaller

than 1/4 in.) except for the No. 10 size, is practically non- existant. Fine thread sizes larger than 1 in. are rarely
APPENDIX V 209

used in commercial applications. Similarly, in Europe the

great preponderance of fastener production is coarse thread.

Many of the national standards of metric countries now actively

discourage selection of metric fine thread fasteners.

Although coarse threads are more popular, there is questionable

technical validity for a thread series to have thread pitches

as coarse as ISO inch. It would seem reasonable that a series

with thread pitches falling between the present inch coarse

and fine would be a technical improvement over both.

These observations led to the recommendation that there be only

one thread series.
ENGINEERING STANDARDS

SECTION C - DESIGN OF DIAMETER/PITCH SERIES

The most important service function of a fastener is to

transmit load. In this program first efforts were directed

toward a study of static load carrying capacities with a study of fatigue behavior following initial selection of the

most promising diameter/pitch series.

The six basic inter-dependent factors in the design of a series are -

basic diameter or size

thread pitch :

' basic thread form

stress area of threaded section

ratio of areas = —— x 100%

.7854 D

ratio of load carrying capacities between

adjacent sizes in the series = SA^j^.^^)

where I is the number of the size in the series.

D - Basic Diameter

D - P - TF - SA - RA -

RF -

Two important criteria are total number of sizes and the distribution of these sizes within the series. It has already

been pointed out that present metric and inch series have too

many sizes in the size range of 1 thru 100 mm. R261 recognizes

25 "first choice" metric sizes; in the comparable size range

of inch series fasteners there are 27 sizes which have a popularity of use far exceeding the remaining sizes. It seems reasonable that an optimum size series should not exceed 27

sizes, and should preferably be less.

Within the series the num±ier of sizes should be properly

distributed between those for small screws, generally smaller
APPENDIX V 211

than 6 mm, those in the range of 6 thru 18 mm where the great

preponderance of automotive, farm equipment, machinery, and

heavy appliance needs fall, and sizes larger than 18 mm as used in construction of buildings and bridges, heavy earth

moving equipment, ship building, railroads, etc. The

experience of present fastener usage indicates a reasonable

distribution in a 24 to 27 size series would be to include

not more than 8 sizes smaller than 6 mm and not less than 11

sizes larger than 18 mm.

P - Thread Pitch

Fig. 2 presents graphs of the current ISO metric and inch

coarse and fine diameter/pitch series.

In an optimum series, thread pitch, particularly since there

would ideally be only one thread series, should be no coarser

nor finer than existing ISO metric and inch coarse and fine

thread series.

TF - Thread Form

It would be extremely difficult, if not impossible, to

interest fastener users and manufacturers in any thread form

drastically different from the standard 60 deg thread of

ISO R68.

The long history of successful experience in using fasteners

with 60 deg threads is too extensive to permit serious

consideration of a major change without overwhelming masses

of research data, production of parts, and well documented

reports of their performance when actually used in a full

gamut of service conditions.

While thread designs different from the basic 60 deg form are being investigated at this time, evidence in support of a
212 ENGINEERING STANDARDS

total change is insufficient. Consequently, when designing

the diameter/pitch series, threads were assumed to be the

basic 60 deg form of ISO R68.

SA - Stress Area - ;

' '

Stress areas in this study were all computed using the standard

formula -

SA = 0.7854 (D - .9743 P)^

It is worth noting that as root radius increases, minor

diameter also increases and stress area becomes larger. One

of the final recommendations of this study is a thread form

modification to increase root radius (Section D) . It might

be useful to reconsider stress area formulation in Phase II

because any increase in stress area gives recognition to

greater load carrying capacities.

RA - Ratio of Areas

Ratio of areas is a useful parameter in the design of a diameter/pitch series. It is an indicator of the coarseness

or fineness of thread pitch, is a measure of thread efficiency

(how much of the load carrying cross sectional area remains

after threading) , and gives an indication of ease or difficulty

of thread assemblability

Fig. 4 is a plot of RA values for ISO metric and inch coarse

and fine threads as given in Annex B. An interesting

observation is that RA values for metric coarse sizes 7 mm

and smaller are surprisingly close to inch fine. Also, it is

noted that RA values for metric coarse sizes 8 mm and larger

generally fall between those for inch coarse and fine.

A first obvious approach is to design a series having a constant RA for all sizes. A reasonable value might be the
APPENDIX V 213

mean of the RA values of the existing series, say 75%. With

an RA equal to 75%, the thread pitch of the 100 mm size would

be 13.8 mm (1.8 tpi) , and for the 1 mm size would be .14 mm

(183 tpi). Both are quite impractical. The strength capacity

of large sizes in the series would be appreciably reduced, a waste of material; assembly problems when using small sizes

would be compounded, not to mention the great difficulty in

commercially producing screws with excessively small thread

pitches. Consequently, the practicalities of ease of assembly

and efficient use of material dictate a graduated progression

of RA. values increasing as size increases.

In the first trial runs to determine the most promising

diameter/pitch series, it was decided to maintain the same

set of RA values for each series. These values were arbitrarily chosen as grading from 65% for the smallest size

through 88% for the largest - roughly paralleling those of

the present series. It was understood that when the most

promising series were determined, refinements and adjustments

to RA values would be introduced.

RF - Ratio of Load Carrying Capacities

RF values for ISO metric and inch coarse and fine threads

are plotted on Fig. 3 from data given in Annex B.

The range for metric coarse is a high of 1.63 (the strength

ratio between' 2 and 1.6 irjn sizes) to a low of 1.11 (100 mm

over 95 mm). In metric fine the range varies between 1.56

and 1.14. For inch coarse the highest RF value is 1.65

(5/16 in. over 1/4 in.), and the lowest 1.14 (No. 6 over

No. 5). In inch fine the range is 2.03 to 1.20.

From a designer's standpoint, what is a reasonable increment

in load carrying ability between sizes? Should it be maintained as a constant percentage increase, or should size
214 ENGINEERING STANDARDS

effect be considered? In terms of real metal, to gain a strength increase of 25 percent over the 10 mm size would

require a diameter of only 11 mm; a strength increase of 25

percent over the 100 mm size would need a diameter of

1 0 9 . 6 mm

It seems wasteful to include sizes in a series that offer

strength increases of less than 20 to 25 percent over the

next smaller size. In the metric coarse series 23 of 42 RF

values are below 1.25. In the inch coarse series 13 of 32

RF values are less than 1.25.

If a constant strength increase of 75 percent between sizes was assumed, the next larger size in the series to the 1 mm

size would be 1.3 mm, to the 10 mm size would be 13 mm, and

to the 100 mm size would be 130 mm. In terms of metal, the

increase is reasonable for small sizes but becomes impractical

as size increases.

A rational approach in the design of a diameter/pitch series

would be to graduate RF values from relatively high values

for small sizes, and decrease RF as size increases. A minimum RF of about 1.25 is practical.

Design of Series

There are two basic approaches which were researched. The

first was to assume a series of sizes, and then knowing RA

(a series of set values was assumed) , compute SA, RF and P.

The second was to assume an RF load progression series, and

then knowing RA, compute SA, P and D.

In a "broad brush" exploratory study, seventeen different

series were put through the computer. Five were "diameter"

series, twelve were "load" series. (Annex A lists the

principal computer programs of the study.)
APPENDIX V 215

Most of these trial series were rejected for further study

as they grossly violated one or more of the predetermined

parameters. Some series had too many sizes, two had too

few, and others had a disproportionate distribution of sizes

within the three generalized size ranges. The three series

meeting the parameters best were -

1. A "diameter" series in which the sizes were

based on a combination of the R10/R20 preferred

number series. This series yielded 25 sizes

distributed 8, 5, and 12 in the three size

ranges

.

2. A "load" series in which RF was graduated as

a linear function from 1.75 to 1.25. This

yielded a 24 size series, distributed 7, 6 and 11.

3. A "load" series in which RF was varied in a geometric progression from 2.00 to 1.20. This

yielded 25 sizes, distributed 6, 5 and 14.

These three series were then investigated more thoroughly and

minor adjustments, primarily RA values, introduced.

It is well known that fine thread small screws have assemblability problems, both in terms of ease and time. Largely

for this reason USA demand for fine thread small screws is

practically non-existent. Reports from users of small size

metric screws indicate a similar experience - metric thread

pitches are too fine and cause assembly difficulties. As

experience in using inch series coarse thread small screws

has been quite good, it seems only reasonable that thread

pitches approaching those of inch coarse threads should be

acceptable in a new series. A small sacrifice in load

carrying capacity is a fair price to pay for ease of assembl-
216 ENGINEERING STANDARDS

ability. Consequently, an adjustment to RA values for sizes

smaller than 8 mm was made, reducing them from the original

"first trial" assumption to graduate evenly from 57% for the

1 mm size through 71% for the 8 mm size.

The results of these additional studies pointed out fairly

well the diameter/pitch series which fitted best within the

predetermined parameters.

The Ingredient of Reality

One conclusion of all the analytical research completed during

the course of this study is that it is virtually impossible

to design the ideal series, one in which all parameters are satisfied most favorably. The optimization of one criterion

forces sacrifice by one or more of the others. Consequently,

the final series must be a compromise, an attempt to gain the

most while giving up the least.

It is at this stage where the ingredient of reality must be

introduced. If the recommended diameter/pitch series was based on the best compromise of all technical data, every

size and thread pitch would be foreign to present standards.

Regardless of technical purity, the realities of present day

international involvements would seriously jeopardize acceptance, and more importantly actual use of such a series.

Consequently, when determining the final series to be recommended in this Phase I, the ISO standard metric coarse

thread diameter/pitch combinations exerted a strong influence.

In the recommended series, only those new sizes and different

thread pitches which are completely supportable by the

technical data generated in this study are included. The

remaining sizes and thread pitches in the series are continued

unchanged from the present ISO metric coarse thread series.
APPENDIX V 217

The Recommended Metric Diameter/Pitch Series

The "final" series resulting from all the studies is -

1 X . 25 6 . 3 X 1 42 4 ^ 1.25 X . 3 8 X 1.25 48 X 5 1.6 X . 35 10 X 1.5 56 X 5. 5

2 X . 45 12.5 X 1.75 64 X 6 2.5 X .55 16 X 2 72 X 6 3.15 X . 65 20 X 2.5 80 X 6

4 X . 8 25 X 3 90 X 6

5 X .9 30

36

X

X

3.5

4

100 X 6

Certain observations are in order.

a) There are 25 sizes in the series, 8 are smaller than

6 mm, 5 are between 6 and 18 mm, and 12 are larger

than 18 mm.

b) The sizes 1 thru 25 mm are in exact conformance with

the RIO preferred number series. The sizes 30 thru

100 mm are "first choice" sizes of ISO R261. Of the

15 sizes in the range 1 thru 25 mm, 10 sizes are "first choice" sizes of R261, 5 are new sizes.

c) Thread pitches conform with metric coarse thread

pitches given in R261 for all sizes except 2, 2.5,

4, and 5 mm and the five new sizes.

d) Fig. lA shows the 25 sizes in the series and their

relationship to the present metric size series.

It should be noted that each of the new sizes 1.25,

3.15, 6.3, 12.5 mm serves to replace two sizes in

the current series and the new 25 mm size replaces

three

.
218 ENGINEERING STANDARDS

e) Fig. 2A shows the diameter/pitch graph of the new

series. It falls within the extremes of those

for the current standards.

f) RF values for the new series are plotted on Fig. 3A.

It is immediately apparent that the RF curve of

the recommended series is a considerable improvement

over the very erratic plots of the current ISO metric

and inch thread series. RF values vary from a high

of 1.73 to a low of 1.25. Generally, through the

16 mm size RF is approximately 1.65 and for sizes

20 thru 100 mm RF decreases with reasonable uniformity

to 1.25.

Ideally the RF curve should be smooth but this would

be impossible unless diameters and/or thread pitches

were adjusted. Such adjustments would introduce

impractical values. As an example, the 16 mm size

appears inconsistent v/ith adjacent values. If thread

pitch was increased from the recommended 2 mm

(12.7 tpi) to 2.25 mm (11.3 tpi) RF values for sizes

16 mm with respect to 12.5 mm and 20 mm with respect

to 16 mm (now 1.69 and 1.56) would change to 1.64

and 1.62 respectively. The RF curve would smooth

out a little but at a sacrifice in the load carrying

capacity of the 16 mm size because its thread would

now be coarser and its stress area smaller. The

other apparent highs and lows of the RF curve can be

similarily rationalized.

As pointed out the new sizes "bridge" between existing

standard sizes and each makes it possible to eliminate

one or more sizes that otherwise would be required.

For example, the new 12.5 ran size bridges the 10 and

16 mm sizes. RF values for sizes 12.5 mm with respect

to 10 mm and 16 mm with respect to 12.5 mm are 1.60
APPENDIX V 219

and 1.69 respectively. If the 12 mm size which is

now standard in the metric series was retained and

the 14 mm size eliminated, RF values for sizes

12 mm with respect to 10 mm and 16 mm with respect

to 12 mm would be 1.45 and 1.82 respectively. An

82 percent increase in the load carrying capacity

between adjacent sizes at this important size

range of 10 thru 16 mm (0.394 thru 0.630 in.) is

excessive and would necessitate another intermediate

size

.

RA values for the new series are plotted on Fig. 4A.

The curve shows a considerable smoothing out of RA

values as compared to the existing metric and inch

thread series. It also shows the effect of the

thread pitch adjustments in the sizes 2 thru 5 mm. When studying this curve it is worth recalling that

as RA increases, thread pitch becomes finer and

stress area increases, however ease of assembly

decreases and manufacturing practicality may be

adversely affected. The recommended series yields

RA values that for all sizes in the series represent

reasonable compromises between these considerations.

It was this series that was investigated for its

fatigue behavior properties. (Section D) . The

conclusions of that study are that the recommended

thread pitches are valid.

422-764 OL - 71 - 15
220 ENGINEERING STANDARDS

SECTION D - FATIGUE BEHAVIOR

The majority of assemblies joined by mechanical fasteners

are subjected in some degree to dynamic loading during

their service life. Relatively few remain static and

totally insulated from some form of fluctuating stress,

vibration, stress reversal, or impact. However, only a small percentage of joints necessitate design where the

fatigue resistant properties of the fastener become the

primary design consideration.

Joints in which the rigidity of the joined material is less

than that of the fastener material; joints subjected to

stress reversal and loads which induce flexural stresses

in the fastener; and joints connected with fasteners having

low ductility properties are some of those in which the

dynamic load transmitting capability of the fastener is a matter of design importance.

In the design of an optimum metric series an objective should

be to improve the fatigue resistant properties of threaded

fasteners in every possible and practical way.

In Phase I of this study, potential improvement was limited

to thread design. While important, it should be noted that

fatigue property gains of considerably greater magnitude

can be obtained when designing actual fasteners in Phase II

and, secondarily through the processing techniques employed

during their manufacture.

The stress concentration factor of the thread, together with

a knowledge of the endurance limit and notch sensitivity

properties of the fastener material is needed to guide a designer in the proper selection of fasteners for a joint

subjected to known internal and externally applied forces.

Any reduction in the stress concentration factor of the
APPENDIX V 221

thread enhances the fatigue resistant properties of the

product.

The mathematical determination of stress concentration

factors (SCF) is extremely complicated. The method used

in this program is outlined in Annex D.

Using this method SCF values for ISO metric and inch

coarse and fine threads were computed and are given in

Annex B and are shown graphically in Fig. 5. It must

be pointed out that in these computations a root radius to

thread pitch ratio (RRPP) of .144 was used for all four

series. This is the maximum root radius possible with the

ISO basic thread form. In actual production root radius

would normally be less, and consequently, SCF would be

higher. Therefore, the SCF values given in Annex B and

shown on Fig. 5 are the optimum that could be expected for

the present ISO thread series.

Thread pitch, thread depth, minor diameter and root radius

are the dimensional elements influencing SCF. Minor diameter

and thread depth are functions of pitch, consequently, variations in either or both pitch and root radius will cause

variations in SCF.

When first studying SCF it was thought it would be advantageous to design a thread series with a constant SCF value

for all sizes. Unfortunately, this approach was proven

completely impractical. If RRPP is maintained constant at

.180 (equivalent to max root radius of UNJ thread form) to

attain a uniform SCF of 3.00 for all sizes in the 1 thru

100 mm series, the pitch of the 1 mm size would be .12 mm

(212 tpi) and for the 100 mm size would be 10.5 mm (2.4 tpi)

.

Similarly, if the presently specified pitches for metric

coarse are retained and root radius varied, to attain a constant SCF of 3.00, RRPP for the 1 mm size would be .12
222 ENGINEERING STANDARDS

and for the 100 mm size would be .22. While seeming to be

within reasonable limits, it should be pointed out that

with this approach, small sizes in the series would be

unnecessarily penalized by having root radii smaller than

are practical even though larger sizes may be advantaged.

Also, RRPP values exceeding .180 risk strength depreciations

between mating threads because of reduced thread engagement.

The great majority of fatigue applications occur in joints

using fasteners in the size range of 5 thru 30 mm (0.197

thru 1.181 in.). A second effort was made to learn the

possibility of designing a thread series with constant SCF

values for the sizes in this range, and varying SCF values

as necessary for larger and smaller sizes.

Annex D-5 presents two tables detailing thread pitches

for different SCF values and for RRPP values of .150 and

.180. The striking observation is the great difficulty

there would be to attain a uniform SCF just for these few

sizes without major adjustm.ents in thread pitches, either

making the pitch coarser as size increases, or finer as size decreases. Another point is the considerable effect

on thread pitch and/or SCF by changing RRPP from .150 to

.180. . , :

The stress concentration studies led to the following

conclusions -

a) it would be impractical to maintain constant

SCF values for all diameter/pitch combinations

in a series, or for a range of sizes within the

series.

b) RRPP should be held as a constant ratio for all

sizes
APPENDIX V 223

c) the only practical means for improving SCF values

through dimensioning is by increasing root radii.

Thread Form

The basic thread form as given in ISO R68 is standard for

both metric and inch series threads. Fig. 6 illustrates

this thread form with the one modification of showing the

root as radiused. Root radius limits of .108 to .144 of

thread pitch (UNR) are now standard for most USA commercially

produced fasteners. While root radius limits are not specified for ISO metric threads, it is a reasonable assumption

that the large majority of metric fasteners produced today

have radiused roots falling within the UNR limits.

Many years ago a modified thread form designated as UNJ was

introduced, and has since become the standard for aerospace

fasteners. It has also been used successfully with some commercial fasteners designed for use in selected industrial

applications

.

UNJ threads have more generous root radii than UNR. Because

of the large root (.180 P at max material limit), the minor

diameters of internal threads had to be increased slightly

to offset the theoretical possibility of mating thread interference during assembly. Despite the increase in minor

diameters of internal threads, thus reducing thread engagements (overlap of internal with external threads when

assembled) , the load carrying capacities of UNJ bolt-nut

assemblies are still in conformance with all specified

strength requirements.

Extensive research has proven that fasteners with UNJ threads

have improved fatigue resistant properties. The UNJ thread

form, now standard in USA, is being considered by ISO/TCI for

adoption as an international standard.
224 ENGINEERING STANDARDS

A thread form of the R68 basic form, but modified to

incorporate the proven advantages of UNJ, is entirely

practical. It is a recommendation of this study that

such a thread form be adopted for the new metric serie

This form is illustrated in Fiq. 6. The

two modifications in geometry are an increase in root

radius of external threads to be within the limits of

.150 to .180 P, and a reduction of the addendum of the

internal thread.
APPENDIX V 225

SECTION E - SUMMARY OF THE PHASE I RECOMMENDATIONS

The recommendation of this study is that a new metric

diameter/pitch series for threaded fasteners be introduced.

The principal features would be -

1. That there be only one thread pitch series.

2. That there be 25 sizes in the series through

the size range of 1 mm to 100 mm.

3. That the 25 diameter/pitch combinations (Annex B-4)

in the series be -

1 X .25 3.15 X

1.25 X .3 4 X

1.6 X .35 5 X

2 X .45 6.3 X

2 . 5 X . 55 8 X

.65 10 X 1.5

.8 12.5 X 1.75

.9 16 X 2

1 20 X 2.5

1.25 25 X 3

30 X 3.5 64 X 6 36 X 4 72 X 6 42 X 4.5 80 X 6 48 X 5 90 X 6 56 X 5.5 100 X 6

4. That the diameter/pitch combinations for sizes larger

than 100 mm be the "first choice" series for ISO

general purpose metric screw threads, ISO R261

(Annex E-2)

.

5. That the thread form for the series be the basic ISO

thread form (ISO R68) with two modifications,

a) the root of the external thread be radiused

within the limits of 0.150 P and 0.180 P, where

P equals thread pitch (rig. 6).

b) the addendum of the internal thread be reduced

to 0.1875 H, where H equals the height of the

fundamental thread triangle (Eig. 6).
226 ENGINEERING STANDARDS

ISO METRIC "^CH RECOMMENDED

FINE THREAD METRIC DIA/PITCH SERIES SERIES

COMPARISON OF NUMBER DIA/PITCH COMBINATIONS

000-120
APPENDIX V 227


230 ENGINEERING STANDARDS
APPENDIX V 231

p (PfTCH) »»

THREAD FORM - RECOMMENDED METRIC SERIES

p (PITCH) Ji^

THREAD FORM - ISO METRIC AND ISO INCH SERIES

FIGURE 6 - THREAD FORM COMPARISON,

ISO INCH, ISO METRIC AND RECOMMENDED

METRIC DIAMETER/PITCH SERIES.
232 ENGINEERING STANDARDS

ANNEX A - COMPUTER PROGRAMS

During the study, several computer programs were designed for

computing by direct or iterative approach. The majority yielded

data within two main sets of parameters -

a) Distribution of load transmitting capability (RF) - linear, parabolic, geometric progression, preferred

numbers, etc.

b) Relationships between stress concentration factors

(SCF) , ratio of areas (RA) , thread pitches, and root

radii proportions (RRPP)

Over 140 separate computer runs were made. The principal ones were -

1 - to determine RF for a diameter series with sizes

increasing by 'v^'S (18.9%), for sizes 1 thru 100 mm

and with P-A graduated from 65 thru 88%.

2 - same as 1 but with sizes increasing by (14%).

3 - Same as 1 but with sizes selected from a combination

of the RIO and R20 preferred number series.

4 - to determine a 26 size dia/pitch series, with RA

graduated from 65 to 88%, and with constant RF of

Y2 (1.4142).

5 - same as 4 but with constant RF of 1.3333.

6 - same as 4 but with a linear distribution of RF from

2.0000 to 1.2500.

7 - same as 4 but with a linear distribution of RF from

1.7500 to 1.2500.

8 - same as 4 but with a linear distribution of RF from

1.5000 to 1.2500.

9 - same as 7 but with 27 sizes in the series. ,

10 - same as 7 but with 25 sizes in the series.

11 - to determine a 25 size dia/pitch series, with RA

graduated from 65 to 88%, and with a geometric progression of RF from 1.7500 to 1.2500.

12 - same as 11 but with geometric progression of RF from

2.0000 to 1.2000.

3A - same as 3 but with RA graduated from 62 to 90%.

Annex A—
APPENDIX V 233

lOA - same as 10 but with RA graduated from 62 to 90%.

12A - same as 12 but with RA graduated from 62 to 90%.

100 - to determine RRPP and root radius of thread of

Series 3 with constant SCF of 3.0.

101 - to determine SCF of Series 3 with RRPP of .180.

102 - to determine thread pitch and RA of Series 3 with

RRPP of .180 and constant SCF of 2.85.

103 - same as 102 but with constant SCF of 3.15.

104 - same as 102 but with constant SCF of 3.25.

200 - to determine SCF of Series 10 with RRPP of .180.

301 - to determine RA, RF , SCF of ISO inch coarse thread

series, sizes No. 1 thru 4 in., with RRPP of .14434.

(Annex B-2i

302 - same as 301 but for ISO inch fine thread series,

sizes No. 000 thru 1-1/2 in. (Annex B-3)

303- 1 - same as 301 but for ISO metric coarse thread series,

sizes 1 thru 100 mm. (Annex B-1)

304- 1 - same as 301 but for ISO metric fine thread series,

sizes 8 thru 39 mm. (Annex B-3)

305 - to determine RA, RF, and SCF of "first selection"

of recommended metric dia/pitch series with RRPP

of .150.

306 - same as 305 but with RRPP of .180.

307 - to determine RF , SCF and thread pitches of "first

selection" of recommended metric dia/pitch series

with RA uniformly graduated from 57 to 71% thru

size range of 1 to 8 mm, and with RRPP of .150.

308 - same as 307 but with RRPP of .180.

401 - to determine RA, RF, SCF of "final" recommended

metric dia/pitch series with RRPP of .150.

402 - same as 401 but with RRPP of .180. (Annex B-4)

NOTE: - the computer print outs for 301, 302, 303-1, 304-1,

and 402 are given in Annex B.

Annex A—

2
234 ENGINEERING STANDARDS

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APPENDIX V 235

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Annex B-2

422-764 OL - 71 - 16
236 ENGINEERING STANDARDS

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Annex B—
APPENDIX V 237

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Annex B—

4
238 ENGINEERING STANDARDS

ISO / R 272 -ISM (E) ISO Recommendation R 272 February 1968

HEXAGON BOLTS AND NUTS

WIDTHS ACROSS FLATS, HEIGHTS OF HEADS,

THICKNESSES OF NUTS

METRIC SERIES

i

Dimensions in millimetres

Threid Width* HetgM Thicknes)

diunclcf across flats of head of nut d normtl small k m

1.6 3.2 1.1 1.3

2 4 1.4 1.6

2.5 5 1.7 2

3 5.5 2 2.4

4 7 2.8 3.2

5 8 3.5 4

6 10 4 5

7 1

5 5.5

8 13 12 5.5 6.5

10 17 14 7 8

12 19 17 8 10

14 22 19 9 11

16 24 22 10 13

18 27 24 12 15

20 30 27 13 16

22 32 30 14 18

24 36 32 15 19 27 41 36 17 22

iQ 46 41 19 24

33 50 46 21 26

}6 55 50 23 29 39 6Q 5S 25 31

Ttiread diameter dWidth

acroaa flats

s

Height

of head

k

ThiclcneM

of nut m

42 65 26 34 45 70 28 36 48 75 30 38 52 80 33 42

56 85 35 45 60 90 38 48

64 95 40 51 68 100 43 54 72 105 45 58

76 110 48 61 80 115 50 64

85 120 54 68

90 130 57 72 95 135 60 76 100. 145 63 80

105 150 66 84 110 155 69 88

115 165 72 92 120 170 76 %

125 180 79 100 130 185 82 104 140 200 88 112 ISO 210 95 120

Where larger metric hexagons are required, the next larger width acrou flats for any given diameter, as shown in the normal metric aeries, should be chosen, leaving the other dimensions unchanged.

Annex C—
APPENDIX V 239

ANNEX D - METHOD FOR DETERMINING STRESS CONCENTRATION FACTOR

For fatigue evaluation in axial mode of threaded fasteners, both

the static and alternating stress components must be determined.

The static stress component can be considered as being primarily

dependent on the stress area. The alternating stress component

will be dependent on the stress area and the effective stress

concentration factor.

Stress concentrations occur in thread roots due to two simultaneous

types of loadings:

1. Axial bolt loading (Core load)

2. Local thread projection loading (Thread load)

The actual magnitudes of core and thread loading are influenced by

many factors in the mating threads, and therefore, cannot be

determined with great accuracy.

Stress concentration factors (SCF) due to core loadina were determined by using the methods given by Neuber (1) and Heyv/ood (2) . According to Neuber, the stress concentration factor in a single

circumferential "U" notch in a round specimen is a function of a/p

and t/j) where a is the shank radius of the notch at the root, 9

is the radius of curvature of the root, and t is the depth of the

notch. Using the stress concentration factors for shallow notches

and deep notches, a stress concentration factor for a notch of

arbitrary depth can be given as

{o<r - 1). {^tk - 1)

y('^</i7-i)^ + 7^^Ar^~^7^

where

°<^^ = stress concentration factor for a notch of

arbitrary depth

<3^^^ = stress concentration factor for a shallow notch

<=^tk~ stress concentration factor for a deep notch

The obtained stress concentration factors then can be corrected for;

a) Load relieving effects of multiple notches by using a load relieving factor g which is given as a function

of (b/t) where b is the pitch between the notches.

(Ref. 1, p. 206 eq. (24) and Fig. 93)

Annex D—

1

422-764 OL - 71 - 17
240 ENGINEERING STANDARDS

b) Flank angle effects (Ref. 2, eq. 6-12)

where

JB = flank angle

<=< = corrected stress concentration value

These methods and modifications will be used in determining the stress

concentration factor for a threaded section due to axial load alone

based on the maximum axial stress criterion.

New symbols for parameters to be used in further calculations are:

DMI - minor diameter

P = pitch

T = depth of thread

RR = root radius

L) = Poisson's Ratio

With these symbols the constituent parts of equation (1) can be rewritter

as

(Ref. 1, p 132, eq. 59, 6]

where

N = (DR) + 2p I/TdrT + I +2 ,

i;

Annex D—

and

DR DMI/ 2RR
APPENDIX V 241

The calculated and cKtK factors then can be entered into equations

(1) and (2) for obtaining the stress concentration factor (SCF) for a threaded section with a 30 deg flank angle due to axial load alone and

will take the form of

j(l + 2.4/^T/RR)

J-^-j SCF = 1 + (o< ,^ - 1).(1 - .3333)'

The three major geometric ratios involved in calculations of SCF are

(DMI/2RR) , (T/RR) and (P/T) \6]

All of these parameters in the case of threaded fasteners can be

related to pitch. Consequently, v;ith the specified root radius to

pitch proportion (RRPP) and the depth of thread engagement, the rest

of the parameters in the ratios of eq. (6) will also be predetermined.

In any series of fasteners where it would be required to have a constant

stress concentration factor (SCF) , the above three ratios must be

constant or nearly constant. By maintaining a uniform RRPP for the

entire series, a series with a constant SCF can be derived at the

expense of disproportioned pitches.

Additional stress effects in engagement can be considered by introducing the overall stress concentration factor (SCFO) for dynamic rating

of the screw-nut system. This factor can be given as

SCFO = SCF I 1 + 1/ (1 + C " SR) SR

(Ref. 2)

where

C = ^(60 -@ )/44)^ = a thread constant

= inclination of flank to radial plane, degrees

C = .465 for 6 0 deg thread form (30 deg flank

angle

)

SR = S /S = stress ratio

a' p

S = maximum root stress due to axial load alone.

^ SCF is based on S a

S = maximum root stress due to the local projection

^ (cantilever loading on thread flank) load alone. _ This stress is a function of several parameters.

By maintaining the predetermined pitch and root

Annex D—

3
242 ENGINEERING STANDARDS

radius dimensions or proportions and thread

angles, the length of helix of thread in

engagement becomes the controlling parameter

in changing the and SR quantities. -

The stress concentration factor due to axial load alone (SCF) in

equation (7) can be treated as the predominant indicator of the

dynamic performance of a threaded fastener. The notch sensitivity

of involved materials and the stress ratio (SR) are the remaining

factors needed to determine the dynamic rating of a fastener.

By maintaining a constant stress ratio (SR) the overall stress con- centration factor (SCFO) will remain constant. With the specified

pitch and root radius dimensions and thread flank angles ^ the helix

length of thread in contact with the nut (height of the nut) becomes

theoretically the controlling parameter in changing the Sp and SR

quantities. At the present phase of the task, the SCFO factors were

not computed. In addition, considerations of notch sensitivities of

involved materials would be required for a true dynamic rating of a fastener

If the true dynamic rating of a fastener is not required or cannot be

practically achieved, then the stress concentration factor (SCF) in

conjunction with the static rating would become one of the better

indicators of dynamical performance.

REFERENCES

1. H. Neuber, "Theory of Notch Stresses: Principles for Exact Calculations of Strength with References to Structural Form and

Material", Translated from a publication of Springer-Verlag

,

Berlin, Goettingen, Heidelberg 1958, (AEC-tr-4547 )

2. R. B. Heywood , "Designing by Photoelasticity" , Chapman & Hall

Ltd. , London 1952.

Annex D—
APPENDIX V 243

TABLE 1 - STRESS CONCENTRATION FACTOR (SCF) TO THREAD

PITCH RELATIONSHIP FOR DIAMETERS 5 THRU 30 nm

WITH RRPP = .150

\^CF 2. 75 2.80 2.85 2. 90 2.95 3. 00

i HKijAU f ± LK^n BASIC

DIA mmTHREAD PITCH, mm (COMPUTED)

RECOMMENDED

METRIC SERIES

5 1. 043 . 983 . 917 • 855 .797 • 735 .9 6.3 1. 317 1.241 1.159 1. 081 1.000 922 1

8 1. 677 1.566 1.476 1. 363 1.273 1. 176 1.25

10 2. 095 1.956 1. 844 1. 722 1.591 1. 456 1.5

12.5 2. 616 2.443 2.303 2. 150 1.986 1. 835 1.75

16 3. 332 3.140 2.960 2. 734 2.553 2. 337 2 20 4. 193 3.916 3.691 3. 409 3.184 2. 914 2.5

25 5. 209 4.910 4.628 4. 275 3.992 3. 653 3 30 6. 253 5.894 5.504 5. 140 4.748 4. 434 3.5

NOTE: - RRPP = root radius in proportion to thread pitch.

TABLE 2 - STRESS CONCENTRATION FACTOR (SCF) TO THREAD

PITCH RELATIONSHIP FOR DIAMETERS 5 THRU 30 mm

WITH RRPP = .180

\.,^^CF 2. 75 2.80 2.85 2. 90 2.95 3. 00

THREAD PITCH

BASIC

DIA

mm THREAD PITCH, mm (COMPUTED)

RECOMMENDED

METRIC SERIES

5 847 .781 .721 651 .589 522 .9 6.3 1. 071 .989 .904 817 .739 668 1

8 1. 363 1.248 1.152 1. 042 .942 834 1.25

10 1. 703 1.576 1,442 1. 318 1.191 1. 055 1.5

12.5 2. 127 1.968 1.801 1. 648 1.476 1. 307 1.75

16 2. 709 2.502 2.290 2. 076 1.900 1. 683 2 20 3. 409 3.120 2.855 2. 613 2.369 2. 121 2.5

25 4. 325 3.912 3.580 3. 246 2.971 2. 635 3 30 5. 140 4.704 4.305 3. 930 3.533 3. 164 3.5

NOTE: RRPP root radius in proportion to thread pitch.

Annex D—

5
244 ENGINEERING STANDARDS

4. DIAMETER/PITCH COMBINATIONS

TABLE - Diunettr/pllch Dimensions in millimetres

Nomlnil diameters Pltchei

Col 1 tst choiceCol. 2 2nd

choice

Col. 3 3rd

choice

coarse

fine

3 2 1.5 1.25 1 0.75 0.5 0.35 0.25 0.2

1 0.25 0.2

1.2

1.1

1.4

0.25

0.25

0.3

0.2

0.2

0.2

1 .6

2

1.8

0.35

0.35

0.4 0.25

0.2 0.2

2.5 3

2.2 0.45

0.45

0.5

0.35

0.35

0.25

4

3.5

4.5

0.6

0.7 0.75

0.5

0.5

0.35

5

6

5.5

0.8

1 0.75

0.5

0.5

8

7

9

11.25

1.25

0.75 0 75

0.75 10

12

11

1.5 1.5' 1.75 1.51.25

1.25

0.75

0.75

16

14

15

2

2

1.5

1.5 1.5

1.25'

;

20

18

17

2.5

2.5

2

2

1.5

1.5

1.5

24

22

25

2.5

3

2

22

1.5

1.5 1.5

27

26

28

3 2

2

1.5 1.5

1.5 30

33

32

3.5

3.5

(3)

(3)

22

2

1.5

1.5

1.5

36

39

35**

38

4

4

3

3

2

2

1.5 1.5

1.5

1.5

* Only for spark plugs for engines.

** Only for locking nuts for beirlngs.

Avoid as far a$ possible pitches in bi^ckets.

Annex E—
APPENDIX V 245

TABLE - tHtinmi/pltch iconeludtd) Dlmenilon» In mlUlmsUci

Nomliul diameten Fitchei

Col. 1 Col. 2 Col. 3 One

1st 2nd 3rd coaise

choice choice choice 6 4 3 2 1.5

40 3 2 1.5 42 4.5 4 3 2 1.5 45 4.5 4 2 1.5 48 5 4 3 2 1.5 50 3 2 1.5 52 5 4 3 2 1.5 55 4 3 2 1.5 S6 5.5 4 3 2 1.5 58 4 3 2 1.5 60 5.5 4 3 2 1.5 62 4 3 2 1.5 64 6 4 3 2 1.5 65 4 3 2 1.5 68 6 4 3 2 1.5 70 6 4 3 2 1.5 72 6 4 3 2 1.5 75 4 3 2 1.5 76 6 4 3 2 1.5 78 2 80 6 4 3 2 1.5 82 2 85 6 4 3 2 90 6 4 3 2 95 6 4 3 2 100 6 4 3 2 105 6 4 3 2 110 6 4 3 2 115 6 4 3 2 120 6 4 3 2 125 6 4 3 2 130 6 4 3 2 135 6 4 3 2 140 6 4 3 2 145 6 4 3 2 150 6 4 3 2 155 6 4 3 160 6 4 3 165 6 4 3 170 6 4 3 175 6 4 3 180 6 4 3 185 6 4 3 190 6 3 195 6 4 3 200 6 4 3 205 6 4 3 210 6 4 3 215 6 4 3 220 6 4 3 225 6 4 3 230 6 4

1 235 6 4 240 6 4 245 6 4 250 6 4

255 6 4 260 6 4 265 6 4 270 6 4 275 6 4 280 6 4 285 6 4 290 6 4 295 6 4 300 6 4

Annex E—

2
246 ENGINEERING STANDARDS

4. SCREW THREADS

Table 1.

Nnmbcr of threads per Inch

Sizes Basic Ma|or

diameter

in

Series with graded pitches Scries with constant (uniform) pitches

Pri- mary

Secon- dary

thread

series UNC

thread

scries UNF

Extrafine thread

series UNEF

4-thrcad

series

UN

6-thrcad

series

UN

8-thread

series

UN

12- thread

series UN

16- thread

series UN

20- thread

series UN

28- thread

series UN

32- Ihrcad

scries UN

1 2 3 4 5 6 7 8 9 10 II 12 13 14

No.O

No. 1

0.060 0

0.073 0 64

80

72 No. 2 0.086 0 56 64

No. 3 0.099 0 48 56 No. 4 0.1120 40 48 No. 5 0.125 0 - 40 44

No. 6 0.138 0 32 40 UNC

No. 8 0.164 0 32 36 UNC

No. 10 No. 1

0.190 0

0.216 0

24

24

32

28 32 UNF

UNF

UNEF

V4 0.250 0 20 28 32 UNC UNF UNEF

Vie 0.312 5 18 24 32 20 28 UNEF

0.375 0 16 24 32 UNC 20 28 UNEF

Vie 0.437 5 14 20 28 16 UNF UNEF 32 0.500 0 13 20 28 16 UNF UNEF 32

Vie 0.562 5 12 18 24 UNC 16 20 28 32

Vs 0.625 0 11 18 24 12 16 20 28 32

•Vie 0.687 5 24 12 16 20 28 32 V4 0.750 0 10 16 20 12 UNF UNEF 28 32

"/le 0.812 5 20 12 16 UNEF 28 32 Vs 0.875 0 9 14 20 12 16 UNEF 28 32

'Vie 0.937 5 20 12 16 UNEF 28 32

1 IVie

1.000 0

1.062 5

8 12 20

18 UNC

8 UNF12

16

16 UNEF20

28

28

32

1 Vs 1.1250 7 12 18 8 UNF 16 20 28

IVie 1.187 5 18 8 12 16 20 28 1V4

1 5/,, /16

1.250 0

1.312 5

7 12 18

1 s1 0

8

Q0 UNF

1 1i.

16

1 f\ 1

20 28

IVb

IVie

1.375 0

1.437 5

6 12 18

18 UNC6

8

8 UNF12

16

16

20

20

28

28 IV2 1.500 0 6 12 18 UNC 8 UNF 16 20 28

IVie 1.562 5 18 6 8 12 16 20 IVe

1 "/le

1.625 0

1.687 5

18

18

6

6

8

8

12

12

16

16

2020

IV4

1 "Ae

1.750 0

1.812 5

5 6

6

8

8

12

12

16

16

20

20 IVs 1.875 0 6 8 12 16 20

* Selected series for screws, bolts and nuts, and first choice Tor general engineering applications. (continued)

Annex E—
APPENDIX V 247

Table I. - (concluded)

Nvnbcr of thread! per Inch

Site* Dalle major

diameter

Serlea with graded pilches Series with constant (uniform) pitches

Pri- miry

Secon- dary in

Coarse

thread

series UNC

Fine

thread

series UNF

Extraflne thread

series UNEF

4-thread

series

UN

6-thread

series

UN

8-thread

series

UN

12- thread

series UN

16- thread

series UN

20- thread

series UN

28- thread

series UN

32- thread

series UN

1 2 3 4 5 ( 7 g 9 10 ] 1 12 13 14

1 1.937 5 6 8 12 16 20

2 2V8

2.000 0

2.125 0 4Va 66

88

12

12

16

16

20

20

2V4

2V8

2.250 0

2.375 0 4Va 66

8

8

12

12

1616

20

20 2V« 2.500 0 4 UNC 6 g 12 16 20

20/8 2.625 0 4 6 8 12 16 20

2*Ia

2'/«

2.750 0

2.875 0

4 UNC

4

6

6

88

12

12

1616

20

20

3 3V8

3.000 0

3.125 0

4 UNC

4

6

6

8

8

12

12

16

16

20

' /4 3.250 0 4 UNC 8 12 16

3'/8 3.375 0 4 6 8 12 16

3»/«

/8

3.500 0

3.625 0

4 UNC

4

6

6

8

8

12

12

16

16

3'/8

3.750 0

3.875 0

4 UNC

4

6

6

881212

16

16 4 4.000 0 4 UNC 6 8 12 16

4V8 4.125 0

- -- 4 6 8 12 16

41/4 4.250 0

4.375 0

44

6

5

8

g

121216

16

4»/8

4 son fi 4.625 0

4

4

668

8

12

12

16

16 4V4 4.750 0 4 6 8 12 16

4'/8 4.875 0 4 6 8 12 16

5 5.000 0

5.125 0

44

66

88

12

12

16

16

51/4

53/8

5.250 0

5.375 0

4

4

6

6

8

8

1212

16

16 5.500 0 4 6 8 12 16

5.625 0 4 6 8 12 16 5V4

5'/8

5.750 0

5.875 0

4

4

6688

121216

16 6 6.000 0 4 6 8 12 16

* Selected series Tor screws, bolts and nuts, and first choice Tor general engineering applications.

Annex E—

4
248 ENGINEERING STANDARDS

ANNEX F - MEMBERSHIP OF IFI TECHNICAL COMi^lITTEES

STANDARDS AND TECHNICAL PRACTICES COMMITTEE

A. R. Breed, Chm.

D. E. Batty

T. C. Baumgartner

A. G. Baustert

H. R. Chappell, Jr,

R. T. Christenson

C. J. Czerski

W. R. Davis

G. Dreger

R. W. Groover

R. W. Harrison

R. C. Kozlik

c. B. Lanman

R. B. Leeds

J. C. McMurray

J. F, Morrow

H. G. Muenchinger

R. C. Nichols

J. S. Orlando

M. Popyk

J. R. Preziosi

L, A, Proulx

L. E. Saraz

J. Shugart

V. CSt impel

T. E. Uriah

E. C. Wilson

H. Wittmeyer

R. B. Belford, Se

The Lamson & Sessions Co.

Standard Nut & Bolt Co.

Standard Pressed Steel Company

Federal Screw Works

Ring Screw Works

Wrought Washer Mfg. Co.

Lake Erie Screw Corporation

Armco Steel Corporation

P. L. Robertson Manufacturing Company Ltd.

Bethlehem Steel Corporation

Towne Robinson Fastener Co.

- Subsidiary of Key International, Inc.

National Lock Fasteners

- Div. of Keystone Consolidated Industries

Lanman Bolt & Forge Co., Inc.

John Hassall, Inc.

Russell, Burdsall & Ward Bolt and Nut Co.

The National Screw and Manufacturing Compan

Continental Screw Company

Jos. Dyson & Sons Inc.

H. M. Harper Company

Zimmer Manufacturing Ind. Inc.

Elastic Stop Nut Division

- Amerace Esna Corporation

Phillips Screw Company

Republic Steel Corporation

- Bolt and Nut Division > Rockford Products Corporation

MacLean-Fogg Lock Nut Company

Gripco Fastener Division

- MITE Corporation

Shakeproof Division

- Illinois Tool Works Inc.

Huck Manufacturing Company

Industrial Fasteners Institute

Annex F—
APPENDIX V 249

ENGINEERING COMMITTEE - DIVISION II - SMALL SCREW PRODUCTS

R. C . Kozlik, Chm. National Lock Fasteners

- Div. of Keystone Consolidated Industries

A. R. Breed The Lamson & Sessions Co.

G. Dreger P. L. Robertson Manufacturing Company Ltd.

R. C. Gates Butcher & Hart Manufacturing Co.

H. P. Key Rockford Products Corporation

J. C. McMurray Russell, Burdsall & Ward Bolt and Nut Co.

H. G. Muenchinger Continental Screw Company

L. A. Proulx Phillips Screw Company

B. F. Re i land Camcar Screw & Mfg.

K. P . Shuttleworth Armco Steel Corporation

J. J. Simko The National Screw and Manufacturing Company

E. C. Wilson Shakeproof Division

- Illinois Tool Works Inc.

R. B. Belford, Secy. Industrial Fasteners Institute

TASK DESIGN AND SIMPLIFICATION

A. R. Breed, Chm. The Lamson & Sessions Co.

T. C. Baumgartner Standard Pressed Steel Company

D. W. Griiran Elastic Stop Nut Division

- Amerace Esna Corporation

R. c. Kozlik National Lock Fasteners

- Div. of Keystone Consolidated Industries

J. c. McMurray Russell, Burdsall & Ward Bolt and Nut Co.

H. G. Muenchinger Continental Screw Company

J. S. Orlando H. M. Harper Company

J. Shugart Rockford Products Corporation

F, E . Smode Huck Manufacturing Company

R. B. Belford, Secy. Industrial Fasteners Institute

ACKNOWLEDGMENT

IFI acknowledges the contribution of Dr. Romualdas Kasuba,

Associate Professor of Mechanical Engineering, Cleveland

State University. Dr. Kasuba served as technical consultant to the Institute throughout the study, and was responsible for all computerized data generated during its conduct.

Dr. Kasuba is now preparing a detailed treatise for publication at a later date.

Annex F-2
250 ENGINEERING STANDARDS

ANNEX G - REFERENCES

1. Breed, A. R. and Kasuba, Romualdas, "New Concepts on Size

Modules for Fasteners and Related Hardware", American

Society for Mechanical Engineers, Paper 70-DE-22, presented

at Design Engineering Conference, May 1970.

2. "Screw Threads for Bolts and Nuts, - Swedish Proposal for

an International Standard", Sveriges Standardiseringskommission, February 1948.

3. Tornebaum, Dr. Hilding, "International Standardization of

Screw Threads" , The Bulletin of The American Society of

Swedish Engineers, Vol. XLVI , 1951-1952.

4. Ernst, H. , "Screw Threads", translation of paper by Ernst,

consulting engineer Le Chesnay (Sein-et-Oise) , Paris

ISO/TCI, WG4 Secretariat's document 55, 1963.

5. ISO Recommendation R68 "ISO General Purpose Screw Threads - Basic Profile", Second Edition, September 1969.

6. ISO Recommendation R261 "ISO General Purpose Metric Screw

Threads - General Plan", Second Edition, September 1969.

7. ISO Recommendation R263 "ISO Inch Screw Threads - General

Plan and Selection for Screws, Bolts, and Nuts, First

Edition, July 1962.

Annex G— 1
FORM NBS-114A 11.71) U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBS-SP-3^5-112. Gov't Accession

No.

3. Recipient's Accession No.

4. TITLE .^ND SUBTITLE U.S. Metric Study Interim Report:

Engineering Standards

5. Publication Date July 1971

6. Performing Organization Code

7. AUTHOR{S) Dr. Rotert D. Stiehler

8. Performing Organization

9. PERFORMING ORGANIZATION NAME AND ADDRESS NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No. !+063129

11. Contract/Grant No.

12. Sponsoring Organization Name and Address 13. Type of Report & Period Covered Interim

14. %>onsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary of mosr significant information. If document includes a significant bibliography or literature survey, mention it here.) This report, one of a series prepared pursuant to the U.S. Metric Study Act, is concerned with (l) the relationship "between measurement language and engineering

standards, and (2) the compatihility of U.S. Standards with corresponding international

standards. Incompatihilities between corresponding standards result from differences

of engineering practice. Measurement units contribute to the incompatibilities among

many dimensional specifications which comprise about 25$ of engineering standards. In the remaining standards , measurement units are either not involved or serve merely as a language. The study compares U.S. standards with other national and international

standards

.

7. KEY WORDS (Alphabetical order, separated by semicolons) engineering standards; international standard;

International System of Units; metric conversion; metric system; metrication; metrication and engineering standards; SI; standards; U.S. Metric Study

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