25940 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

DEPARTMENT OF TRANSPORTATION

Research and Special Programs

Administration

49 CFR Parts 171, 173, and 178

[Docket HM–220B; Admt. Nos. 171–142,

173–250, and 178–114]

RIN 2137–AC81

Restructuring of Cylinder

Specifications Requirements

AGENCY: Research and Special Programs

Administration (RSPA), DOT.

ACTION: Final rule.

SUMMARY: RSPA is amending the

Hazardous Materials Regulations (HMR)

by restructuring the cylinder

specification requirements in its

regulations on Specifications for

packagings. The intended effect of this

rulemaking is to reduce the size of the

HMR through consolidation of repetitive

requirements and other formatting

changes. This action eliminates

approximately 45 pages of regulations

from the Code of Federal Regulations

without substantially changing the

regulatory requirements or affecting

safety. It is in response to President

Clinton’s March 4, 1995 Regulatory

Reinvention Initiative memorandum to

heads of departments and agencies

calling for a review of all agency

regulations. RSPA is also making

corresponding reference changes

throughout the HMR.

DATES: Effective date: October 1, 1996.

Incorporation by reference date: The

incorporation by reference of certain

publications listed in these amendments

has been approved by the Director of the

Federal Register as of October 1, 1996.

FOR FURTHER INFORMATION CONTACT: John

A. Gale, (202) 366–8553; Office of

Hazardous Materials Standards, RSPA,

Department of Transportation,

Washington, DC 20590–0001.

SUPPLEMENTARY INFORMATION:

I. Background

On March 4, 1995, President Clinton

issued a Regulatory Reinvention

Initiative memorandum to heads of

departments and agencies calling for a

review of all agency regulations and

elimination or revision of those

regulations that are outdated or in need

of reform. RSPA has performed an

extensive review of the Hazardous

Materials Regulations (HMR; 49 CFR

Parts 171–180) and associated

procedural rules (49 CFR Parts 106 and

107) in response to the President’s

directive.

The President also directed that front

line regulators ‘‘* * * get out of

Washington and create grassroots

partnerships’’ with people affected by

agency regulations. On April 4, 1995,

RSPA published in the Federal Register

(60 FR 17049) a Notice of Public

Meetings and request for comment on

its hazardous materials safety program.

Comments were requested on ways to

improve the HMR and the kind and

quality of services its customers want.

RSPA held seven public meetings and

received over 50 comments in response

to the notice. On July 28, 1995, RSPA

published a second Notice of Public

Meetings in the Federal Register (60 FR

38888) which announced five more

public meetings that were held from

September 1995 through January 1996.

One area identified by RSPA in its

review of the HMR was the need to

reform the cylinder specifications in 49

CFR Part 178. On March 4, 1996 (61 FR

8328), RSPA proposed to amend the

HMR by restructuring the cylinder

specifications in Part 178. RSPA

estimates that by consolidating

duplicative requirements in 23 cylinder

specifications, that it will eliminate at

least 45 pages from the CFR. By

reformatting the specifications, RSPA

proposes to eliminate over 450 sections

from Part 178 of Title 49. The combined

effect of these changes will be to make

the regulations shorter and easier to use

and help RSPA move toward its goal of

issuing the HMR in one volume of the

Code of Federal Regulations, rather than

two.

This rulemaking also serves as the

model for a comprehensive rulemaking,

being developed by RSPA in

cooperation with the Compressed Gas

Association, for which a notice of

proposed rulemaking is anticipated later

this year. In this latter rulemaking,

under Docket HM–220, RSPA intends to

propose substantive changes to the

cylinder specifications to accommodate

contemporary manufacturing

techniques, eliminate obsolete

requirements, contemporize regulatory

language and make safety enhancements

to the regulations.

II. Summary of Amendments

RSPA received approximately 10

comments to the NPRM. All of the

comments were in support of the

proposal. One commenter stated that the

changes proposed under Docket HM–

220B are a valuable contribution to

simplification of the cylinder

specifications. Another commenter

stated that it strongly supports the

amendments proposed in Docket HM–

220B to simplify and update existing

regulations and to reduce the size of the

HMR by consolidation of the text.

Several commenters also raised

concerns that were beyond the scope of

the proposed rule; however, they may

be considered in future rulemakings.

In this final rule, RSPA is revising the

HMR by restructuring the cylinder

specification requirements in 49 CFR

Part 178. This restructuring of the

cylinder specifications: (1) consolidates

similar sections; (2) reformats subpart C

of Part 178 for consistency with the

format of the rest of Part 178; and (3)

revises section references throughout

the HMR to correspond to the revised

sections. RSPA intends to streamline the

cylinder specification requirements

without making substantive changes to

them.

Sections that have been consolidated

are the sections of each specification

addressing compliance, authorized

inspectors, duties of the inspector, the

inspector’s report, record retention,

defects, safety relief devices, and

marking. These sections have been

consolidated into a new § 178.35.

Section 178.35, entitled ‘‘General

requirements for specification

cylinders’’ prescribes the general

requirements for all DOT specification

cylinders. However, because some of the

duties of the inspector and marking

requirements are specific to individual

cylinder designs, some specifications

have additional marking and inspector

requirements remaining in their

sections.

For the inspector’s report, RSPA has

adopted the inspector report formats in

Compressed Gas Association (CGA)

Pamphlet C–11, ‘‘Recommended

Practices for Inspection of Compressed

Gas Cylinders at Time of Manufacture.’’

The report formats can be modified to

represent the inspection of specific

cylinders. Additional information may

be required as stated in each

specification. In order to help facilitate

transition into the new reports, RSPA is

allowing inspectors an additional year,

until October 1, 1997, to use the old

report format required by the HMR.

Those sections remaining in each

specification have been consolidated

into a single section. Presently, each

specification is set forth in

approximately 22 different sections.

Under this final rule, there is only one

section for each specification. For

example, Specification 3B was set forth

in 24 sections, §§ 178.38 through

178.38–23. In this final rule,

Specification 3B is set forth in one

section, § 178.38, and some of its

requirements are relocated in § 178.35.

Sixteen of the old sections are converted

to paragraphs (a) through (o) of § 178.38.

As an aid to the reader, the regulatory
Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations 25941

text in this final rule includes all of the

requirements for cylinders in the

current Subpart C of part 178, even

though not all of the requirements are

changed.

In response to comments, RSPA has

made several changes to the original

proposal. RSPA has corrected the

minimum service pressure for the DOT

Specification 4E cylinder to 225 psig. In

the NPRM, RSPA incorrectly proposed

the minimum service pressure for the 4E

cylinder at 250 psig.

In the NPRM, RSPA proposed to

revise the marking requirements for the

DOT Specification 39 to indicate that

the highest monetary penalty under the

Federal hazardous materials

transportation law was $500,000 and

not $25,000. One commenter, citing the

costs of updating silk-screens, requested

that RSPA not adopt this change. RSPA

has not adopted this commenter’s

suggestion because the marking should

accurately reflect the requirements of

the Federal hazardous materials

transportation law. However, RSPA is

adding a ‘‘grandfather’’ provision for

those containers marked prior to

October 1, 1996.

In § 178.35(b)(2), RSPA is adding a

reference to the DOT Specification 3E.

RSPA had inadvertently left reference of

that specification out of that section.

The purpose of this rulemaking action

is to reduce the size of the HMR and

make it easier to use. It is not intended

to make substantive changes to

regulatory requirements and no adverse

impacts are anticipated on the regulated

community.

III. Regulatory Analyses and Notices

Executive Order 12866 and DOT

Regulatory Policies and Procedures

This final rule is not considered a

significant regulatory action under

section 3(f) of Executive Order 12866

and was not reviewed by the Office of

Management and Budget. The rule is not

considered significant under the

regulatory policies and procedures of

the Department of Transportation (44 FR

11034). The economic impact of this

rule is minimal to the extent that the

preparation of a regulatory evaluation is

not warranted.

Executive Order 12612

This final rule has been analyzed in

accordance with the principles and

criteria contained in Executive Order

12612 (‘‘Federalism’’). The Federal

hazardous materials transportation law

(49 U.S.C. 5101–5127) contains an

express preemption provision that

preempts State, local, and Indian tribe

requirements on certain covered

subjects. Covered subjects are:

(i) the designation, description, and

classification of hazardous material;

(ii) the packing, repacking, handling,

labeling, marking, and placarding of

hazardous material;

(iii) the preparation, execution, and

use of shipping documents pertaining to

hazardous material and requirements

respecting the number, content, and

placement of such documents;

(iv) the written notification,

recording, and reporting of the

unintentional release in transportation

of hazardous material; or

(v) the design, manufacturing,

fabrication, marking, maintenance,

reconditioning, repairing, or testing of a

package or container which is

represented, marked, certified, or sold

as qualified for use in the transportation

of hazardous material.

The Federal hazardous materials

transportation law provides that if DOT

issues a regulation concerning any of

the covered subjects after November 16,

1990, DOT must determine and publish

in the Federal Register the effective date

of Federal preemption. 49 U.S.C.

5125(b)(2). That effective date may not

be earlier than the 90th day following

the date of issuance of the final rule and

not later than two years after the date of

issuance. RSPA has determined the

effective date of Federal preemption for

these requirements is October 1, 1996.

This final rule deals with the packaging

of compressed gases. Because RSPA

lacks discretion in this area, preparation

of a federalism assessment is not

warranted.

Regulatory Flexibility Act

I certify that this final rule will not

have a significant economic impact on

a substantial number of small entities.

This final rule does not impose any new

requirements on persons subject to the

HMR.

Paperwork Reduction Act

This final rule does not propose any

new information collection

requirements.

Regulation Identifier Number (RIN)

A regulation identifier number (RIN)

is assigned to each regulatory action

listed in the Unified Agenda of Federal

Regulations. The Regulatory Information

Service Center publishes the Unified

Agenda in April and October of each

year. The RIN number contained in the

heading of this document can be used

to cross-reference this action with the

Unified Agenda.

List of Subjects

49 CFR Part 171

Exports, Hazardous materials

transportation, Hazardous waste,

Imports, Incorporation by reference,

Reporting and recordkeeping

requirements.

49 CFR Part 173

Hazardous materials transportation,

Packaging and containers, Radioactive

materials, Reporting and recordkeeping

requirements, Uranium.

49 CFR Part 178

Hazardous materials transportation,

Incorporation by reference, Motor

carrier safety, Packaging and containers,

Reporting and recordkeeping

requirements.

In consideration of the foregoing, 49

CFR parts 171, 173, and 178 are

amended as follows:

PART 171—GENERAL INFORMATION,

REGULATIONS, AND DEFINITIONS

1. The authority citation for Part 171

continues to read as follows:

Authority: 49 U.S.C. 5101–5127; 49 CFR

1.53.

2. In § 171.7(a)(3), in the table, under

the entry ‘‘Aluminum Standards and

Data, Seventh Edition, June 1982’’, the

section reference ‘‘178.65–5’’ is revised

to read ‘‘178.46 and 178.65’’, under the

entry National Institute of Standards

and Technology the entry for ‘‘USDC,

NBS Handbook H–28’’ is amended by

adding a section reference to read ‘‘;

178.46’’, under the entry American

Society for Testing and Materials the

entries for ASTM A 240–82, and ASTM

B 557–84 are revised and two new

entries are added in appropriate alphanumerical order, and under the entry

Compressed Gas Association, Inc., the

entries for CGA Pamphlet C–3 and CGA

Pamphlet C–12 are revised and a new

entry is added in alpha-numerical order

to read as follows:

§ 171.7 Reference material.

(a) * * *

(3) * * *
25942 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

Source and name of material 49 CFR reference

* * * * * * *

American Society for Testing and Materials

* * * * * * *

ASTM A 240–82 Standard Specification for Heat-Resisting Chromium and Chromium-Nickel

Stainless Steel Plate, Sheet and Strip for Fusion-Welded Unfired Pressure Vessels, Revision

A.

178.57; 178.358; 179.100; 179.200; 179.201;

179.220; 179.400.

* * * * * * *

ASTM B 557–84 Tension Testing Wrought and Cast Aluminum and Magnesium-Alloy Products 178.46; 178.251.

* * * * * * *

ASTM E 112–88 Standard Test Methods for Determining Average Grain Size ............................ 178.44.

ASTM E 290–92 Standard Test Method for Semi-Guided Bend Test for Ductility of Metallic Materials.178.46.

* * * * * * *

Compressed Gas Association, Inc.,

* * * * * * *

CGA Pamphlet C–3, Standards for Welding and Brazing on Thinned Walled Containers, 1975 178.47; 178.50; 178.51; 178.53; 178.54;

178.56; 178.57; 178.58; 178.59; 178.60;

178.61; 178.65; 178.68.

* * * * * * *

CGA Pamphlet C–11, Recommended Practices for Inspection of Compressed Gas Cylinders at

Time of Manufacture, 1993.

178.35.

CGA Pamphlet C–12, Qualification Procedure for Acetylene Cylinder Design, 1994 .................... 173.34; 173.303; 178.59; 178.60.

* * * * * * *

* * * * *

PART 173—SHIPPERS—GENERAL

REQUIREMENTS FOR SHIPMENTS

AND PACKAGINGS

3. The authority citation for Part 173

continues to read as follows:

Authority: 49 U.S.C. 5101–5127; 49 CFR

1.53.

§ 173.34 [Amended]

4. In § 173.34, paragraph (h) is

amended by:

a. Removing, in the first sentence, the

phrase ‘‘§§ 178.36–9(a), 178.37–9(a),

178.38–9(a), and 178.40–9(a)’’ and

replacing it with the phrase

‘‘§ 178.36(e), 178.37(e), 178.38(e), and

178.40(e)’’.

b. Removing, in the fourth sentence,

the phrase ‘‘§ 178.36–9(a), § 178.37–9(a),

§ 178.38–9(a), or § 178.40–9(a)’’ and

replacing it with the phrase

‘‘§ 178.36(e), 178.37(e), 178.38(e), or

178.40(e)’’.

§ 173.316 [Amended]

5. In § 173.316, in paragraph (a)(8),

the section reference ‘‘178.57–20(a)(4)’’

is revised to read ‘‘178.35’’ and in

paragraph (c)(3)(ii) the section reference

‘‘178.57–20’’ is revised to read ‘‘178.35’’.

PART 178—SPECIFICATIONS FOR

PACKAGINGS

6. The authority citation for Part 178

continues to read as follows:

Authority: 49 U.S.C. 5101–5127; 49 CFR

1.53.

7. Subpart C of Part 178 is revised to

read as follows:

Subpart C—Specifications for

Cylinders

Sec.

178.35 General requirements for

specification cylinders.

178.36 Specification 3A and 3AX seamless

steel cylinders.

178.37 Specification 3AA and 3AAX

seamless steel cylinders.

178.38 Specification 3B seamless steel

cylinders.

178.39 Specification 3BN seamless nickel

cylinders.

178.42 Specification 3E seamless steel

cylinders.

178.44 Specification 3HT seamless steel

cylinders for aircraft use.

178.45 Specification 3T seamless steel

cylinders.

178.46 Specification 3AL seamless

aluminum cylinders.

178.47 Specification 4DS welded stainless

steel cylinders for aircraft use.

178.50 Specification 4B welded or brazed

steel cylinders.

178.51 Specification 4BA welded or brazed

steel cylinders.

178.53 Specification 4D welded steel

cylinders for aircraft use.

178.55 Specification 4B240ET welded or

brazed cylinders.

178.56 Specification 4AA480 welded steel

cylinders.

178.57 Specification 4L welded insulated

cylinders.

178.58 Specification 4DA welded steel

cylinders for aircraft use.

178.59 Specification 8 steel cylinders with

porous fillings for acetylene.

178.60 Specification 8AL steel cylinders

with porous fillings for acetylene.

178.61 Specification 4BW welded steel

cylinders with electric-arc welded

longitudinal seam.

178.65 Specification 39 non-reusable (nonrefillable) cylinders.

178.68 Specification 4E welded aluminum

cylinders.

Subpart C—Specifications for

Cylinders

§ 178.35 General requirements for

specification cylinders.

(a) Compliance. Compliance with the

requirements of this subpart is required

in all details.

(b) Inspections and analyses.

Chemical analyses and tests as specified

must be made within the United States

unless otherwise approved in writing by

the Associate Administrator, in

accordance with § 173.300b of this

subchapter. Inspections and

verifications must be performed by—
Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations 25943

(1) An independent inspection agency

approved in writing by the Associate

Administrator, in accordance with

§ 173.300a of this subchapter; or

(2) For DOT Specifications 3B, 3BN,

3E, 4B, 4BA, 4D (water capacity less

than 1,100 cubic inches), 4B240ET,

4AA480, 4L, 8, 8AL, 4BW, 39 (marked

service pressure 900 p.s.i.g. or lower)

and 4E manufactured in the United

States, a competent inspector of the

manufacturer.

(c) Duties of inspector. The inspector

shall determine that each cylinder made

is in conformance with the applicable

specification. Except as otherwise

specified in the applicable specification,

the inspector shall perform the

following:

(1) Inspect all material and reject any

not meeting applicable requirements.

For cylinders made by the billetpiercing process, billets must be

inspected and shown to be free from

pipe, cracks, excessive segregation and

other injurious defects after parting or,

when applicable, after nick and cold

break.

(2) Verify the material of construction

meets the requirements of the applicable

specification by—

(i) Making a chemical analysis of each

heat of material;

(ii) Obtaining a certified chemical

analysis from the material manufacturer

for each heat of material (a ladle

analysis is acceptable); or

(iii) If an analysis is not provided for

each heat of material by the material

manufacturer, by making a check

analysis of a sample from each coil,

sheet, or tube.

(3) Verify compliance of cylinders

with the applicable specification by—

(i) Verifying identification of material

is proper;

(ii) Inspecting the inside of the

cylinder before closing in ends;

(iii) Verifying that the heat treatment

is proper;

(iv) Obtaining samples for all tests

and check chemical analyses;

(v) Witnessing all tests;

(vi) Verify threads by gauge;

(vii) Reporting volumetric capacity

and tare weight (see report form) and

minimum thickness of wall noted; and

(viii) Verifying that each cylinder is

marked in accordance with the

applicable specification.

(4) Furnish complete test reports

required by this subpart to the maker of

the cylinder and, upon request, to the

purchaser. The test report must be

retained by the inspector for fifteen

years from the original test date of the

cylinder.

(d) Defects. A cylinder may not be

constructed of material with seams,

cracks, laminations, or other injurious

defects.

(e) Safety devices. Safety devices and

protection for valves, safety devices, and

other connections, if applied, must be as

required or authorized by the

appropriate specification, and as

required in §§ 173.34 and 173.301 of

this subchapter.

(f) Markings. Markings on a DOT

Specification cylinder must conform to

applicable requirements.

(1) Each cylinder must be marked

with the following information:

(i) The DOT specification marking

must appear first, followed immediately

by the service pressure. For example,

DOT–3A1800.

(ii) The serial number must be placed

just below or immediately following the

DOT specification marking.

(iii) A symbol (letters) must be placed

just below, immediately before or

following the serial number. Other

variations in sequence of markings are

authorized only when necessitated by a

lack of space. The symbol and numbers

must be those of the manufacturer. The

symbol must be registered with the

Associate Administrator; duplications

are not authorized.

(iv) The inspector’s official mark and

date of test (such as 5–95 for May 1995)

must be placed near the serial number.

This information must be placed so that

dates of subsequent tests can be easily

added. An example of the markings

prescribed in this paragraph (f)(1) is as

follows:

DOT–3A1800

1234

XY

AB 5–95

Or;

DOT–3A1800–1234–XY

AB 5–95

Where:

DOT–3A=specification number

1800=service pressure

1234=serial number

xy=symbol of manufacturer

AB=inspector’s mark

5–95=date of test

(2) Additional required marking must

be applied to the cylinder as follows:

(i) The word ‘‘spun’’ or ‘‘plug’’ must

be placed near the DOT specification

marking when an end closure in the

finished cylinder has been welded by

the spinning process, or effected by

plugging.

(ii) As prescribed in specification 3HT

(§ 178.44) or 3T (§ 178.45), if applicable.

(3) Marking exceptions.

(i) A DOT 3E cylinder is not required

to be marked with the inspector mark.

(ii) An identifying lot number may be

marked on the cylinder in place of a

serial number for cylinders not over 2

inches outside diameter or for cylinders

with a volumetric capacity not

exceeding 60 cubic inches. Each lot

shall not have over 500 cylinders.

(4) Unless otherwise specified in the

applicable specification, the markings

on each cylinder must be stamped

plainly and permanently on the

shoulder, top head, or neck.

(5) The size of each marking must be

at least 0.25 inch or as space permits.

(6) Other markings are authorized

provided they are made in low stress

areas other than the side wall and are

not of a size and depth that will create

harmful stress concentrations. Such

marks may not conflict with any DOT

required markings.

(g) Inspector’s report. Each inspector

shall prepare a report containing, at a

minimum, the applicable information

listed in CGA Pamphlet C–11 or, until

October 1, 1997, in accordance with the

applicable test report requirements of

this subchapter in effect on September

30, 1996. Any additional information or

markings that are required by the

applicable specification must be shown

on the test report. The signature of the

inspector on the reports certifies that the

processes of manufacture and heat

treatment of cylinders were observed

and found satisfactory.

(h) Report retention. The

manufacturer of the cylinders shall

retain the reports required by this

subpart for 15 years from the original

test date of the cylinder.

§ 178.36 Specification 3A and 3AX

seamless steel cylinders.

(a) Type size and service pressure. In

addition to the requirements of § 178.35,

cylinders must conform to the

following:

(1) A DOT–3A cylinder is a seamless

steel cylinder with a water capacity

(nominal) not over 1,000 pounds and a

service pressure of at least 150 pounds

per square inch.

(2) A DOT–3AX is a seamless

stainless steel cylinder with a water

capacity not less than 1,000 pounds and

a service pressure of at least 500 pounds

per square inch, conforming to the

following requirements:

(i) Assuming the cylinder is to be

supported horizontally at its two ends

only and to be uniformly loaded over its

entire length consisting of the weight

per unit of length of the straight

cylindrical portion filled with water and

compressed to the specified test

pressure; the sum of two times the

maximum tensile stress in the bottom

fibers due to bending, plus that in the

same fibers (longitudinal stress), due to

hydrostatic test may not exceed 80
25944 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

percent of the minimum yield strength

of the steel at such maximum stress.

Wall thickness must be increased when

necessary to meet the requirement.

(ii) To calculate the maximum

longitudinal tensile stress due to

bending, the following formula must be

used:

S=Mc/I

(iii) To calculate the maximum

longitudinal tensile stress due to

hydrostatic test pressure, the following

formula must be used:

S=A1P/A2

where:

S=tensile stress—p.s.i.;

M=bending moment-inch pounds—

(wl2)/8;

w=weight per inch of cylinder filled

with water;

l=length of cylinder-inches;

c=radius (D)/(2) of cylinder-inches;

I=moment of inertia—0.04909 (D4¥d4)

inches fourth;

D=outside diameter-inches;

d=inside diameter-inches;

A1=internal area in cross section of

cylinder-square inches;

A2=area of metal in cross section of

cylinder-square inches;

P=hydrostatic test pressure-p.s.i.

(b) Steel. Open-hearth or electric steel

of uniform quality must be used.

Content percent may not exceed the

following: Carbon, 0.55; phosphorous,

0.045; sulphur, 0.050.

(c) Identification of material. Material

must be identified by any suitable

method, except that plates and billets

for hot-drawn cylinders must be marked

with the heat number.

(d) Manufacture. Cylinders must be

manufactured using equipment and

processes adequate to ensure that each

cylinder produced conforms to the

requirements of this subpart. No fissure

or other defect is permitted that is likely

to weaken the finished cylinder

appreciably. A reasonably smooth and

uniform surface finish is required. If not

originally free from such defects, the

surface may be machined or otherwise

treated to eliminate these defects. The

thickness of the bottoms of cylinders

welded or formed by spinning is, under

no condition, to be less than two times

the minimum wall thickness of the

cylindrical shell; such bottom

thicknesses must be measured within an

area bounded by a line representing the

points of contact between the cylinder

and floor when the cylinder is in a

vertical position.

(e) Welding or brazing. Welding or

brazing for any purpose whatsoever is

prohibited except as follows:

(1) Welding or brazing is authorized

for the attachment of neckrings and

footrings which are non-pressure parts

and only to the tops and bottoms of

cylinders having a service pressure of

500 pounds per square inch or less.

Cylinders, neckrings, and footrings must

be made of weldable steel, the carbon

content of which may not exceed 0.25

percent except in the case of 4130X steel

which may be used with proper welding

procedures.

(2) As permitted in paragraph (d) of

this section.

(3) Cylinders used solely in

anhydrous ammonia service may have a

1⁄2 inch diameter bar welded within

their concave bottoms.

(f) Wall thickness. For cylinders with

service pressure less than 900 pounds,

the wall stress may not exceed 24,000

pounds per square inch. A minimum

wall thickness of 0.100 inch is required

for any cylinder over 5 inches outside

diameter. Wall stress calculation must

be made by using the following formula:

S=[P(1.3D2+0.4d2)]/(D2¥d2)

Where:

S=wall stress in pounds per square inch;

P=minimum test pressure prescribed for

water jacket test or 450 pounds per

square inch whichever is the

greater;

D=outside diameter in inches;

d=inside diameter in inches.

(g) Heat treatment. The completed

cylinder must be uniformly and

properly heat-treated prior to tests.

(h) Openings in cylinders and

connections (valves, fuse plugs, etc.) for

those openings. Threads are required on

openings.

(1) Threads must be clean cut, even,

without checks, and to gauge.

(2) Taper threads, when used, must be

of length not less than as specified for

American Standard taper pipe threads.

(3) Straight threads having at least 6

engaged threads are authorized. Straight

threads must have a tight fit and

calculated shear strength of at least 10

times the test pressure of the cylinder.

Gaskets, adequate to prevent leakage,

are required.

(i) Hydrostatic test. Each cylinder

must successfully withstand a

hydrostatic test, as follows:

(1) The test must be by water-jacket,

or other suitable methods, operated so

as to obtain accurate data. The pressure

gauge must permit reading to an

accuracy of 1 percent. The expansion

gauge must permit reading of total

expansion to an accuracy of either 1

percent or 0.1 cubic centimeter.

(2) Pressure must be maintained for at

least 30 seconds and sufficiently longer

to ensure complete expansion. Any

internal pressure applied after heattreatment and previous to the official

test may not exceed 90 percent of the

test pressure. If, due to failure of the test

apparatus the test pressure cannot be

maintained the test may be repeated at

a pressure increased by 10 percent or

100 pounds per square inch, whichever

is the lower.

(3) Permanent, volumetric expansion

may not exceed 10 percent of the total

volumetric expansion at test pressure.

(4) Each cylinder must be tested to at

least 5⁄3 times service pressure.

(j) Flattening test. A flattening test

must be performed on one cylinder

taken at random out or each lot of 200

or less, by placing the cylinder between

wedge shaped knife edges having a 60°

included angle, rounded to 1⁄2-inch

radius. The longitudinal axis of the

cylinder must be at a 90-degree angle to

knife edges during the test. For lots of

30 or less, flattening tests are authorized

to be made on a ring at least 8 inches

long cut from each cylinder and

subjected to same heat treatment as the

finished cylinder.

(k) Physical test. A physical test must

be conducted to determine yield

strength, tensile strength, elongation,

and reduction of area of material as

follows:

(1) The test is required on 2

specimens cut from 1 cylinder taken at

random out of each lot of 200 or less.

For lots of 30 or less, physical tests are

authorized to be made on a ring at least

8 inches long cut from each cylinder

and subjected to same heat treatment as

the finished cylinder.

(2) Specimens must conform to the

following:

(i) Gauge length of 8 inches with a

width of not over 11⁄2 inches, a gauge

length of 2 inches with a width of not

over 11⁄2 inches, or a gauge length of at

least 24 times thickness with width not

over 6 times thickness is authorized

when cylinder wall is not over 3⁄16 inch

thick.

(ii) The specimen, exclusive of grip

ends, may not be flattened. Grip ends

may be flattened to within 1 inch of

each end of the reduced section.

(iii) When size of cylinder does not

permit securing straight specimens, the

specimens may be taken in any location

or direction and may be straightened or

flattened cold, by pressure only, not by

blows. When specimens are so taken

and prepared, the inspector’s report

must show in connection with record of

physical tests detailed information in

regard to such specimens.

(iv) Heating of a specimen for any

purpose is not authorized.

(3) The yield strength in tension must

be the stress corresponding to a

permanent strain of 0.2 percent of the
Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations 25945

gauge length. The following conditions

apply:

(i) The yield strength must be

determined by either the ‘‘offset’’

method or the ‘‘extension under load’’

method as prescribed in ASTM

Standard E8.

(ii) In using the ‘‘extension under

load’’ method, the total strain (or

‘‘extension under load’’) corresponding

to the stress at which the 0.2-percent

permanent strain occurs may be

determined with sufficient accuracy by

calculating the elastic extension of the

gauge length under appropriate load and

adding thereto 0.2 percent of the gauge

length. Elastic extension calculations

must be based on an elastic modulus of

30,000,000. In the event of controversy

the entire stress-strain diagram must be

plotted and the yield strength

determined from the 0.2 percent offset.

(iii) For the purpose of strain

measurement, the initial strain must be

set while the specimen is under a stress

of 12,000 pounds per square inch and

the strain indicator reading must be set

at the calculated corresponding strain.

(iv) Cross-head speed of the testing

machine may not exceed 1⁄8 inch per

minute during yield strength

determination.

(l) Acceptable results for physical and

flattening tests. Either of the following

is an acceptable result:

(1) An elongation at least 40 percent

for a 2-inch gauge length or at least 20

percent in other cases and yield strength

not over 73 percent of tensile strength.

In this instance, the flattening test is not

required.

(2) An elongation at least 20 percent

for a 2-inch gauge length or 10 percent

in other cases and a yield strength not

over 73 percent of tensile strength. In

this instance, the flattening test is

required, without cracking, to 6 times

the wall thickness.

(m) Leakage test. All spun cylinders

and plugged cylinders must be tested for

leakage by gas or air pressure after the

bottom has been cleaned and is free

from all moisture subject to the

following conditions and limitations:

(1) Pressure, approximately the same

as but no less than service pressure,

must be applied to one side of the

finished bottom over an area of at least

1⁄16 of the total area of the bottom but

not less than 3⁄4 inch in diameter,

including the closure, for at least 1

minute, during which time the other

side of the bottom exposed to pressure

must be covered with water and closely

examined for indications of leakage.

Except as provided in paragraph (n) of

this section, a cylinder that is leaking

must be rejected.

(2) A spun cylinder is one in which

an end closure in the finished cylinder

has been welded by the spinning

process.

(3) A plugged cylinder is one in

which a permanent closure in the

bottom of a finished cylinder has been

effected by a plug.

(4) As a safety precaution, if the

manufacturer elects to make this test

before the hydrostatic test, the

manufacturer should design the test

apparatus so that the pressure is applied

to the smallest area practicable, around

the point of closure, and so as to use the

smallest possible volume of air or gas.

(n) Rejected cylinders. Reheat

treatment is authorized for rejected

cylinders. Subsequent thereto, cylinders

must pass all prescribed tests to be

acceptable. Repair by welding or

spinning is not authorized. Spun

cylinders rejected under the provisions

of paragraph (m) of this section may be

removed from the spun cylinder

category by drilling to remove defective

material, tapping and plugging.

§ 178.37 Specification 3AA and 3AAX

seamless steel cylinders.

(a) Type, size and service pressure. In

addition to the requirements of § 178.35,

cylinders must conform to the

following:

(1) A DOT–3AA cylinder is a seamless

steel cylinder with a water capacity

(nominal) of not over 1,000 pounds and

a service pressure of at least 150 pounds

per square inch.

(2) A DOT–3AAX cylinder is a

seamless steel cylinder with a water

capacity of not less than 1,000 pounds

and a service pressure of at least 500

pounds per square inch, conforming to

the following requirements:

(i) Assuming the cylinder is to be

supported horizontally at its two ends

only and to be uniformly loaded over its

entire length consisting of the weight

per unit of length of the straight

cylindrical portion filled with water and

compressed to the specified test

pressure; the sum of two times the

maximum tensile stress in the bottom

fibers due to bending, plus that in the

same fibers (longitudinal stress), due to

hydrostatic test pressure may not exceed

80 percent of the minimum yield

strength of the steel at such maximum

stress. Wall thickness must be increased

when necessary to meet the

requirement.

(ii) To calculate the maximum tensile

stress due to bending, the following

formula must be used:

S=Mc/I

(iii) To calculate the maximum

longitudinal tensile stress due to

hydrostatic test pressure, the following

formula must be used:

S=A1P/A2

Where:

S=tensile stress-p.s.i.;

M=bending moment-inch pounds (wl2)/

8;

w=weight per inch of cylinder filled

with water;

l=length of cylinder-inches;

c=radius (D)/(2) of cylinder-inches;

I=moment of inertia-0.04909 (D4¥d4)

inches fourth;

D=outside diameter-inches;

d=inside diameter-inches;

A1=internal area in cross section of

cylinder-square inches;

A2=area of metal in cross section of

cylinder-square inches;

P=hydrostatic test pressure-p.s.i.

(b) Authorized steel. Open-hearth,

basic oxygen, or electric steel of uniform

quality must be used. A heat of steel

made under the specifications in Table

1 of this paragraph (b), check chemical

analysis of which is slightly out of the

specified range, is acceptable, if

satisfactory in all other respects,

provided the tolerances shown in Table

2 of this paragraph (b) are not exceeded.

When a carbon-boron steel is used, a

hardenability test must be performed on

the first and last ingot of each heat of

steel. The results of this test must be

recorded on the Record of Chemical

Analysis of Material for Cylinders

required by § 178.35. This hardness test

must be made 5⁄16-inch from the

quenched end of the Jominy quench bar

and the hardness must be at least Rc 33

and no more than Rc 53. The following

chemical analyses are authorized:

TABLE 1.—AUTHORIZED MATERIALS

Designation 4130X (percent)

(see Note 1)

NE–8630 (percent)

(see Note 1)

9115 (percent)

(see Note 1)

9125 (percent)

(see Note 1)

Carbon-boron

(percent)

Inter- mediate manganese

(percent)

Carbon ......................... 0.25/0.35 .............. 0.28/0.33 .............. 0.10/0.20 .............. 0.20/0.30 .............. 0.27–0.37 ............. 0.40 max.
25946 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

TABLE 1.—AUTHORIZED MATERIALS—Continued

Designation 4130X (percent)

(see Note 1)

NE–8630 (percent)

(see Note 1)

9115 (percent)

(see Note 1)

9125 (percent)

(see Note 1)

Carbon-boron

(percent)

Inter- mediate manganese

(percent)

Manganese .................. 0.40/0.90 .............. 0.70/0.90 .............. 0.50/0.75 .............. 0.50/0.75 .............. 0.80–1.40 ............. 1.35/1.65.

Phosphorus .................. 0.04 max .............. 0.04 max .............. 0.04 max .............. 0.04 max .............. 0.035 max ............ 0.04 max.

Sulfur ............................ 0.05 max .............. 0.04 max .............. 0.04 max .............. 0.04 max .............. 0.045 max ............ 0.05 max.

Silicon .......................... 0.15/0.35 .............. 0.20/0.35 .............. 0.60/0.90 .............. 0.60/0.90 .............. 0.3 max. ............... 0.10/0.30.

Chromium ..................... 0.80/1.10 .............. 0.40/0.60 .............. 0.50/0.65 .............. 0.50/0.65.

Molybdenum ................. 0.15/0.25 .............. 0.15/0.25

Zirconium ..................... .............................. .............................. 0.05/0.15 .............. 0.05/0.15

Nickel ........................... .............................. 0.40/0.70.

Boron ........................... .............................. .............................. .............................. .............................. 0.0005/0.003.

NOTE 1: This designation may not be restrictive and the commercial steel is limited in analysis as shown in this Table.

TABLE 2.—CHECK ANALYSIS TOLERANCES

Element Limit or maximum specified

(percent)

Tolerance (percent) over

the maximum limit or

under the minimum limit

Under minimum limitOver maximum limit

Carbon ................................................................. To 0.15 incl .................................................................................... 0.02 0.03

Over 0.15 to 0.40 incl .................................................................... .03 .04

Manganese .......................................................... To 0.60 incl .................................................................................... .03 .03

Over 0.60 to 1.15 incl .................................................................... 0.04 0.04

Over 1.15 to 2.50 incl .................................................................... 0.05 0.05

Phosphorus1 ........................................................ All ranges ...................................................................................... .................... .01

Sulphur ................................................................. All ranges ...................................................................................... .................... .01

Silicon ................................................................... To 0.30 incl .................................................................................... .02 .03

Over 0.30 to 1.00 incl .................................................................... .05 .05

Nickel ................................................................... To 1.00 incl .................................................................................... .03 .03

Chromium ............................................................. To 0.90 incl .................................................................................... .03 .03

0.90 to 2.90 incl ............................................................................. .05 .05

Molybdenum ......................................................... To 0.20 incl .................................................................................... .01 .01

Over 0.20 to 0.40 .......................................................................... .02 .02

Zirconium ............................................................. All ranges ...................................................................................... .01 .05

1 Rephosphorized steels not subject to check analysis for phosphorus.

(c) Identification of material. Material

must be identified by any suitable

method except that plates and billets for

hot-drawn cylinders must be marked

with the heat number.

(d) Manufacture. Cylinders must be

manufactured using equipment and

processes adequate to ensure that each

cylinder produced conforms to the

requirements of this subpart. No fissure

or other defects is permitted that is

likely to weaken the finished cylinder

appreciably. A reasonably smooth and

uniform surface finish is required. If not

originally free from such defects, the

surface may be machined or otherwise

treated to eliminate these defects. The

thickness of the bottoms of cylinders

welded or formed by spinning is, under

no condition, to be less than two times

the minimum wall thickness of the

cylindrical shell; such bottom

thicknesses must be measured within an

area bounded by a line representing the

points of contact between the cylinder

and floor when the cylinder is in a

vertical position.

(e) Welding or brazing. Welding or

brazing for any purpose whatsoever is

prohibited except as follows:

(1) Welding or brazing is authorized

for the attachment of neckrings and

footrings which are non-pressure parts,

and only to the tops and bottoms of

cylinders having a service pressure of

500 pounds per square inch or less.

Cylinders, neckrings, and footrings must

be made of weldable steel, the carbon

content of which may not exceed 0.25

percent except in the case of 4130X steel

which may be used with proper welding

procedure.

(2) As permitted in paragraph (d) of

this section.

(f) Wall thickness. The thickness of

each cylinder must conform to the

following:

(1) For cylinders with a service

pressure of less than 900 pounds, the

wall stress may not exceed 24,000

pounds per square inch. A minimum

wall thickness of 0.100 inch is required

for any cylinder with an outside

diameter of over 5 inches.

(2) For cylinders with service pressure

of 900 p.s.i. or more the minimum wall

must be such that the wall stress at the

minimum specified test pressure may

not exceed 67 percent of the minimum

tensile strength of the steel as

determined from the physical tests

required in paragraphs (k) and (l) of this

section and must be not over 70,000

p.s.i.

(3) Calculation must be made by the

formula:

S=[P(1.3D2+0.4d2)]/(D2¥d2)

Where:

S=wall stress in pounds per square inch;

P=minimum test pressure prescribed for

water jacket test or 450 pounds per

square inch whichever is the

greater;

D=outside diameter in inches;

d=inside diameter in inches.

(g) Heat treatment. The completed

cylinders must be uniformly and

properly heat treated prior to tests. Heat

treatment of cylinders of the authorized

analyses must be as follows:
Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations 25947

(1) All cylinders must be quenched by

oil, or other suitable medium except as

provided in paragraph (g)(5) of this

section.

(2) The steel temperature on

quenching must be that recommended

for the steel analysis, but may not

exceed 1750 °F.

(3) All steels must be tempered at a

temperature most suitable for that steel.

(4) The minimum tempering

temperature may not be less than 1000

°F except as noted in paragraph (1)(vi)

of this section.

(5) Steel 4130X may be normalized at

a temperature of 1650 °F instead of

being quenched and cylinders so

normalized need not be tempered.

(6) Intermediate manganese steels

may be tempered at temperatures not

less than 1150 °F., and after heat

treating each cylinder must be

submitted to a magnetic test to detect

the presence of quenching cracks.

Cracked cylinders must be rejected and

destroyed.

(7) Except as otherwise provided in

paragraph (g)(6) of this section, all

cylinders, if water quenched or

quenched with a liquid producing a

cooling rate in excess of 80 percent of

the cooling rate of water, must be

inspected by the magnetic particle, dye

penetrant or ultrasonic method to detect

the presence of quenching cracks. Any

cylinder designed to the requirements

for specification 3AA and found to have

a quenching crack must be rejected and

may not be requalified. Cylinders

designed to the requirements for

specification 3AAX and found to have

cracks must have cracks removed to

sound metal by mechanical means.

Such specification 3AAX cylinders will

be acceptable if the repaired area is

subsequently examined to assure no

defect, and it is determined that design

thickness requirements are met.

(h) Openings in cylinders and

connections (valves, fuse plugs, etc.) for

those openings. Threads are required on

openings.

(1) Threads must be clean cut, even,

without checks, and to gauge.

(2) Taper threads, when used, must be

of a length not less than as specified for

American Standard taper pipe threads.

(3) Straight threads having at least 6

engaged threads are authorized. Straight

threads must have a tight fit and a

calculated shear strength of at least 10

times the test pressure of the cylinder.

Gaskets, adequate to prevent leakage,

are required.

(i) Hydrostatic test. Each cylinder

must successfully withstand a

hydrostatic test as follows:

(1) The test must be by water-jacket,

or other suitable method, operated so as

to obtain accurate data. The pressure

gauge must permit reading to an

accuracy of 1 percent. The expansion

gauge must permit reading of total

expansion to an accuracy of either 1

percent or 0.1 cubic centimeter.

(2) Pressure must be maintained for at

least 30 seconds and sufficiently longer

to ensure complete expansion. Any

internal pressure applied after heattreatment and previous to the official

test may not exceed 90 percent of the

test pressure. If, due to failure of the test

apparatus, the test pressure cannot be

maintained, the test may be repeated at

a pressure increased by 10 percent or

100 pounds per square inch, whichever

is the lower.

(3) Permanent volumetric expansion

may not exceed 10 percent of total

volumetric expansion at test pressure.

(4) Each cylinder must be tested to at

least 5⁄3 times the service pressure.

(j) Flattening test. A flattening test

must be performed on one cylinder

taken at random out of each lot of 200

or less, by placing the cylinder between

wedge shaped knife edges having a 60°

included angle, rounded to 1⁄2-inch

radius. The longitudinal axis of the

cylinder must be at a 90-degree angle to

knife edges during the test. For lots of

30 or less, flattening tests are authorized

to be made on a ring at least 8 inches

long cut from each cylinder and

subjected to same heat treatment as the

finished cylinder.

(k) Physical test. A physical test must

be conducted to determine yield

strength, tensile strength, elongation,

and reduction of area of material as

follows:

(1) The test is required on 2

specimens cut from 1 cylinder taken at

random out of each lot of 200 or less.

For lots of 30 or less, physical tests are

authorized to be made on a ring at least

8 inches long cut from each cylinder

and subjected to the same heat

treatment as the finished cylinder.

(2) Specimens must conform to the

following:

(i) Gauge length of 8 inches with a

width of not over 11⁄2 inches, a gauge

length of 2 inches with a width of not

over 11⁄2 inches, or a gauge length of at

least 24 times the thickness with width

not over 6 times thickness when the

thickness of the cylinder wall is not

over 3⁄16 inch.

(ii) The specimen, exclusive of grip

ends, may not be flattened. Grip ends

may be flattened to within 1 inch of

each end of the reduced section.

(iii) When size of cylinder does not

permit securing straight specimens, the

specimens may be taken in any location

or direction and may be straightened or

flattened cold, by pressure only, not by

blows. When specimens are so taken

and prepared, the inspector’s report

must show in connection with record of

physical tests detailed information in

regard to such specimens.

(iv) Heating of a specimen for any

purpose is not authorized.

(3) The yield strength in tension must

be the stress corresponding to a

permanent strain of 0.2 percent of the

gauge length. The following conditions

apply:

(i) The yield strength must be

determined by either the ‘‘offset’’

method or the ‘‘extension under load’’

method as prescribed in ASTM

Standard E8.

(ii) In using the ‘‘extension under

load’’ method, the total strain (or

‘‘extension under load’’) corresponding

to the stress at which the 0.2 percent

permanent strain occurs may be

determined with sufficient accuracy by

calculating the elastic extension of the

gauge length under appropriate load and

adding thereto 0.2 percent of the gauge

length. Elastic extension calculations

must be based on an elastic modulus of

30,000,000. In the event of controversy,

the entire stress-strain diagram must be

plotted and the yield strength

determined from the 0.2 percent offset.

(iii) For the purpose of strain

measurement, the initial strain must be

set while the specimen is under a stress

of 12,000 pounds per square inch, the

strain indicator reading being set at the

calculated corresponding strain.

(iv) Cross-head speed of the testing

machine may not exceed 1⁄8 inch per

minute during yield strength

determination.

(l) Acceptable results for physical and

flattening tests. An acceptable result for

physical and flattening tests is

elongation at least 20 percent for 2

inches of gauge length or at least 10

percent in other cases. Flattening is

required without cracking to 6 times the

wall thickness of the cylinder.

(m) Leakage test. All spun cylinders

and plugged cylinders must be tested for

leakage by gas or air pressure after the

bottom has been cleaned and is free

from all moisture. Pressure,

approximately the same as but no less

than the service pressure, must be

applied to one side of the finished

bottom over an area of at least 1⁄16 of the

total area of the bottom but not less than

3⁄4 inch in diameter, including the

closure, for at least one minute, during

which time the other side of the bottom

exposed to pressure must be covered

with water and closely examined for

indications of leakage. Except as

provided in paragraph (n) of this

section, a cylinder must be rejected if

there is any leaking.
25948 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

(1) A spun cylinder is one in which

an end closure in the finished cylinder

has been welded by the spinning

process.

(2) A plugged cylinder is one in

which a permanent closure in the

bottom of a finished cylinder has been

effected by a plug.

(3) As a safety precaution, if the

manufacturer elects to make this test

before the hydrostatic test, the

manufacturer should design the test

apparatus so that the pressure is applied

to the smallest area practicable, around

the point of closure, and so as to use the

smallest possible volume of air or gas.

(n) Rejected cylinders. Reheat

treatment is authorized for rejected

cylinders. Subsequent thereto, cylinders

must pass all prescribed tests to be

acceptable. Repair by welding or

spinning is not authorized. Spun

cylinders rejected under the provision

of paragraph (m) of this section may be

removed from the spun cylinder

category by drilling to remove defective

material, tapping and plugging.

§ 178.38 Specification 3B seamless steel

cylinders.

(a) Type, size, and service pressure. A

DOT 3B cylinder is seamless steel

cylinder with a water capacity

(nominal) of not over 1,000 pounds and

a service pressure of at least 150 to not

over 500 pounds per square inch.

(b) Steel. Open-hearth or electric steel

of uniform quality must be used.

Content percent may not exceed the

following: carbon, 0.55; phosphorus,

0.045; sulphur, 0.050.

(c) Identification of material. Material

must be identified by any suitable

method except that plates and billets for

hot-drawn cylinders must be marked

with the heat number.

(d) Manufacture. Cylinders must be

manufactured using equipment and

processes adequate to ensure that each

cylinder produced conforms to the

requirements of this subpart. No fissure

or other defect is permitted that is likely

to weaken the finished cylinder

appreciably. A reasonably smooth and

uniform surface finish is required. If not

originally free from such defects, the

surface may be machined or otherwise

treated to eliminate these defects. The

thickness of the bottoms of cylinders

welded or formed by spinning is, under

no condition, to be less than two times

the minimum wall thickness of the

cylindrical shell; such bottom

thicknesses to be measured within an

area bounded by a line representing the

points of contact between the cylinder

and floor when the cylinder is in a

vertical position.

(e) Welding or brazing. Welding or

brazing for any purpose whatsoever is

prohibited except as follows:

(1) Welding or brazing is authorized

for the attachment of neckrings and

footrings which are non-pressure parts,

and only to the tops and bottoms of

cylinders having a service pressure of

500 pounds per square inch or less.

Cylinders, neckrings, and footrings must

be made of weldable steel, carbon

content of which may not exceed 0.25

percent except in the case of 4130X steel

which may be used with proper welding

procedure.

(2) As permitted in paragraph (d) of

this section.

(f) Wall thickness. The wall stress may

not exceed 24,000 pounds per square

inch. The minimum wall thickness is

0.090 inch for any cylinder with an

outside diameter of 6 inches.

Calculation must be made by the

following formula:

S=[P(1.3D2+0.4d2)]/(D2¥d2)

Where:

S=wall stress in pounds per square inch;

P=at least two times service pressure or

450 pounds per square inch,

whichever is the greater;

D=outside diameter in inches;

d=inside diameter in inches.

(g) Heat treatment. The completed

cylinders must be uniformly and

properly heat-treated prior to tests.

(h) Openings in cylinders and

connections (valves, fuse plugs, etc.) for

those openings. Threads, conforming to

the following, are required on all

openings:

(1) Threads must be clean cut, even,

without checks, and to gauge.

(2) Taper threads when used, must be

of a length not less than as specified for

American Standard taper pipe threads.

(3) Straight threads having at least 4

engaged threads are authorized. Straight

threads must have a tight fit, and

calculated shear strength at least 10

times the test pressure of the cylinder.

Gaskets, adequate to prevent leakage,

are required.

(i) Hydrostatic test. Cylinders must

successfully withstand a hydrostatic

test, as follows:

(1) The test must be by water-jacket,

or other suitable method, operated so as

to obtain accurate data. The pressure

gauge must permit reading to an

accuracy of 1 percent. The expansion

gauge must permit reading of total

expansion to an accuracy either of 1

percent or 0.1 cubic centimeter.

(2) Pressure must be maintained for at

least 30 seconds and sufficiently longer

to insure complete expansion. Any

internal pressure applied after heattreatment and previous to the official

test may not exceed 90 percent of the

test pressure. If, due to failure of the test

apparatus, the test pressure cannot be

maintained, the test may be repeated at

a pressure increased by 10 percent or

100 pounds per square inch, whichever

is the lower.

(3) Permanent volumetric expansion

may not exceed 10 percent of total

volumetric expansion at test pressure.

(4) Cylinders must be tested as

follows:

(i) Each cylinder; to at least 2 times

service pressure; or

(ii) 1 cylinder out of each lot of 200

or less; to at least 3 times service

pressure. Others must be examined

under pressure of 2 times service

pressure and show no defect.

(j) Flattening test. A flattening test

must be performed on one cylinder

taken at random out or each lot of 200

or less, by placing the cylinder between

wedge shaped knife edges having a 60°

included angle, rounded to 1⁄2-inch

radius. The longitudinal axis of the

cylinder must be at a 90-degree angle to

knife edges during the test. For lots of

30 or less, flattening tests are authorized

to be made on a ring at least 8 inches

long cut from each cylinder and

subjected to same heat treatment as the

finished cylinder.

(k) Physical test. A physical test must

be conducted to determine yield

strength, tensile strength, elongation,

and reduction of area of material, as

follows:

(1) The test is required on 2

specimens cut from 1 cylinder taken at

random out of each lot of 200 or less.

For lots of 30 or less, physical tests are

authorized to be made on a ring at least

8 inches long cut from each cylinder

and subjected to same heat treatment as

the finished cylinder.

(2) Specimens must conform to the

following:

(i) Gauge length of 8 inches with a

width of not over 11⁄2 inches; or a gauge

length of 2 inches with a width of not

over 11⁄2 inches; or a gauge length at

least 24 times the thickness with a

width not over 6 times thickness is

authorized when a cylinder wall is not

over 3⁄16 inch thick.

(ii) The specimen, exclusive of grip

ends, may not be flattened. Grip ends

may be flattened to within one inch of

each end of the reduced section.

(iii) When size of cylinder does not

permit securing straight specimens, the

specimens may be taken in any location

or direction and may be straightened or

flattened cold, by pressure only, not by

blows. When specimens are so taken

and prepared, the inspector’s report

must show in connection with record of
Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations 25949

physical tests detailed information in

regard to such specimens.

(iv) Heating of a specimen for any

purpose is not authorized.

(3) The yield strength in tension must

be the stress corresponding to a

permanent strain of 0.2 percent of the

gauge length. The following conditions

apply:

(i) The yield strength must be

determined by either the ‘‘offset’’

method or the ‘‘extension under load’’

method as prescribed in ASTM

Standard E8.

(ii) In using the ‘‘extension under

load’’ method, the total strain (or

‘‘extension under load’’) corresponding

to the stress at which the 0.2 percent

permanent strain occurs may be

determined with sufficient accuracy by

calculating the elastic extension of the

gauge length under appropriate load and

adding thereto 0.2 percent of the gauge

length. Elastic extension calculations

must be based on an elastic modulus of

30,000,000. In the event of controversy,

the entire stress-strain diagram must be

plotted and the yield strength

determined from the 0.2 percent offset.

(iii) For the purpose of strain

measurement, the initial strain must be

set while the specimen is under a stress

of 12,000 pounds per square inch, and

the strain indicator reading being set at

the calculated corresponding strain.

(iv) Cross-head speed of the testing

machine may not exceed 1⁄8 inch per

minute during yield strength

determination.

(l) Acceptable results for physical and

flattening tests. Either of the following

is an acceptable result:

(1) An elongation of at least 40

percent for a 2-inch gauge length or at

least 20 percent in other cases and yield

strength not over 73 percent of tensile

strength. In this instance, the flattening

test is not required.

(2) An elongation of at least 20

percent for a 2-inch gauge length or 10

percent in other cases and yield strength

not over 73 percent of tensile strength.

Flattening is required, without cracking,

to 6 times the wall thickness.

(m) Leakage test. All spun cylinders

and plugged cylinders must be tested for

leakage by gas or air pressure after the

bottom has been cleaned and is free

from all moisture, subject to the

following conditions and limitations:

(1) Pressure, approximately the same

as but no less than service pressure,

must be applied to one side of the

finished bottom over an area of at least

1⁄16 of the total area of the bottom but

not less than 3⁄4 inch in diameter,

including the closure, for at least one

minute, during which time the other

side of the bottom exposed to pressure

must be covered with water and closely

examined for indications of leakage.

Except as provided in paragraph (n) of

this section, a cylinder must be rejected

if there is any leaking.

(2) A spun cylinder is one in which

an end closure in the finished cylinder

has been welded by the spinning

process.

(3) A plugged cylinder is one in

which a permanent closure in the

bottom of a finished cylinder has been

effected by a plug.

(4) As a safety precaution, if the

manufacturer elects to make this test

before the hydrostatic test, he should

design his apparatus so that the pressure

is applied to the smallest area

practicable, around the point of closure,

and so as to use the smallest possible

volume of air or gas.

(n) Rejected cylinders. Reheat

treatment of rejected cylinders is

authorized. Subsequent thereto,

cylinders must pass all prescribed tests

to be acceptable. Repair by welding or

spinning is not authorized. Spun

cylinders rejected under the provisions

of paragraph (m) of this section may be

removed from the spun cylinder

category by drilling to remove defective

material, tapping and plugging.

(o) Marking. Markings may be

stamped into the sidewalls of cylinders

having a service pressure of 150 psi if

all of the following conditions are met:

(1) Wall stress at test pressure may not

exceed 24,000 psi.

(2) Minimum wall thickness must be

not less than 0.090 inch.

(3) Depth of stamping must be no

greater than 15 percent of the minimum

wall thickness, but may not exceed

0.015 inch.

(4) Maximum outside diameter of

cylinder may not exceed 5 inches.

(5) Carbon content of cylinder may

not exceed 0.25 percent. If the carbon

content exceeds 0.25 percent, the

complete cylinder must be normalized

after stamping.

(6) Stamping must be adjacent to the

top head.

§ 178.39 Specification 3BN seamless

nickel cylinders.

(a) Type, size and service pressure. A

DOT 3BN cylinder is a seamless nickel

cylinder with a water capacity

(nominal) not over 125 pounds water

capacity (nominal) and a service

pressure at least 150 to not over 500

pounds per square inch.

(b) Nickel. The percentage of nickel

plus cobalt must be at least 99.0 percent.

(c) Identification of material. The

material must be identified by any

suitable method except that plates and

billets for hot-drawn cylinders must be

marked with the heat number.

(d) Manufacture. Cylinders must be

manufactured using equipment and

processes adequate to ensure that each

cylinder produced conforms to the

requirements of this subpart. No defect

is permitted that is likely to weaken the

finished cylinder appreciably. A

reasonably smooth and uniform surface

finish is required. Cylinders closed in

by spinning process are not authorized.

(e) Welding or brazing. Welding or

brazing for any purpose whatsoever is

prohibited except that welding is

authorized for the attachment of

neckrings and footrings which are

nonpressure parts, and only to the tops

and bottoms of cylinders. Neckrings and

footrings must be of weldable material,

the carbon content of which may not

exceed 0.25 percent. Nickel welding rod

must be used.

(f) Wall thickness. The wall stress may

not exceed 15,000 pounds per square

inch. A minimum wall thickness of

0.100 inch is required for any cylinder

over 5 inches in outside diameter. Wall

stress calculation must be made by

using the following formula:

S=[P(1.3D2+0.4d2)]/(D2¥d2)

Where:

S=wall stress in pounds per square inch;

P=minimum test pressure prescribed for

water jacket test or 450 pounds per

square inch whichever is the

greater;

D=outside diameter in inches;

d=inside diameter in inches.

(g) Heat treatment. The completed

cylinders must be uniformly and

properly heat-treated prior to tests.

(h) Openings in cylinders and

connections (valves, fuse plugs, etc.) for

those openings. Threads conforming to

the following are required on openings:

(1) Threads must be clean cut, even,

without checks, and to gauge.

(2) Taper threads, when used, to be of

length not less than as specified for

American Standard taper pipe threads.

(3) Straight threads having at least 6

engaged threads are authorized. Straight

threads must have a tight fit and a

calculated shear strength of at least 10

times the test pressure of the cylinder.

Gaskets, adequate to prevent leakage,

are required.

(i) Hydrostatic test. Each cylinder

must successfully withstand a

hydrostatic test, as follows:

(1) The test must be by water-jacket,

or other suitable method, operated so as

to obtain accurate data. The pressure

gauge must permit reading to an

accuracy of 1 percent. The expansion

gauge must permit reading of total

expansion to an accuracy either of 1

percent or 0.1 cubic centimeter.

(2) Pressure must be maintained for at

least 30 seconds and sufficiently longer
25950 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

to ensure complete expansion. Any

internal pressure applied after heattreatment and previous to the official

test may not exceed 90 percent of the

test pressure. If, due to failure of the test

apparatus, the test pressure cannot be

maintained, the test may be repeated at

a pressure increased by 10 percent or

100 pounds per square inch, whichever

is the lower.

(3) Permanent volumetric expansion

may not exceed 10 percent of total

volumetric expansion at test pressure.

(4) Each cylinder must be tested to at

least 2 times service pressure.

(j) Flattening test. A flattening test

must be performed on one cylinder

taken at random out or each lot of 200

or less, by placing the cylinder between

wedge shaped knife edges having a 60°

included angle, rounded to 1⁄2-inch

radius. The longitudinal axis of the

cylinder must be at a 90-degree angle to

knife edges during the test. For lots of

30 or less, flattening tests are authorized

to be made on a ring at least 8 inches

long cut from each cylinder and

subjected to same heat treatment as the

finished cylinder.

(k) Physical test. A physical test must

be conducted to determine yield

strength, tensile strength, elongation,

and reduction of area of material, as

follows:

(1) The test is required on 2

specimens cut from 1 cylinder taken at

random out of each lot of 200 or less.

For lots of 30 or less, physical tests are

authorized to be made on a ring at least

8 inches long cut from each cylinder

and subjected to same heat treatment as

the finished cylinder.

(2) Specimens must conform to the

following:

(i) A gauge length of 8 inches with a

width of not over 11⁄2 inches, a gauge

length of 2 inches with a width of not

over 11⁄2 inches, or a gauge length of at

least 24 times the thickness with a

width not over 6 times thickness is

authorized when a cylinder wall is not

over 3⁄16 inch thick.

(ii) The specimen, exclusive of grip

ends, may not be flattened. Grip ends

may be flattened to within one inch of

each end of the reduced section.

(iii) When size of cylinder does not

permit securing straight specimens, the

specimens may be taken in any location

or direction and may be straightened or

flattened cold, by pressure only, not by

blows. When specimens are so taken

and prepared, the inspector’s report

must show in connection with record of

physical tests detailed information in

regard to such specimens.

(iv) Heating of a specimen for any

purpose is not authorized.

(3) The yield strength in tension must

be the stress corresponding to a

permanent strain of 0.2 percent of the

gauge length. The following conditions

apply:

(i) The yield strength must be

determined by either the ‘‘offset’’

method or the ‘‘extension under load’’

method as prescribed in ASTM

Standard E8.

(ii) In using the ‘‘extension under

load’’ method, the total strain (or

‘‘extension under load’’) corresponding

to the stress at which the 0.2 percent

permanent strain occurs may be

determined with sufficient accuracy by

calculating the elastic extension of the

gauge length under appropriate load and

adding thereto 0.2 percent of the gauge

length. Elastic extension calculations

must be based on an elastic modulus of

30,000,000. In the event of controversy,

the entire stress-strain diagram must be

plotted and the yield strength

determined from the 0.2 percent offset.

(iii) For the purpose of strain

measurement, the initial strain must be

set while the specimen is under a stress

of 12,000 pounds per square inch, and

the strain indicator reading must be set

at the calculated corresponding strain.

(iv) Cross-head speed of the testing

machine may not exceed 1⁄8 inch per

minute during yield strength

determination.

(l) Acceptable results for physical and

flattening tests. Either of the following

is an acceptable result:

(1) An elongation of at least 40

percent for a 2 inch gauge length or at

least 20 percent in other cases and yield

point not over 50 percent of tensile

strength. In this instance, the flattening

test is not required.

(2) An elongation of at least 20

percent for a 2 inch gauge length or 10

percent in other cases and a yield point

not over 50 percent of tensile strength.

Flattening is required, without cracking,

to 6 times the wall thickness.

(m) Rejected cylinders. Reheat

treatment is authorized for rejected

cylinders. Subsequent thereto, cylinders

must pass all prescribed tests to be

acceptable. Repair by welding is not

authorized.

§ 178.42 Specification 3E seamless steel

cylinders.

(a) Type, size, and service pressure. A

DOT 3E cylinder is a seamless steel

cylinder with an outside diameter not

greater than 2 inches nominal, a length

less than 2 feet and a service pressure

of 1,800 pounds per square inch.

(b) Steel. Open-hearth or electric steel

of uniform quality must be used.

Content percent may not exceed the

following: Carbon, 0.55; phosphorus,

0.045; sulphur, 0.050.

(c) Identification of steel. Materials

must be identified by any suitable

method.

(d) Manufacture. Cylinders must be

manufactured by best appliances and

methods. No defect is permitted that is

likely to weaken the finished cylinder

appreciably. A reasonably smooth and

uniform surface finish is required. The

thickness of the spun bottom is, under

no condition, to be less than two times

the minimum wall thickness of the

cylindrical shell; such bottom thickness

must be measured within an area

bounded by a line representing the

points of contact between the cylinder

and floor when the cylinder is in a

vertical position.

(e) Openings in cylinders and

connections (valves, fuse plugs, etc.) for

those openings. Threads conforming to

the following are required on openings.

(1) Threads must be clean cut, even,

without checks, and to gauge.

(2) Taper threads, when used, must be

of length not less than as specified for

American Standard taper pipe threads.

(3) Straight threads having at least 4

engaged threads are authorized. Straight

threads must have a tight fit and a

calculated shear strength of at least 10

times the test pressure of the cylinder.

Gaskets, adequate to prevent leakage,

are required.

(f) Hydrostatic test. Cylinders must be

tested as follows:

(1) One cylinder out of each lot of 500

or less must be subjected to a

hydrostatic pressure of 6,000 pounds

per square inch or higher.

(2) The cylinder referred to in

paragraph (f)(1) of this section must

burst at a pressure higher than 6,000

pounds per square inch without

fragmenting or otherwise showing lack

of ductility, or must hold a pressure of

12,000 pounds per square inch for 30

seconds without bursting. In which

case, it must be subjected to a flattening

test without cracking to six times wall

thickness between knife edges, wedge

shaped 60 degree angle, rounded out to

a 1⁄2 inch radius. The inspector’s report

must be suitably changed to show

results of latter alternate and flattening

test.

(3) Other cylinders must be examined

under pressure of at least 3,000 pounds

per square inch and not to exceed 4,500

pounds per square inch and show no

defect. Cylinders tested at a pressure in

excess of 3,600 pounds per square inch

must burst at a pressure higher than

7,500 pounds per square inch when

tested as specified in paragraph (f)(2) of

this section. The pressure must be

maintained for at least 30 seconds and
Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations 25951

sufficiently longer to ensure complete

examination.

(g) Leakage test. All spun cylinders

and plugged cylinders must be tested for

leakage by gas or air pressure after the

bottom has been cleaned and is free

from all moisture subject to the

following conditions and limitations:

(1) A pressure, approximately the

same as but not less than the service

pressure, must be applied to one side of

the finished bottom over an area of at

least 1⁄16 of the total area of the bottom

but not less than 3⁄4 inch in diameter,

including the closure, for at least one

minute, during which time the other

side of the bottom exposed to pressure

must be covered with water and closely

examined for indications of leakage.

Accept as provided in paragraph (h) of

this section, a cylinder must be rejected

if there is any leakage.

(2) A spun cylinder is one in which

an end closure in the finished cylinder

has been welded by the spinning

process.

(3) A plugged cylinder is one in

which a permanent closure in the

bottom of a finished cylinder has been

effected by a plug.

(4) As a safety precaution, if the

manufacturer elects to make this test

before the hydrostatic test, the

manufacturer shall design the test

apparatus so that the pressure is applied

to the smallest area practicable, around

the point of closure, and so as to use the

smallest possible volume of air or gas.

(h) Rejected cylinders. Reheat

treatment is authorized for rejected

cylinders. Subsequent thereto, cylinders

must pass all prescribed tests to be

acceptable. Repair by welding or

spinning is not authorized. Spun

cylinders rejected under the provisions

of paragraph (g) of this section may be

removed from the spun cylinder

category by drilling to remove defective

material, tapping and plugging.

(i) Marking. Markings required by

§ 178.35 must be stamped plainly and

permanently on the shoulder, top head,

neck or sidewall of each cylinder.

§ 178.44 Specification 3HT seamless steel

cylinders for aircraft use.

(a) Type, size and service pressure. A

DOT 3HT cylinder is a seamless steel

cylinder with a water capacity

(nominal) of not over 150 pounds and

a service pressure of at least 900 pounds

per square inch.

(b) Authorized steel. Open hearth or

electric furnace steel of uniform quality

must be used. A heat of steel made

under the specifications listed in Table

1 in this paragraph (b), check chemical

analysis of which is slightly out of the

specified range, is acceptable, if

satisfactory in all other respects,

provided the tolerances shown in Table

2 in this paragraph (b) are not exceeded.

Grain size 6 or finer according to ASTM

E 112. Steel of the following chemical

analysis is authorized:

TABLE 1.—AUTHORIZED MATERIALS

Designation AISI 4130

(percent)

Carbon .............................................................................................................................................................................................. 0.28/0.33

Manganese ....................................................................................................................................................................................... 0.40/0.60

Phosphorus ....................................................................................................................................................................................... 0.040 maximum

Sulfur ................................................................................................................................................................................................. 0.040 maximum

Silicon ................................................................................................................................................................................................ 0.15/0.35

Chromium .......................................................................................................................................................................................... 0.80/1.10

Molybdenum ...................................................................................................................................................................................... 0.18/0.25

TABLE 2.—CHECK ANALYSIS TOLERANCES

Element Limit or maximum specified (percent)

Tolerance (percent) over

the maximum limit or

under the minimum limit

Under minimum limitOver maximum limit

Carbon ...................................................................................................... Over 0.15 to 0.40 incl ............................... .03 .04

Manganese ............................................................................................... To 0.60 incl ............................................... .03 .03

Phosphorus1 ............................................................................................. All ranges .................................................. .................... .01

Sulphur ...................................................................................................... All ranges .................................................. .................... .01

Silicon ....................................................................................................... To 0.30 incl ............................................... .02 .03

Over 0.30 to 1.00 incl ............................... .05 .05

Chromium .................................................................................................. To 0.90 incl ............................................... .03 .03

Over 0.90 to 2.10 incl ............................... .05 .05

Molybdenum .............................................................................................. To 0.20 incl ............................................... .01 .01

Over 0.20 to 0.40 incl ............................... .02 .02

1 Rephosphorized steels not subject to check analysis for phosphorus.

(c) Identification of material. Material

must be identified by any suitable

method. Steel stamping of heat

identifications may not be made in any

area which will eventually become the

side wall of the cylinder. Depth of

stamping may not encroach upon the

minimum prescribed wall thickness of

the cylinder.

(d) Manufacture. Cylinders must be

manufactured using equipment and

processes adequate to ensure that each

cylinder produced conforms to the

requirements of this subpart. No fissure

or other defect is permitted that is likely

to weaken the finished container

appreciably. The general surface finish

may not exceed a roughness of 250

RMS. Individual irregularities such as

draw marks, scratches, pits, etc., should

be held to a minimum consistent with

good high stress pressure vessel

manufacturing practices. If the cylinder

is not originally free of such defects or

does not meet the finish requirements,

the surface may be machined or

otherwise treated to eliminate these
25952 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

defects. The point of closure of

cylinders closed by spinning may not be

less than two times the prescribed wall

thickness of the cylindrical shell. The

cylinder end contour must be

hemispherical or ellipsoidal with a ratio

of major-to-minor axis not exceeding

two to one and with the concave side to

pressure.

(e) Welding or brazing. Welding or

brazing for any purpose whatsoever is

prohibited, except that welding by

spinning is permitted to close the

bottom of spun cylinders. Machining or

grinding to produce proper surface

finish at point of closure is required.

(f) Wall thickness. (1) Minimum wall

thickness for any cylinder must be 0.050

inch. The minimum wall thickness must

be such that the wall stress at the

minimum specified test pressure may

not exceed 75 percent of the minimum

tensile strength of the steel as

determined from the physical tests

required in paragraph (m) of this section

and may not be over 105,000 psi.

(2) Calculations must be made by the

formula:

S=[P(1.3D2+0.4d2)]/(D2¥d2)

Where:

S=Wall stress in pounds per square

inch;

P=Minimum test pressure prescribed for

water jacket test;

D=Outside diameter in inches;

d=Inside diameter in inches.

(3) Wall thickness of hemispherical

bottoms only permitted to 90 percent of

minimum wall thickness of cylinder

sidewall but may not be less than 0.050

inch. In all other cases, thickness to be

no less than prescribed minimum wall.

(g) Heat treatment. The completed

cylinders must be uniformly and

properly heated prior to tests. Heat

treatment of the cylinders of the

authorized analysis must be as follows:

(1) All cylinders must be quenched by

oil, or other suitable medium.

(2) The steel temperature on

quenching must be that recommended

for the steel analysis, but may not

exceed 1750 °F.

(3) The steel must be tempered at a

temperature most suitable for the

particular steel analysis but not less

than 850 °F.

(4) All cylinders must be inspected by

the magnetic particle or dye penetrant

method to detect the presence of

quenching cracks. Any cylinder found

to have a quenching crack must be

rejected and may not be requalified.

(h) Openings in cylinders and

connections (valves, fuse plugs, etc.) for

those openings. Threads conforming to

the following are required on openings:

(1) Threads must be clean cut, even,

without cracks, and to gauge.

(2) Taper threads, when used, must be

of length not less than as specified for

National Gas Tapered Thread (NGT) as

required by American Standard

Compressed Gas Cylinder Valve Outlet

and Inlet Connections.

(3) Straight threads having at least 6

engaged threads are authorized. Straight

threads must have a tight fit and a

calculated shear stress of at least 10

times the test pressure of the cylinder.

Gaskets, adequate to prevent leakage,

are required.

(i) Hydrostatic test. Each cylinder

must withstand a hydrostatic test, as

follows:

(1) The test must be by water-jacket,

or other suitable method, operated so as

to obtain accurate data. Pressure gauge

must permit reading to an accuracy of

1 percent. The expansion gauge must

permit reading of total expansion to an

accuracy either of 1 percent of 0.1 cubic

centimeter.

(2) Pressure must be maintained for at

least 30 seconds and sufficiently longer

to ensure complete expansion. Any

internal pressure applied after heat

treatment and previous to the official

test may not exceed 90 percent of the

test pressure. If, due to failure of the test

apparatus, the test pressure cannot be

maintained, the test may be repeated at

a pressure increased by 10 percent or

100 pounds per square inch, which ever

is the lower.

(3) Permanent volumetric expansion

may not exceed 10 percent of total

volumetric expansion at test pressure.

(4) Each cylinder must be tested to at

least 5⁄3 times service pressure.

(j) Cycling tests. Prior to the initial

shipment of any specific cylinder

design, cyclic pressurization tests must

have been performed on at least three

representative samples without failure

as follows:

(1) Pressurization must be performed

hydrostatically between approximately

zero psig and the service pressure at a

rate not in excess of 10 cycles per

minute. Adequate recording

instrumentation must be provided if

equipment is to be left unattended for

periods of time.

(2) Tests prescribed in paragraph (j)(1)

of this section must be repeated on one

random sample out of each lot of

cylinders. The cylinder may then be

subjected to a burst test.

(3) A lot is defined as a group of

cylinders fabricated from the same heat

of steel, manufactured by the same

process and heat treated in the same

equipment under the same conditions of

time, temperature, and atmosphere, and

may not exceed a quantity of 200

cylinders.

(4) All cylinders used in cycling tests

must be destroyed.

(k) Burst test. One cylinder taken at

random out of each lot of cylinders must

be hydrostatically tested to destruction.

(l) Flattening test. A flattening test

must be performed on one cylinder

taken at random out or each lot of 200

or less, by placing the cylinder between

wedge shaped knife edges having a 60°

included angle, rounded to 1⁄2-inch

radius. The longitudinal axis of the

cylinder must be at a 90-degree angle to

knife edges during the test. For lots of

30 or less, flattening tests are authorized

to be made on a ring at least 8 inches

long cut from each cylinder and

subjected to same heat treatment as the

finished cylinder.

(m) Physical tests. A physical test

must be conducted to determine yield

strength, tensile strength, elongation,

and reduction of area of material, as

follows:

(1) Test is required on 2 specimens

cut from 1 cylinder taken at random out

of each lot of cylinders.

(2) Specimens must conform to the

following:

(i) A gauge length of at least 24 times

the thickness with a width not over six

times the thickness. The specimen,

exclusive of grip ends, may not be

flattened. Grip ends may be flattened to

within one inch of each end of the

reduced section. When size of cylinder

does not permit securing straight

specimens, the specimens may be taken

in any location or direction and may be

straightened or flattened cold by

pressure only, not by blows. When

specimens are so taken and prepared,

the inspector’s report must show in

connection with the record of physical

tests detailed information in regard to

such specimens.

(ii) Heating of a specimen for any

purpose is not authorized.

(3) The yield strength in tension must

be the stress corresponding to a

permanent strain of 0.2 percent of the

gauge length.

(i) The yield strength must be

determined by either the ‘‘offset’’

method or the ‘‘extension under load’’

method as prescribed in ASTM

Standard E8.

(ii) In using the ‘‘extension under

load’’ method, the total strain (or

‘‘extension under load’’) corresponding

to the stress at which the 0.2 percent

permanent strain occurs may be

determined with sufficient accuracy by

calculating the elastic extension of the

gauge length under appropriate load and

adding thereto 0.2 percent of the gauge

length. Elastic extension calculations

must be based on an elastic modulus of

30,000,000. In the event of controversy,
Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations 25953

the entire stress-strain diagram must be

plotted and the yield strength

determined from the 0.2 percent offset.

(iii) For the purpose of strain

measurement, the initial strain must be

set while the specimen is under a stress

of 12,000 pounds per square inch, the

strain indicator reading being set at the

calculated corresponding strain.

(iv) Cross-head speed of the testing

machine may not exceed 1⁄8 inch per

minute during yield strength

determination.

(n) Magnetic particle inspection.

Inspection must be performed on the

inside of each container before closing

and externally on each finished

container after heat treatment. Evidence

of discontinuities, which in the opinion

of a qualified inspector may appreciably

weaken or decrease the durability of the

cylinder, must be cause for rejection.

(o) Leakage test. All spun cylinders

and plugged cylinders must be tested for

leakage by dry gas or dry air pressure

after the bottom has been cleaned and

is free from all moisture, subject to the

following conditions and limitations:

(1) Pressure, approximately the same

as but not less than service pressure,

must be applied to one side of the

finished bottom over an area of at least

1⁄16 of the total area of the bottom but

not less than 3⁄4 inch in diameter,

including the closure, for at least one

minute, during which time the other

side of the bottom exposed to pressure

must be covered with water and closely

examined for indications of leakage.

Except as provided in paragraph (q) of

this section, a cylinder must be rejected

if there is leakage.

(2) A spun cylinder is one in which

an end closure in the finished cylinder

has been welded by the spinning

process.

(3) A plugged cylinder is one in

which a permanent closure in the

bottom of a finished cylinder has been

effected by a plug.

(4) As a safety precaution, if the

manufacturer elects to make this test

before the hydrostatic test, the

manufacturer should design the test

apparatus so that the pressure is applied

to the smallest area practicable, around

the point of closure, and so as to use the

smallest possible volume of air or gas.

(p) Acceptable results of tests. Results

of the flattening test, physical tests,

burst test, and cycling test must conform

to the following:

(1) Flattening required without

cracking to ten times the wall thickness

of the cylinder.

(2) Physical tests:

(i) An elongation of at least 6 percent

for a gauge length of 24 times the wall

thickness.

(ii) The tensile strength may not

exceed 165,000 p.s.i.

(3) The burst pressure must be at least 4⁄3 times the test pressure.

(4) Cycling-at least 10,000

pressurizations.

(q) Rejected cylinders. Reheat

treatment is authorized for rejected

cylinders. Subsequent thereto, cylinders

must pass all prescribed tests to be

acceptable. Repair by welding or

spinning is not authorized. For each

cylinder subjected to reheat treatment

during original manufacture, sidewall

measurements must be made to verify

that the minimum sidewall thickness

meets specification requirements after

the final heat treatment.

(r) Marking. (1) Cylinders must be

marked by low stress type steel

stamping in an area and to a depth

which will insure that the wall

thickness measured from the root of the

stamping to the interior surface is equal

to or greater than the minimum

prescribed wall thickness. Stamping

must be permanent and legible.

Stamping on side wall not authorized.

(2) The rejection elastic expansion

(REE), in cubic centimeters (cc), must be

marked on the cylinder near the date of

test. The REE for a cylinder is 1.05 times

its original elastic expansion.

(3) Name plates are authorized,

provided that they can be permanently

and securely attached to the cylinder.

Attachment by either brazing or welding

is not permitted. Attachment by

soldering is permitted provided steel

temperature does not exceed 500 °F.

(s) Inspector’s report. In addition to

the requirements of § 178.35, the

inspector’s report must indicate the

rejection elastic expansion (REE), in

cubic centimeters (cc).

§ 178.45 Specification 3T seamless steel

cylinder.

(a) Type, size, and service pressure. A

DOT 3T cylinder is a seamless steel

cylinder with a minimum water

capacity of 1,000 pounds and a

minimum service pressure of 1,800 p.s.i.

Each cylinder must have integrally

formed heads concave to pressure at

both ends. The inside head shape must

be hemispherical, ellipsoidal in which

the major axis is two times the minor

axis, or a dished shape falling within

these two limits. Permanent closures

formed by spinning are prohibited.

(b) Material, steel. Only open hearth,

basic oxygen, or electric furnace process

steel of uniform quality is authorized.

The steel analysis must conform to the

following:

ANALYSIS TOLERANCES

Element Ladle analysis

Check Analysis

Under Over

Carbon ....................................................................................................................................................... 0.35 to 0.50 ...... 0.03 0.04

Manganese ................................................................................................................................................ 0.75 to 1.05 ...... 0.04 0.04

Phosphorus (max) ..................................................................................................................................... 0.035 ................ ................ 0.01

Sulphur (max) ............................................................................................................................................ 0.04 .................. ................ 0.01

Silicon ........................................................................................................................................................ 0.15 to 0.35 ...... 0.02 0.03

Chromium .................................................................................................................................................. 0.80 to 1.15 ...... 0.05 0.05

Molybdenum .............................................................................................................................................. 0.15 to 0.25 ...... 0.02 0.02

(1) A heat of steel made under the

specifications in the table in this

paragraph (b), the ladle analysis of

which is slightly out of the specified

range, is acceptable if satisfactory in all

other aspects. However, the check

analysis tolerances shown in the table in

this paragraph (b) may not be exceeded

except as approved by the Department.

(2) Material with seams, cracks,

laminations, or other injurious defects is

not permitted.

(3) Material used must be identified

by any suitable method.

(c) Manufacture. General

manufacturing requirements are as

follows:

(1) Surface finish must be uniform

and reasonably smooth.

(2) Inside surfaces must be clean, dry,

and free of loose particles.
25954 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

(3) No defect of any kind is permitted

if it is likely to weaken a finished

cylinder.

(4) If the cylinder surface is not

originally free from the defects, the

surface may be machined or otherwise

treated to eliminate these defects

provided the minimum wall thickness is

maintained.

(5) Welding or brazing on a cylinder

is not permitted.

(d) Wall thickness. The minimum

wall thickness must be such that the

wall stress at the minimum specified

test pressure does not exceed 67 percent

of the minimum tensile strength of the

steel as determined by the physical tests

required in paragraphs (j) and (k) of this

section. A wall stress of more than

90,500 p.s.i. is not permitted. The

minimum wall thickness for any

cylinder may not be less than 0.225

inch.

(1) Calculation of the stress for

cylinders must be made by the

following formula:

S=[P(1.3D2+0.4d2)]/(D2¥d2)

Where:

S=Wall stress in pounds per square

inch;

P=Minimum test pressure, at least 5⁄3

service pressure;

D=Outside diameter in inches;

d=Inside diameter in inches.

(2) Each cylinder must meet the

following additional requirement which

assumes a cylinder horizontally

supported at its two ends and uniformly

loaded over its entire length. This load

consists of the weight per inch of length

of the straight cylindrical portion filled

with water compressed to the specified

test pressure. The wall thickness must

be increased when necessary to meet

this additional requirement:

(i) The sum of two times the

maximum tensile stress in the bottom

fibers due to bending (see paragraph

(d)(2)(ii) of this section), plus the

maximum tensile stress in the same

fibers due to hydrostatic testing (see

paragraph (d)(2)(iii) of this section) may

not exceed 80 percent of the minimum

yield strength of the steel at this

maximum stress.

(ii) The following formula must be

used to calculate the maximum tensile

stress due to bending:

S=Mc/I

Where:

S=Tensile stress in pounds per square

inch;

M=Bending moment in inch-pounds

(wl2/8);

I=Moment of inertia—0.04909 (D4¥d4)

in inches fourth;

c=Radius (D/2) of cylinder in inches;

w=Weight per inch of cylinder filled

with water;

l=Length of cylinder in inches;

D=Outside diameter in inches;

d=Inside diameter in inches.

(iii) The following formula must be

used to calculate the maximum

longitudinal tensile stress due to

hydrostatic test pressure:

S=A1P/A2

Where:

S=Tensile stress in pounds per square

inch;

A1=Internal area in cross section of

cylinder in square inches;

P=Hydrostatic test pressure in pounds

per square, inch;

A2=Area of metal in cross section of

cylinder in square inches.

(e) Heat treatment. Each completed

cylinder must be uniformly and

properly heat treated prior to testing, as

follows:

(1) Each cylinder must be heated and

held at the proper temperature for at

least one hour per inch of thickness

based on the maximum thickness of the

cylinder and then quenched in a

suitable liquid medium having a cooling

rate not in excess of 80 percent of water.

The steel temperature on quenching

must be that recommended for the steel

analysis, but it must never exceed 1750

°F.

(2) After quenching, each cylinder

must be reheated to a temperature below

the transformation range but not less

than 1050 °F., and must be held at this

temperature for at least one hour per

inch of thickness based on the

maximum thickness of the cylinder.

Each cylinder must then be cooled

under conditions recommended for the

steel.

(f) Openings. Openings in cylinders

must comply with the following:

(1) Openings are permitted on heads

only.

(2) The size of any centered opening

in a head may not exceed one half the

outside diameter of the cylinder.

(3) Openings in a head must have

ligaments between openings of at least

three times the average of their hole

diameter. No off-center opening may

exceed 2.625 inches in diameter.

(4) All openings must be circular.

(5) All openings must be threaded.

Threads must be in compliance with the

following:

(i) Each thread must be clean cut,

even, without any checks, and to gauge.

(ii) Taper threads, when used, must be

the American Standard Pipe thread

(NPT) type and must be in compliance

with the requirements of NBS Handbook

H–28, Part II, Section VII.

(iii) Taper threads conforming to

National Gas Taper thread (NGT)

standards must be in compliance with

the requirements of NBS Handbook H–

28, Part II, Sections VII and IX.

(iv) Straight threads conforming with

National Gas Straight thread (NGS)

standards are authorized. These threads

must be in compliance with the

requirements of NBS Handbook H–28,

Part II, Sections VII and IX.

(g) Hydrostatic test. Each cylinder

must be tested at an internal pressure by

the water jacket method or other

suitable method, conforming to the

following requirements:

(1) The testing apparatus must be

operated in a manner that will obtain

accurate data. Any pressure gauge used

must permit reading to an accuracy of

one percent. Any expansion gauge used

must permit reading of the total

expansion to an accuracy of one

percent.

(2) Any internal pressure applied to

the cylinder after heat treatment and

before the official test may not exceed

90 percent of the test pressure.

(3) The pressure must be maintained

sufficiently long to assure complete

expansion of the cylinder. In no case

may the pressure be held less than 30

seconds.

(4) If, due to failure of the test

apparatus, the required test pressure

cannot be maintained, the test must be

repeated at a pressure increased by 10

percent or 100 p.s.i., whichever is lower

or, the cylinder must be reheat treated.

(5) Permanent volumetric expansion

of the cylinder may not exceed 10

percent of its total volumetric expansion

at the required test pressure.

(6) Each cylinder must be tested to at

least 5⁄3 times its service pressure.

(h) Ultrasonic examination. After the

hydrostatic test, the cylindrical section

of each vessel must be examined in

accordance with ASTM Standard A–

388–67 using the angle beam technique.

The equipment used must be calibrated

to detect a notch equal to five percent

of the design minimum wall thickness.

Any discontinuity indication greater

than that produced by the five percent

notch must be cause for rejection of the

cylinder unless the discontinuity is

repaired within the requirements of this

specification.

(i) Basic requirements for tension and

Charpy impact tests. Cylinders must be

subjected to a tension and Charpy

impact as follows:

(1) When the cylinders are heat

treated in a batch furnace, two tension

specimens and three Charpy impact

specimens must be tested from one of

the cylinders or a test ring from each

batch. The lot size represented by these

tests may not exceed 200 cylinders.
Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations 25955

(2) When the cylinders are heat

treated in a continuous furnace, two

tension specimens and three Charpy

impact specimens must be tested from

one of the cylinders or a test ring from

each four hours or less of production.

However, in no case may a test lot based

on this production period exceed 200

cylinders.

(3) Each specimen for the tension and

Charpy impact tests must be taken from

the side wall of a cylinder or from a ring

which has been heat treated with the

finished cylinders of which the

specimens must be representative. The

axis of the specimens must be parallel

to the axis of the cylinder. Each cylinder

or ring specimen for test must be of the

same diameter, thickness, and metal as

the finished cylinders they represent. A

test ring must be at least 24 inches long

with ends covered during the heat

treatment process so as to simulate the

heat treatment process of the finished

cylinders it represents.

(4) A test cylinder or test ring need

represent only one of the heats in a

furnace batch provided the other heats

in the batch have previously been tested

and have passed the tests and that such

tests do not represent more than 200

cylinders from any one heat.

(5) The test results must conform to

the requirements specified in

paragraphs (j) and (k) of this section.

(6) When the test results do not

conform to the requirements specified,

the cylinders represented by the tests

may be reheat treated and the tests

repeated. Paragraph (i)(5) of this section

applies to any retesting.

(j) Basic conditions for acceptable

physical testing. The following criteria

must be followed to obtain acceptable

physical test results:

(1) Each tension specimen must have

a gauge length of two inches with a

width not exceeding one and one-half

inches. Except for the grip ends, the

specimen may not be flattened. The grip

ends may be flattened to within one

inch of each end of the reduced section.

(2) A specimen may not be heated

after heat treatment specified in

paragraph (d) of this section.

(3) The yield strength in tension must

be the stress corresponding to a

permanent strain of 0.2 percent of the

gage length.

(i) This yield strength must be

determined by the ‘‘offset’’ method or

the ‘‘extension under load’’ method

described in ASTM Standard E8.

(ii) For the ‘‘extension under load’’

method, the total strain (or extension

under load) corresponding to the stress

at which the 0.2 percent permanent

strain occurs may be determined with

sufficient accuracy by calculating the

elastic extension of the gage length

under appropriate load and adding

thereto 0.2 percent of the gage length.

Elastic extension calculations must be

based on an elastic modulus of

30,000,000. However, when the degree

of accuracy of this method is

questionable the entire stress-strain

diagram must be plotted and the yield

strength determined from the 0.2

percent offset.

(iii) For the purpose of strain

measurement, the initial strain must be

set with the specimen under a stress of

12,000 p.s.i. and the strain indicator

reading set at the calculated

corresponding strain.

(iv) The cross-head speed of the

testing machine may not exceed 1⁄8 inch

per minute during the determination of

yield strength.

(4) Each impact specimen must be

Charpy V-notch type size 10 mm x 10

mm taken in accordance with paragraph

11 of ASTM Standard A–333–67. When

a reduced size specimen is used, it must

be the largest size obtainable.

(k) Acceptable physical test results.

Results of physical tests must conform

to the following:

(1) The tensile strength may not

exceed 155,000 p.s.i.

(2) The elongation must be at least 16

percent for a two-inch gage length.

(3) The Charpy V-notch impact

properties for the three impact

specimens which must be tested at 0 °F

may not be less than the values shown

as follows:

Size of specimen (mm) Average value for acceptance (3 specimens)

Minimum value

(1 specimen

only of the 3)

10.0x10.0 ................................................................................... 25.0 ft. lbs. ................................................................................ 20.0 ft. lbs.

10.0x7.5 ..................................................................................... 21.0 ft. lbs. ................................................................................ 17.0 ft. lbs.

10.0x5.0 ..................................................................................... 17.0 ft. lbs. ................................................................................ 14.0 ft. lbs.

(4) After the final heat treatment, each

vessel must be hardness tested on the

cylindrical section. The tensile strength

equivalent of the hardness number

obtained may not be more than 165,000

p.s.i. (Rc 36). When the result of a

hardness test exceeds the maximum

permitted, two or more retests may be

made; however, the hardness number

obtained in each retest may not exceed

the maximum permitted.

(l) Rejected cylinders. Reheat

treatment is authorized for rejected

cylinders. However, each reheat treated

cylinder must subsequently pass all the

prescribed tests. Repair by welding is

not authorized.

(m) Markings. Marking must be done

by stamping into the metal of the

cylinder. All markings must be legible

and located on a shoulder.

(n) Inspector’s report. In addition to

the requirements of § 178.35, the

inspector’s report for the physical test

report, must indicate the average value

for three specimens and the minimum

value for one specimen for each lot

number.

§ 178.46 Specification 3AL seamless

aluminum cylinders.

(a) Size and service pressure. A DOT

3AL cylinder is a seamless aluminum

cylinder with a maximum water

capacity of 1000 pounds and minimum

service pressure of 150 psig.

(b) Authorized material and

identification of material. The material

of construction must meet the following

conditions:

(1) Starting stock must be cast stock

or traceable to cast stock.

(2) Material with seams, cracks,

laminations, or other defects likely to

weaken the finished cylinder may not

be used.

(3) Material must be identified by a

suitable method that will identify the

alloy, the aluminum producer’s cast

number, the solution heat treat batch

number and the lot number.

(4) The material must be of uniform

quality. Only the following heat

treatable aluminum alloys in Table 1

and 2 are permitted as follows:
25956 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

TABLE 1.—CHEMICAL COMPOSITION LIMITS

[Chemical composition (in weight percent)]

Aluminum Assoc. alloy designation

No. Si Fe Cu Mn Mg Cr Zn Ti Pb Bi

Other 1

A1

Each Total

6351 .................................................... 0.7–1.3 0.50 0.10 0.40–0.80 0.40–0.80 ................ 0.20 0.20 0.01 0.01 0.05 0.15 Remainder.

6061 .................................................... 0.40–0.80 0.70 0.15–0.40 0.15 0.80–1.20 0.04–0.35 0.25 0.15 0.01 0.01 0.05 0.15 Remainder.

1Analysis is regularly made only for the elements for which specific limits are shown, except for unalloyed aluminum. If, however, the presence of other elements is

suspected to be, or in the course of routine analysis is indicated to be in excess of specified limits, further analysis is made to determine that these other elements

are not in excess of the amounts specified. (Aluminum Association Standards and Data.)

TABLE 2.—MECHANICAL PROPERTY LIMITS

Alloy and temper

Tensile strength—PSI Elongation—

percent minimum for 2′′

or 4D 1 size

specimen

Ultimate—

minimum

Yield—

minimum

6351–T6 ............................................................................................................................................. 42,000 37,000 214

6061–T6 ............................................................................................................................................. 38,000 35,000 214

1 ‘‘D’’ represents specimen diameters. When the cylinder wall is greater than 3⁄16 inch thick, a retest without reheat treatment using the 4D size

specimen is authorized if the test using the 2 inch size specimen fails to meet elongation requirements. 2When cylinder wall is not over 3⁄16-inch thick, 10 percent elongation is authorized when using a 24t x 6t size test specimen.

(5) All starting stock must be 100

percent ultrasonically inspected, along

the length at right angles to the central

axis from two positions at 90° to one

another. The equipment and continuous

scanning procedure must be capable of

detecting and rejecting internal defects

such as cracks which have an ultrasonic

response greater than that of a

calibration block with a 5⁄64-inch

diameter flat bottomed hole.

(6) Cast stock must have uniform

equiaxed grain structure not to exceed

500 microns maximum.

(7) Any starting stock not complying

with the provisions of paragraphs (b)(1)

through (b)(6) of this section must be

rejected.

(c) Manufacture. Cylinders must be

manufactured in accordance with the

following requirements:

(1) Cylinder shells must be

manufactured by the backward

extrusion method and have a

cleanliness level adequate to ensure

proper inspection. No fissure or other

defect is acceptable that is likely to

weaken the finished cylinder below the

design strength requirements. A

reasonably smooth and uniform surface

finish is required. If not originally free

from such defects, the surface may be

machined or otherwise conditioned to

eliminate these defects.

(2) Thickness of the cylinder base may

not be less than the prescribed

minimum wall thickness of the

cylindrical shell. The cylinder base

must have a basic torispherical,

hemispherical, or ellipsoidal interior

base configuration where the dish

radius is no greater than 1.2 times the

inside diameter of the shell. The

knuckle radius may not be less than 12

percent of the inside diameter of the

shell. The interior base contour may

deviate from the true torispherical,

hemispherical or ellipsoidal

configuration provided that—

(i) Any areas of deviation are

accompanied by an increase in base

thickness;

(ii) All radii of merging surfaces are

equal to or greater than the knuckle

radius;

(iii) Each design has been qualified by

successfully passing the cycling tests in

this paragraph (c); and

(iv) Detailed specifications of the base

design are available to the inspector.

(3) For free standing cylinders, the

base thickness must be at least two

times the minimum wall thickness

along the line of contact between the

cylinder base and the floor when the

cylinders are in the vertical position.

(4) Welding or brazing is prohibited.

(5) Each new design and any

significant change to any acceptable

design must be qualified for production

by testing prototype samples as follows:

(i) Three samples must be subjected to

100,000 pressure reversal cycles

between zero and service pressure or

10,000 pressure reversal cycles between

zero and test pressure, at a rate not in

excess of 10 cycles per minute without

failure.

(ii) Three samples must be

pressurized to destruction and failure

may not occur at less than 2.5 times the

marked cylinder service pressure. Each

cylinder must remain in one piece.

Failure must initiate in the cylinder

sidewall in a longitudinal direction.

Rate of pressurization may not exceed

200 psi per second.

(6) In this specification ‘‘significant

change’’ means a 10 percent or greater

change in cylinder wall thickness,

service pressure, or diameter; a 30

percent or greater change in water

capacity or base thickness; any change

in material; over 100 percent increase in

size of openings; or any change in the

number of openings.

(d) Wall thickness. The minimum

wall thickness must be such that the

wall stress at the minimum specified

test pressure will not exceed 80 percent

of the minimum yield strength nor

exceed 67 percent of the minimum

ultimate tensile strength as verified by

physical tests in paragraph (i) of this

section. The minimum wall thickness

for any cylinder with an outside

diameter greater than 5 inches must be

0.125 inch. Calculations must be made

by the following formula:

S=[P(1.3D2+0.4d2)]/(D2¥d2)

Where:

S=Wall stress in pounds per square

inch;

P=Prescribed minimum test pressure in

pounds per square inch (see

paragraph (g) of this section);

D=Outside diameter in inches; and

d=Inside diameter in inches.

(e) Openings. Openings must comply

with the following requirements:

(1) Openings are permitted in heads

only.

(2) The size of any centered opening

in a head may not exceed one-half the

outside diameter of the cylinder.

(3) Other openings are permitted in

the head of a cylinder if:

(i) Each opening does not exceed

2.625 inches in diameter, or one-half the

outside diameter of the cylinder;

whichever is less;
Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations 25957

(ii) Each opening is separated from

each other by a ligament; and

(iii) Each ligament which separates

two openings must be at least three

times the average of the diameters of the

two openings.

(4) All openings must be circular.

(5) All openings must be threaded.

Threads must comply with the

following:

(i) Each thread must be clean cut,

even, without checks, and to gauge.

(ii) Taper threads, when used, must

conform to one of the following:

(A) American Standard Pipe Thread

(NPT) type, conforming to the

requirements of Federal Standard H–28,

Section 7;

(B) National Gas Taper Thread (NGT)

type, conforming to the requirements of

Federal Standard H–28, Sections 7 and

9; or

(C) Other taper threads conforming to

other standards may be used provided

the length is not less than that specified

for NPT threads.

(iii) Straight threads, when used, must

conform to one of the following:

(A) National Gas Straight Thread

(NGS) type, conforming to the

requirements of Federal Standard H–28,

Sections 7 and 9;

(B) Unified Thread (UN) type,

conforming to the requirements of

Federal Standard H–28, Section 2;

(C) Controlled Radius Root Thread

(UN) type, conforming to the

requirements of Federal Standard H–28,

Section 4; or

(D) Other straight threads conforming

to other recognized standards may be

used provided that the requirements in

paragraph (e)(5)(iv) of this section are

met.

(iv) All straight threads must have at

least 6 engaged threads, a tight fit, and

a factor of safety in shear of at least 10

at the test pressure of the cylinder.

Shear stress must be calculated by using

the appropriate thread shear area in

accordance with Federal Standard H–

28, Appendix A5, Section 3.

(f) Heat treatment. Prior to any test,

all cylinders must be subjected to a

solution heat treatment and aging

treatment appropriate for the aluminum

alloy used.

(g) Hydrostatic test. Each cylinder

must be subjected to an internal test

pressure using the water jacket

equipment and method or other suitable

equipment and method and comply

with the following requirements:

(1) The testing apparatus must be

operated in a manner so as to obtain

accurate data. The pressure gauge used

must permit reading to an accuracy of

one percent. The expansion gauge must

permit reading the total expansion to an

accuracy of either one percent or 0.1

cubic centimeter.

(2) The test pressure must be

maintained for a sufficient period of

time to assure complete expansion of

the cylinder. In no case may the

pressure be held less than 30 seconds.

If, due to failure of the test apparatus,

the required test pressure cannot be

maintained, the test may be repeated at

a pressure increased by 10 percent or

100 psi, whichever is lower. If the test

apparatus again fails to maintain the test

pressure, the cylinder being tested must

be rejected. Any internal pressure

applied to the cylinder before any

official test may not exceed 90 percent

of the test pressure.

(3) The minimum test pressure is the

greatest of the following:

(i) 450 psi regardless of service

pressure;

(ii) Two times the service pressure for

cylinders having service pressure less

than 500 psi; or

(iii) Five-thirds times the service

pressure for cylinders having a service

pressure of at least 500 psi.

(4) Permanent volumetric expansion

may not exceed 10 percent of total

volumetric expansion at test pressure.

(h) Flattening test. One cylinder taken

at random out of each lot must be

subjected to a flattening test as follows:

(1) The test must be between knife

edges, wedge shaped, having a 60°

included angle, and rounded in

accordance with the following table.

The longitudinal axis of the cylinder

must be at an angle 90° to the knife

edges during the test. The flattening test

table is as follows:

TABLE 3.—FLATTENING TEST TABLE

Cylinder wall thickness in inches

Radius

in

inches

Under .150 ...................................... .500

.150 to .249 ..................................... .875

.250 to .349 ..................................... 1.500

.350 to .449 ..................................... 2.125

.450 to .549 ..................................... 2.750

.550 to .649 ..................................... 3.500

.650 to .749 ..................................... 4.125

(2) An alternate bend test in

accordance with ASTM E 290 using a

mandrel diameter not more than 6 times

the wall thickness is authorized to

qualify lots that fail the flattening test of

this section without reheat treatment. If

used, this test must be performed on

two samples from one cylinder taken at

random out of each lot of 200 cylinders

or less.

(3) Each test cylinder must withstand

flattening to nine times the wall

thickness without cracking. When the

alternate bend test is used, the test

specimens must remain uncracked

when bent inward around a mandrel in

the direction of curvature of the

cylinder wall until the interior edges are

at a distance apart not greater than the

diameter of the mandrel.

(i) Mechanical properties test. Two

test specimens cut from one cylinder

representing each lot of 200 cylinders or

less must be subjected to the mechanical

properties test, as follows:

(1) The results of the test must

conform to at least the minimum

acceptable mechanical property limits

for aluminum alloys as specified in

paragraph (b) of this section.

(2) Specimens must be 4D bar or

gauge length 2 inches with width not

over 11⁄2 inch taken in the direction of

extrusion approximately 180° from each

other; provided that gauge length at

least 24 times thickness with width not

over 6 times thickness is authorized,

when cylinder wall is not over 3⁄16 inch

thick. The specimen, exclusive of grip

ends, may not be flattened. Grip ends

may be flattened to within one inch of

each end of the reduced section. When

the size of the cylinder does not permit

securing straight specimens, the

specimens may be taken in any location

or direction and may be straightened or

flattened cold by pressure only, not by

blows. When such specimens are used,

the inspector’s report must show that

the specimens were so taken and

prepared. Heating of specimens for any

purpose is forbidden.

(3) The yield strength in tension must

be the stress corresponding to a

permanent strain of 0.2 percent of the

gauge length.

(i) The yield strength must be

determined by either the ‘‘offset’’

method or the ‘‘extension under load’’

method as prescribed in ASTM

Standard B–557.

(ii) In using the ‘‘extension under

load’’ method, the total strain (or

‘‘extension under load’’) corresponding

to the stress at which the 0.2 percent

permanent strain occurs may be

determined with sufficient accuracy by

calculating the elastic extension of the

gauge length under appropriate load and

adding thereto 0.2 percent of the gauge

length. Elastic extension calculations

must be based on an elastic modulus of

10,000,000 psi. In the event of

controversy, the entire stress-strain

diagram must be plotted and the yield

strength determined from the 0.2

percent offset.

(iii) For the purpose of strain

measurement, the initial strain must be

set while the specimen is under a stress

of 6,000 psi, the strain indicator reading
25958 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

being set at the calculated

corresponding strain.

(iv) Cross-head speed of the testing

machine may not exceed 1⁄8 inch per

minute during yield strength

determination.

(j) Rejected cylinder. Reheat treatment

of rejected cylinders is authorized one

time. Subsequent thereto, cylinders

must pass all prescribed tests to be

acceptable.

(k) Duties of inspector. In addition to

the requirements of § 178.35, the

inspector shall:

(1) Verify compliance with the

provisions of paragraph (b) of this

section by:

(i) Performing or witnessing the

performance of the chemical analyses

on each melt or cast lot or other unit of

starting material; or

(ii) Obtaining a certified chemical

analysis from the material or cylinder

manufacturer for each melt, or cast of

material; or

(iii) Obtaining a certified check

analysis on one cylinder out of each lot

of 200 cylinders or less, if a certificate

containing data to indicate compliance

with the material specification is

obtained.

(2) The inspector shall verify

ultrasonic inspection of all material by

inspection or by obtaining the material

producer’s certificate of ultrasonic

inspection. Ultrasonic inspection must

be performed or verified as having been

performed in accordance with

paragraph (c) of this section.

(3) The inspector must also determine

that each cylinder complies with this

specification by:

(i) Selecting the samples for check

analyses performed by other than the

material producer;

(ii) Verifying that the prescribed

minimum thickness was met by

measuring or witnessing the

measurement of the wall thickness; and

(iii) Verifying that the identification of

material is proper.

(4) Prior to initial production of any

design or design change, verify that the

design qualification tests prescribed in

paragraph (c)(6) of this section have

been performed with acceptable results.

(l) Definitions. (1) In this

specification, a ‘‘lot’’ means a group of

cylinders successively produced having

the same:

(i) Size and configuration;

(ii) Specified material of construction;

(iii) Process of manufacture and heat

treatment;

(iv) Equipment of manufacture and

heat treatment; and

(v) Conditions of time, temperature

and atmosphere during heat treatment.

(2) In no case may the lot size exceed

200 cylinders, but any cylinder

processed for use in the required

destructive physical testing need not be

counted as being one of the 200.

(m) Inspector’s report. In addition to

the information required by § 178.35,

the record of chemical analyses must

also include the alloy designation, and

applicable information on iron,

titanium, zinc, magnesium and any

other applicable element used in the

construction of the cylinder.

§ 178.47 Specification 4DS welded

stainless steel cylinders for aircraft use.

(a) Type, size, and service pressure. A

DOT 4DS cylinder is either a welded

stainless steel sphere (two seamless

hemispheres) or circumferreentially

welded cylinder both with a water

capacity of not over 100 pounds and a

service pressure of at least 500 but not

over 900 pounds per square inch.

(b) Steel. Types 304, 321 and 347

stainless steel are authorized with

proper welding procedure. A heat of

steel made under the specifications in

Table 1 in this paragraph (b), check

chemical analysis of which is slightly

out of the specified range, is acceptable,

if satisfactory in all other respects,

provided the tolerances shown in Table

2 in this paragraph (b) are not exceeded,

except as approved by Associate

Administrator. The following chemical

analyses are authorized:

TABLE 1.—AUTHORIZED MATERIALS

Stainless steels

304 (percent) 321 (percent) 347 (percent)

Carbon (max) ...................................................................... 0.08 0.08 0.08

Manganese (max) ............................................................... 2.00 2.00 2.00

Phosphorus (max) ............................................................... .030 .030 .030

Sulphur (max) ...................................................................... .030 .030 .030

Silicon (max) ....................................................................... .75 .75 .75

Nickel ................................................................................... 8.0/11.0 9.0/13.0 9.0/13.0

Chromium ............................................................................ 18.0/20.0 17.0/20.0 17.0/20.0

Molybdenum

Titanium ............................................................................... (1)

Columbium .......................................................................... (2)

1Titanium may not be more than 5C and not more than 0.60%.

2 Columbium may not be less than 10C and not more than 1.0%.

TABLE 2.—CHECK ANALYSIS TOLERANCES

Element Limit or maximum specified (percent)

Tolerance (percent) over

the maximum limit or

under the minimum limit

Under minimum limitOver maximum limit

Carbon ...................................................................................................... To 0.15 incl ............................................... 0.01 0.01

Manganese ............................................................................................... Over 1.15 to 2.50 incl ............................... 0.05 0.05

Phosphorus1 ............................................................................................. All ranges .................................................. .................... .01

Sulphur ...................................................................................................... All ranges .................................................. .................... .01

Silicon ....................................................................................................... Over 0.30 to 1.00 incl ............................... .05 .05

Nickel ........................................................................................................ Over 5.30 to 10.00 incl ............................. .10 .10

Over 10.00 to 14.00 incl ........................... .15 .15
Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations 25959

TABLE 2.—CHECK ANALYSIS TOLERANCES—Continued

Element Limit or maximum specified (percent)

Tolerance (percent) over

the maximum limit or

under the minimum limit

Under minimum limitOver maximum limit

Chromium .................................................................................................. Over 15.00 to 20.00 incl ........................... .20 .20

Titanium .................................................................................................... All ranges .................................................. .05 .05

Columbium ................................................................................................ All ranges .................................................. .05 .05

1Rephosphorized steels not subject to check analysis for phosphorus.

(c) Identification of material.

Materials must be identified by any

suitable method.

(d) Manufacture. Cylinders must be

manufactured using equipment and

processes adequate to ensure that each

cylinder produced conforms to the

requirements of this subpart. No defect

is permitted that is likely to weaken the

finished cylinder appreciably, a

reasonably smooth and uniform surface

finish is required. No abrupt change in

wall thickness is permitted. Welding

procedures and operators must be

qualified in accordance with CGA

Pamphlet C–3. All seams of the sphere

or cylinder must be fusion welded.

Seams must be of the butt type and

means must be provided for

accomplishing complete penetration of

the joint.

(e) Attachments. Attachments to the

container are authorized by fusion

welding provided that such attachments

are made of weldable stainless steel in

accordance with paragraph (b) of this

section.

(f) Wall thickness. The minimum wall

thickness must be such that the wall

stress at the minimum specified test

pressure may not be over 60,000 psi. A

minimum wall thickness of 0.040 inch

is required for any diameter container.

Calculations must be made by the

following formulas:

(1) Calculation for sphere must be

made by the formula:

S=PD/4tE

Where:

S=Wall stress in pounds per square

inch;

P=Test pressure prescribed for water

jacket test, i.e., at least two times

service pressure, in pounds per

square inch;

D=Outside diameter in inches;

t=Minimum wall thickness in inches;

E=0.85 (provides 85 percent weld

efficiency factor which must be

applied in the girth weld area and

heat zones which zone must extend

a distance of 6 times wall thickness

from center of weld); E=1.0 (for all

other areas).

(2) Calculation for a cylinder must be

made by the formula:

S=[P(1.3D2+0.4d2)]/(D2¥d2)

Where:

S=Wall stress in pounds per square

inch;

P=Test pressure prescribed for water

jacket test, i.e., at least two times

service pressure, in pounds per

square inch;

D=Outside diameter in inches;

d=Inside diameter in inches.

(g) Heat treatment. The seamless

hemispheres and cylinders may be

stress relieved or annealed for forming.

Welded container must be stress

relieved at a temperature of 775° F +/¥

25° after process treatment and before

hydrostatic test.

(h) Openings in container. Openings

must comply with the following:

(1) Each opening in the container

must be provided with a fitting, boss or

pad of weldable stainless steel securely

attached to the container by fusion

welding.

(2) Attachments to a fitting, boss, or

pad must be adequate to prevent

leakage. Threads must comply with the

following:

(i) Threads must be clean cut, even,

without checks, and tapped to gauge.

(ii) Taper threads to be of length not

less than as specified for American

Standard taper pipe threads.

(iii) Straight threads having at least 4

engaged threads, to have tight fit and

calculated shear strength at least 10

times the test pressure of the container;

gaskets required, adequate to prevent

leakage.

(i) Process treatment. Each container

must be hydraulically pressurized in a

water jacket to at least 100 percent, but

not more than 110 percent, of the test

pressure and maintained at this pressure

for a minimum of 3 minutes. Total and

permanent expansion must be recorded

and included in the inspector’s report.

(j) Hydrostatic test. Each cylinder

must successfully withstand a

hydrostatic test as follows:

(1) The test must be by water-jacket,

operated so as to obtain accurate data.

The pressure gauge must permit reading

to an accuracy of 1 percent. The

expansion gauge must permit reading of

total expansion to an accuracy either of

1 percent or 0.1 cubic centimeter.

(2) Pressure must be maintained for at

least 30 seconds and sufficiently longer

to ensure complete expansion. If, due to

failure of the test apparatus, the test

pressure cannot be maintained, the test

may be repeated at a pressure increased

by 10 percent or 100 pounds per square

inch, whichever is the lower.

(3) Permanent volumetric expansion

may not exceed 10 percent of total

volumetric expansion at test pressure.

(4) Each container must be tested to

at least 2 times service pressure.

(5) Container must then be inspected.

Any wall thickness lower than that

required by paragraph (f) of this section

must be cause for rejection. Bulges and

cracks must be cause for rejection.

Welded joint defects exceeding

requirements of paragraph (k) of this

section must be cause for rejection.

(k) Radiographic inspection.

Radiographic inspection is required on

all welded joints which are subjected to

internal pressure, except that at the

discretion of the disinterested inspector,

openings less than 25 percent of the

container diameter need not be

subjected to radiographic inspection.

Evidence of any defects likely to

seriously weaken the container is cause

for rejection. Radiographic inspection

must be performed subsequent to the

hydrostatic test.

(l) Burst test. One container taken at

random out of 200 or less must be

hydrostatically tested to destruction.

Rupture pressure must be included as

part of the inspector’s report.

(m) Flattening test. A flattening test

must be performed as follows:

(1) For spheres the test must be at the

weld between parallel steel plates on a

press with welded seam at right angles

to the plates. Test one sphere taken at

random out of each lot of 200 or less

after the hydrostatic test. Any projecting

appurtenances may be cut off (by

mechanical means only) prior to

crushing.
25960 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

(2) For cylinders the test must be

between knife edges, wedge shaped, 60°

angle, rounded to 1⁄2-inch radius. Test

one cylinder taken at random out of

each lot of 200 or less, after the

hydrostatic test.

(n) Acceptable results for flattening

and burst tests. Acceptable results for

flattening and burst tests are as follows:

(1) Flattening required to 50 percent

of the original outside diameter without

cracking.

(2) Burst pressure must be at least 3

times the service pressure.

(o) Rejected containers. Repair of

welded seams by welding prior to

process treatment is authorized.

Subsequent thereto, containers must be

heat treated and pass all prescribed

tests.

(p) Duties of inspector. In addition to

the requirements of § 178.35, the

inspector must verify that all tests are

conducted at temperatures between 60

°F and 90 °F.

(q) Marking. Markings must be

stamped plainly and permanently on a

permanent attachment or on a metal

nameplate permanently secured to the

container by means other than soft

solder.

§ 178.50 Specification 4B welded or brazed

steel cylinders.

(a) Type, size, and service pressure. A

DOT 4B is a welded or brazed steel

cylinder with longitudinal seams that

are forged lap-welded or brazed and

with water capacity (nominal) not over

1,000 pounds and a service pressure of

at least 150 but not over 500 pounds per

square inch. Cylinders closed in by

spinning process are not authorized.

(b) Steel. Open-hearth, electric or

basic oxygen process steel of uniform

quality must be used. Content percent

may not exceed the following: Carbon,

0.25; phosphorus, 0.045; sulphur, 0.050.

(c) Identification of material. Material

must be identified by any suitable

method except that plates and billets for

hotdrawn cylinders must be marked

with the heat number.

(d) Manufacture. Cylinders must be

manufactured using equipment and

processes adequate to ensure that each

cylinder produced conforms to the

requirements of this subpart. No defect

is permitted that is likely to weaken the

finished cylinder appreciably. A

reasonably smooth and uniform surface

finish is required. Exposed bottom

welds on cylinders over 18 inch long

must be protected by footrings. Welding

procedures and operators must be

qualified in accordance with CGA

Pamphlet C–3. Seams must be made as

follows:

(1) Welded or brazed circumferential

seams. Heads attached by brazing must

have a driving fit with the shell, unless

the shell is crimped, swedged, or curled

over the skirt or flange of the head, and

be thoroughly brazed until complete

penetration by the brazing material of

the brazed joint is secured. Depth of

brazing from end of shell must be at

least four times the thickness of shell

metal.

(2) Longitudinal seams in shells.

Longitudinal seams must be forged lap

welded, by copper brazing, by copper

alloy brazing, or by silver alloy brazing.

Copper alloy composition must be:

Copper, 95 percent minimum; Silicon,

1.5 percent to 3.85 percent; Manganese,

0.25 percent to 1.10 percent. The

melting point of the silver alloy brazing

material must be in excess of 1000° F.

When brazed, the plate edge must be

lapped at least eight times the thickness

of plate, laps being held in position,

substantially metal to metal, by riveting

or electric spot-welding; brazing must

be done by using a suitable flux and by

placing brazing material on one side of

seam and applying heat until this

material shows uniformly along the

seam of the other side.

(e) Welding or brazing. Only the

attachment of neckrings, footrings,

handles, bosses, pads, and valve

protection rings to the tops and bottoms

of cylinders by welding or brazing is

authorized. Such attachments and the

portion of the container to which they

are attached must be made of weldable

steel, the carbon content of which may

not exceed 0.25 percent except in the

case of 4130X steel which may be used

with proper welding procedure.

(f) Wall thickness. The wall thickness

of the cylinder must comply with the

following requirements:

(1) For cylinders with outside

diameters over 6 inches the minimum

wall thickness must be 0.090 inch. In

any case, the minimum wall thickness

must be such that calculated wall stress

at minimum test pressure (paragraph

(i)(4) of this section) may not exceed the

following values:

(i) 24,000 pounds per square inch for

cylinders without longitudinal seam.

(ii) 22,800 pounds per square inch for

cylinders having copper brazed or silver

alloy brazed longitudinal seam.

(iii) 18,000 pounds per square inch for

cylinders having forged lapped welded

longitudinal seam.

(2) Calculation must be made by the

formula:

S=[P(1.3D2+0.4d2)]/(D2¥d2)

Where:

S=wall stress in pounds per square inch;

P=minimum test pressure prescribed for

water jacket test or 450 pounds per

square inch whichever is the

greater;

D=outside diameter in inches;

d=inside diameter in inches.

(g) Heat treatment. Cylinder body and

heads, formed by drawing or pressing,

must be uniformly and properly heat

treated prior to tests.

(h) Opening in cylinders. Openings in

cylinders must conform to the

following:

(1) Each opening in cylinders, except

those for safety devices, must be

provided with a fitting, boss, or pad,

securely attached to cylinder by brazing

or by welding or by threads. Fitting,

boss, or pad must be of steel suitable for

the method of attachment employed,

and which need not be identified or

verified as to analysis except that if

attachment is by welding, carbon

content may not exceed 0.25 percent. If

threads are used, they must comply

with the following:

(i) Threads must be clean cut, even

without checks, and tapped to gauge.

(ii) Taper threads to be of length not

less than as specified for American

Standard taper pipe threads.

(iii) Straight threads, having at least 4

engaged threads, to have tight fit and

calculated shear strength at least 10

times the test pressure of the cylinder;

gaskets required, adequate to prevent

leakage.

(iv) A brass fitting may be brazed to

the steel boss or flange on cylinders

used as component parts of hand fire

extinguishers.

(2) The closure of a fitting, boss, or

pad must be adequate to prevent

leakage.

(i) Hydrostatic test. Each cylinder

must withstand a hydrostatic test as

follows:

(1) The test must be by water-jacket,

or other suitable method, operated so as

to obtain accurate data. The pressure

gauge must permit reading to an

accuracy of 1 percent. The expansion

gauge must permit reading of total

expansion to an accuracy either of 1

percent or 0.1 cubic centimeter.

(2) Pressure must be maintained for at

least 30 seconds and sufficiently longer

to ensure complete expansion. Any

internal pressure applied after heattreatment and previous to the official

test may not exceed 90 percent of the

test pressure. If, due to failure of the test

apparatus, the test pressure cannot be

maintained, the test may be repeated at

a pressure increased by 10 percent or

100 pounds per square inch, whichever

is the lower.

(3) Permanent volumetric expansion

may not exceed 10 percent of total

volumetric expansion at test pressure.
Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations 25961

(4) Cylinders must be tested as

follows:

(i) At least one cylinder selected at

random out of each lot of 200 or less

must be tested as outlined in paragraphs

(i)(1), (i)(2), and (i)(3) of this section to

at least two times service pressure.

(ii) All cylinders not tested as

outlined in paragraph (i)(4)(i) of this

section must be examined under

pressure of at least two times service

pressure and show no defect.

(j) Flattening test. After the

hydrostatic test, a flattening test must be

performed on one cylinder taken at

random out or each lot of 200 or less,

by placing the cylinder between wedge

shaped knife edges having a 60°

included angle, rounded to 1⁄2-inch

radius. The longitudinal axis of the

cylinder must be at a 90-degree angle to

knife edges during the test. For lots of

30 or less, flattening tests are authorized

to be made on a ring at least 8 inches

long cut from each cylinder and

subjected to same heat treatment as the

finished cylinder.

(k) Physical test. A physical test must

be conducted to determine yield

strength, tensile strength, elongation,

and reduction of area of material as

follows:

(1) The test is required on 2

specimens cut from 1 cylinder, or part

thereof heat-treated as required, taken at

random out of each lot of 200 or less.

For lots of 30 or less, physical tests are

authorized to be made on a ring at least

8 inches long cut from each cylinder

and subjected to same heat treatment as

the finished cylinder.

(2) Specimens must conform to the

following:

(i) A gauge length of 8 inches with a

width of not over 11⁄2 inches, a gauge

length of 2 inches with a width of not

over 11⁄2 inches, or a gauge length at

least 24 times the thickness with a

width not over 6 times the thickness is

authorized when a cylinder wall is not

over 3⁄16 inch thick.

(ii) The specimen, exclusive of grip

ends, may not be flattened. Grip ends

may be flattened to within one inch of

each end of the reduced section.

(iii) When size of cylinder does not

permit securing straight specimens, the

specimens may be taken in any location

or direction and may be straightened or

flattened cold, by pressure only, not by

blows. When specimens are so taken

and prepared, the inspector’s report

must show in connection with record of

physical tests detailed information in

regard to such specimens.

(iv) Heating of a specimen for any

purpose is not authorized.

(3) The yield strength in tension must

be the stress corresponding to a

permanent strain of 0.2 percent of the

gauge length. The following conditions

apply:

(i) The yield strength must be

determined by either the ‘‘offset’’

method or the ‘‘extension under load’’

method as prescribed in ASTM

Standard E8.

(ii) In using the ‘‘extension under

load’’ method, the total strain (or

‘‘extension under load’’) corresponding

to the stress at which the 0.2 percent

permanent strain occurs may be

determined with sufficient accuracy by

calculating the elastic extension of the

gauge length under appropriate load and

adding thereto 0.2 percent of the gauge

length. Elastic extension calculations

must be based on an elastic modulus of

30,000,000. In the event of controversy,

the entire stress-strain diagram must be

plotted and the yield strength

determined from the 0.2 percent offset.

(iii) For the purpose of strain

measurement, the initial strain must be

set while the specimen is under a stress

of 12,000 pounds per square inch, and

strain indicator reading must be set at

the calculated corresponding strain.

(iv) Cross-head speed of the testing

machine may not exceed 1⁄8 inch per

minute during yield strength

determination.

(l) Acceptable results for physical and

flattening tests. Either of the following

is an acceptable result:

(1) An elongation of at least 40

percent for a 2-inch gauge length or at

least 20 percent in other cases and yield

strength not over 73 percent of tensile

strength. In this instance, a flattening

test is not required.

(2) When cylinders are constructed of

lap welded pipe, flattening test is

required, without cracking, to 6 times

the wall thickness. In such case, the

rings (crop ends) cut from each end of

pipe, must be tested with the weld 45°

or less from the point of greatest stress.

If a ring fails, another from the same end

of pipe may be tested.

(m) Rejected cylinders. Reheat

treatment is authorized for rejected

cylinder. Subsequent thereto, cylinders

must pass all prescribed tests to be

acceptable. Repair of brazed seams by

brazing and welded seams by welding is

authorized.

(n) Markings. Markings must be

stamped plainly and permanently in

any of the following locations on the

cylinder:

(1) On shoulders and top heads when

they are not less than 0.087-inch thick.

(2) On side wall adjacent to top head

for side walls which are not less than

0.090 inch thick.

(3) On a cylindrical portion of the

shell which extends beyond the

recessed bottom of the cylinder,

constituting an integral and nonpressure part of the cylinder.

(4) On a metal plate attached to the

top of the cylinder or permanent part

thereof; sufficient space must be left on

the plate to provide for stamping at least

six retest dates; the plate must be at

least 1⁄16-inch thick and must be

attached by welding, or by brazing. The

brazing rod must melt at a temperature

of 1100 °F. Welding or brazing must be

along all the edges of the plate.

(5) On the neck, neckring, valve boss,

valve protection sleeve, or similar part

permanently attached to the top of the

cylinder.

(6) On the footring permanently

attached to the cylinder, provided the

water capacity of the cylinder does not

exceed 25 pounds.

§ 178.51 Specification 4BA welded or

brazed steel cylinders.

(a) Type, size, and service pressure. A

DOT 4BA cylinder is a cylinder, either

spherical or cylindrical in shape, with a

water capacity of 1,000 pounds or less

and a service pressure of at least 225

and not over 500 pounds per square

inch. Closures made by the spinning

process are not authorized.

(1) Spherical type cylinders must be

made from two seamless hemispheres

joined by the welding of one

circumferential seam.

(2) Cylindrical type cylinders must be

of circumferentially welded or brazed

construction.

(b) Steel. The steel used in the

construction of the cylinder must be as

specified in Table 1 of Appendix A to

this part.

(c) Identification of material. Material

must be identified by any suitable

method except that plates and billets for

hotdrawn cylinders must be marked

with the heat number.

(d) Manufacture. Cylinders must be

manufactured using equipment and

processes adequate to ensure that each

cylinder produced conforms to the

requirements of this subpart. No defect

is permitted that is likely to weaken the

finished cylinder appreciably. A

reasonably smooth and uniform surface

finish is required. Exposed bottom

welds on cylinders over 18 inches long

must be protected by footrings.

(1) Seams must be made as follows:

(i) Minimum thickness of heads and

bottoms must be not less than 90

percent of the required thickness of the

side wall.

(ii) Circumferential seams must be

made by welding or by brazing. Heads

must be attached by brazing and must

have a driving fit with the shell, unless

the shell is crimped, swedged or curled
25962 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

over the skirt or flange of the head and

must be thoroughly brazed until

complete penetration by the brazing

material of the brazed joint is secured.

Depth of brazing from end of the shell

must be at least four times the thickness

of shell metal.

(iii) Longitudinal seams in shells must

be made by copper brazing, copper alloy

brazing, or by silver alloy brazing.

Copper alloy composition must be:

Copper 95 percent minimum, Silicon

1.5 percent to 3.85 percent, Manganese

0.25 percent to 1.10 percent. The

melting point of the silver alloy brazing

material must be in excess of 1,000 °F.

The plate edge must be lapped at least

eight times the thickness of plate, laps

being held in position, substantially

metal to metal, by riveting or by electric

spot-welding. Brazing must be done by

using a suitable flux and by placing

brazing material on one side of seam

and applying heat until this material

shows uniformly along the seam of the

other side. Strength of longitudinal

seam: Copper brazed longitudinal seam

must have strength at least 3⁄2 times the

strength of the steel wall.

(2) Welding procedures and operators

must be qualified in accordance with

CGA Pamphlet C–3.

(e) Welding and brazing. Only the

welding or brazing of neckrings,

footrings, handles, bosses, pads, and

valve protection rings to the tops and

bottoms of cylinders is authorized.

Provided that such attachments and the

portion of the container to which they

are attached are made of weldable steel,

the carbon content of which may not

exceed 0.25 percent except in the case

of 4130× steel which may be used with

proper welding procedure.

(f) Wall thickness. The minimum wall

thickness of the cylinder must meet the

following conditions:

(1) For any cylinder with an outside

diameter of greater than 6 inches, the

minimum wall thickness is 0.078 inch.

In any case the minimum wall thickness

must be such that the calculated wall

stress at the minimum test pressure may

not exceed the lesser value of any of the

following:

(i) The value shown in Table I of

Appendix A to this part, for the

particular material under consideration;

(ii) One-half of the minimum tensile

strength of the material determined as

required in paragraph (j) of this section;

(iii) 35,000 pounds per square inch; or

(iv) Further provided that wall stress

for cylinders having copper brazed

longitudinal seams may not exceed 95

percent of any of the above values.

Measured wall thickness may not

include galvanizing or other protective

coating.

(2) Cylinders that are cylindrical in

shape must have the wall stress

calculated by the formula:

S=[P(1.3D2+0.4d2)]/(D2¥d2)

Where:

S=wall stress in pounds per square inch;

P=minimum test pressure prescribed for

water jacket test;

D=outside diameter in inches;

d=inside diameter in inches.

(3) Cylinders that are spherical in

shape must have the wall stress

calculated by the formula:

S=PD/4tE

Where:

S=wall stress in pounds per square inch;

P=minimum test pressure prescribed for

water jacket test;

D=outside diameter in inches;

t=minimum wall thickness in inches;

E=0.85 (provides 85 percent weld

efficiency factor which must be

applied in the girth weld area and

heat affected zones which zone

must extend a distance of 6 times

wall thickness from center line of

weld);

E=1.0 (for all other areas).

(4) For a cylinder with a wall

thickness less than 0.100 inch, the ratio

of tangential length to outside diameter

may not exceed 4.1.

(g) Heat treatment. Cylinders must be

heat treated in accordance with the

following requirements:

(1) Each cylinder must be uniformly

and properly heat treated prior to test by

the applicable method shown in Table

I of Appendix A to this Part. Heat

treatment must be accomplished after

all forming and welding operations,

except that when brazed joints are used,

heat treatment must follow any forming

and welding operations, but may be

done before, during or after the brazing

operations.

(2) Heat treatment is not required after

the welding or brazing of weldable low

carbon parts to attachments of similar

material which have been previously

welded or brazed to the top or bottom

of cylinders and properly heat treated,

provided such subsequent welding or

brazing does not produce a temperature

in excess of 400° F in any part of the top

or bottom material.

(h) Openings in cylinders. Openings

in cylinders must comply with the

following requirements:

(1) Any opening must be placed on

other than a cylindrical surface.

(2) Each opening in a spherical type

cylinder must be provided with a fitting,

boss, or pad of weldable steel securely

attached to the container by fusion

welding.

(3) Each opening in a cylindrical type

cylinder must be provided with a fitting,

boss, or pad, securely attached to

container by brazing or by welding.

(4) If threads are used, they must

comply with the following:

(i) Threads must be clean-cut, even,

without checks and tapped to gauge.

(ii) Taper threads must be of a length

not less than that specified for American

Standard taper pipe threads.

(iii) Straight threads, having at least 4

engaged threads, must have a tight fit

and a calculated shear strength of at

least 10 times the test pressure of the

cylinder. Gaskets, adequate to prevent

leakage, are required.

(i) Hydrostatic test. Each cylinder

must successfully withstand a

hydrostatic test, as follows:

(1) The test must be by water jacket,

or other suitable method, operated so as

to obtain accurate data. A pressure

gauge must permit reading to an

accuracy of 1 percent. An expansion

gauge must permit reading of total

expansion to an accuracy of either 1

percent or 0.1 cubic centimeter.

(2) Pressure must be maintained for at

least 30 seconds and sufficiently longer

to ensure complete expansion. Any

internal pressure applied after heat

treatment and previous to the official

test may not exceed 90 percent of the

test pressure.

(3) Permanent volumetric expansion

may not exceed 10 percent of the total

volumetric expansion at test pressure.

(4) Cylinders must be tested as

follows:

(i) At least one cylinder selected at

random out of each lot of 200 or less

must be tested as outlined in paragraphs

(i)(1), (i)(2), and (i)(3) of this section to

at least two times service pressure.

(ii) All cylinders not tested as

outlined in paragraph (i)(4)(i) of this

section must be examined under

pressure of at least two times service

pressure and show no defect.

(j) Physical test. A physical test must

be conducted to determine yield

strength, tensile strength, elongation,

and reduction of area of material, as

follows:

(1) The test is required on 2

specimens cut from one cylinder or part

thereof having passed the hydrostatic

test and heat-treated as required, taken

at random out of each lot of 200 or less.

Physical tests for spheres are required

on 2 specimens cut from flat

representative sample plates of the same

heat taken at random from the steel used

to produce the spheres. This flat steel

from which 2 specimens are to be cut

must receive the same heat treatment as

the spheres themselves. Sample plates

must be taken from each lot of 200 or

less spheres.
Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations 25963

(2) Specimens must conform to the

following: (i) A gauge length of 8 inches with a

width not over 11⁄2 inches, or a gauge

length of 2 inches with a width not over

11⁄2 inches, or a gauge length at least 24

times the thickness with a width not

over 6 times the thickness is authorized

when a cylinder wall is not over 3⁄16

inch thick.

(ii) The specimen, exclusive of grip

ends, may not be flattened. Grip ends

may be flattened to within one inch of

each end of the reduced section.

(iii) When size of the cylinder does

not permit securing straight specimens,

the specimens may be taken in any

location or direction and may be

straightened or flattened cold, by

pressure only, not by blows. When

specimens are so taken and prepared,

the inspector’s report must show in

connection with record of physical tests

detailed information in regard to such

specimens. (iv) Heating of a specimen for any

purpose is not authorized. (3) The yield strength in tension must

be the stress corresponding to a

permanent strain of 0.2 percent of the

gauge length. The following conditions

apply: (i) The yield strength must be

determined by either the ‘‘offset’’

method or the ‘‘extension under load’’

method as prescribed in ASTM

Standard E8.

(ii) In using the ‘‘extension under

load’’ method, the total strain (or

‘‘extension under load’’), corresponding

to the stress at which the 0.2 percent

permanent strain occurs may be

determined with sufficient accuracy by

calculating the elastic extension of the

gauge length under appropriate load and

adding thereto 0.2 percent of the gauge

length. Elastic extension calculations

must be based on an elastic modulus of

30,000,000. In the event of controversy,

the entire stress-strain diagram must be

plotted and the yield strength

determined from the 0.2 percent offset. (iii) For the purpose of strain

measurement, the initial strain reference

must be set while the specimen is under

a stress of 12,000 pounds per square

inch, and the strain indicator reading

must be set at the calculated

corresponding strain. (iv) Cross-head speed of the testing

machine may not exceed 1⁄8 inch per

minute during yield strength

determination.

(k) Elongation. Physical test

specimens must show at least a 40

percent elongation for a 2-inch gauge

length or at least 20 percent in other

cases. Except that these elongation

percentages may be reduced

numerically by 2 for 2-inch specimens,

and by 1 in other cases, for each 7,500

pounds per square inch increment of

tensile strength above 50,000 pounds

per square inch to a maximum of four

such increments.

(l) Tests of welds. Except for brazed

seams, welds must be tested as follows:

(1) Tensile test. A specimen must be

cut from one cylinder of each lot of 200

or less, or welded test plate. The welded

test plate must be of one of the heats in

the lot of 200 or less which it represents,

in the same condition and

approximately the same thickness as the

cylinder wall except that in no case

must it be of a lesser thickness than that

required for a quarter size Charpy

impact specimen. The weld must be

made by the same procedures and

subjected to the same heat treatment as

the major weld on the cylinder. The

specimen must be taken from across the

major seam and must be prepared and

tested in accordance with and must

meet the requirements of CGA Pamphlet

C–3. Should this specimen fail to meet

the requirements, specimens may be

taken from two additional cylinders or

welded test plates from the same lot and

tested. If either of the latter specimens

fail to meet the requirements, the entire

lot represented must be rejected. (2) Guided bend test. A root bend test

specimen must be cut from the cylinder

or welded test plate, used for the tensile

test specified in paragraph (l)(1) of this

section. Specimens must be taken from

across the major seam and must be

prepared and tested in accordance with

and must meet the requirements of CGA

Pamphlet C–3. (3) Alternate guided-bend test. This

test may be used and must be as

required by CGA Pamphlet C–3. The

specimen must be bent until the

elongation at the outer surface, adjacent

to the root of the weld, between the

lightly scribed gage lines a to b, must be

at least 20 percent, except that this

percentage may be reduced for steels

having a tensile strength in excess of

50,000 pounds per square inch, as

provided in paragraph (k) of this

section.

(m) Rejected cylinders. Reheat

treatment is authorized for rejected

cylinders. Subsequent thereto, cylinders

must pass all prescribed tests to be

acceptable. Repair of brazed seams by

brazing and welded seams by welding is

authorized.

(n) Markings. Markings must be

stamped plainly and permanently in

one of the following locations on the

cylinder: (1) On shoulders and top heads not

less than 0.087 inch thick.

(2) On side wall adjacent to top head

for side walls not less than 0.090 inch

thick.

(3) On a cylindrical portion of the

shell which extends beyond the

recessed bottom of the cylinder

constituting an integral and nonpressure part of the cylinder.

(4) On a plate attached to the top of

the cylinder or permanent part thereof;

sufficient space must be left on the plate

to provide for stamping at least six retest

dates; the plate must be at least 1⁄16 inch

thick and must be attached by welding,

or by brazing at a temperature of at least

1100 °F., throughout all edges of the

plate.

(5) On the neck, neckring, valve boss,

valve protection sleeve, or similar part

permanently attached to the top of the

cylinder.

(6) On the footring permanently

attached to the cylinder, provided the

water capacity of the cylinder does not

exceed 25 pounds.

§ 178.53 Specification 4D welded steel

cylinders for aircraft use.

(a) Type, size, and service pressure. A

DOT 4D cylinder is a welded steel

sphere (two seamless hemispheres) or

circumferentially welded cylinder (two

seamless drawn shells) with a water

capacity not over 100 pounds and a

service pressure of at least 300 but not

over 500 pounds per square inch.

Cylinders closed in by spinning process

are not authorized.

(b) Steel. Open-hearth or electric steel

of uniform and weldable quality must

be used. Content may not exceed the

following: Carbon, 0.25; phosphorus,

0.045; sulphur, 0.050, except that the

following steels commercially known as

4130X and Type 304, 316, 321, and 347

stainless steels may be used with proper

welding procedure. A heat of steel made

under Table 1 in this paragraph (b),

check chemical analysis of which is

slightly out of the specified range, is

acceptable, if satisfactory in all other

respects, provided the tolerances shown

in Table 2 in this paragraph (b) are not

exceeded, except as approved by the

Associate Administrator. The following

chemical analyses are authorized:

TABLE 1.—4130X STEEL

4130X Percent

Carbon ........................................ 0.25/0.35.

Manganese ................................. 0.40/0.60.

Phosphorus ................................. 0.04 max.

Sulphur ........................................ 0.05 max

Silicon ......................................... 0.15/0.35.

Chromium ................................... 0.80/1.10.

Molybdenum ............................... 0.15/0.25.

Zirconium .................................... None.

Nickel .......................................... None.
25964 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

TABLE 2.—AUTHORIZED STAINLESS STEELS

Stainless steels

304

(percent)

316

(percent)

321

(percent)

347

(percent)

Carbon (max) .................................................................................................... 0.08 0.08 0.08 0.08

Manganese (max) ............................................................................................. 2.00 2.00 2.00 2.00

Phosphorus (max) ............................................................................................ .030 .045 .030 .030

Sulphur (max) ................................................................................................... .030 .030 .030 .030

Silicon (max) ..................................................................................................... .75 1.00 .75 .75

Nickel ................................................................................................................ 8.0/11.0 10.0/14.0 9.0/13.0 9.0/13.0

Chromium ......................................................................................................... 18.0/20.0 16.0/18.0 17.0/20.0 17.0/20.0

Molybdenum ..................................................................................................... ........................ 2.0/3.0 ........................ ........................

Titanium ............................................................................................................ ........................ ........................ (1) ........................

Columbium ........................................................................................................ ........................ ........................ ........................ (2)

1Titanium may not be less than 5C and not more than 0.60%.

2 Columbium may not be less than 10C and not more than 1.0%.

TABLE 3.—CHECK ANALYSIS TOLERANCES

Element Limit or maximum specified

(percent)

Tolerance (percent) over

the maximum limit or

under the minimum limit

Under minimum limitOver maximum limit

Carbon ...................................................................................................... To 0.15 incl ............................................... 0.01 0.01

Over 0.15 to 0.40 incl ............................... .03 .04

Manganese ............................................................................................... To 0.60 incl ............................................... .03 .03

Over 1.15 to 2.50 incl ............................... .05 .05

Phosphorus 1 ............................................................................................. All ranges .................................................. .................... .01

Sulphur ...................................................................................................... All ranges .................................................. .................... .01

Silicon ....................................................................................................... To 0.30 incl ............................................... .02 .03

Over 0.30 to 1.00 incl ............................... .05 .05

Nickel ........................................................................................................ Over 5.30 to 10.00 incl ............................. .10 .10

Over 10.00 to 14.00 incl ........................... .15 .15

Chromium .................................................................................................. To 0.90 incl ............................................... .03 .03

Over 0.90 to 2.10 incl ............................... .05 .05

Over 15.00 to 20.00 incl ........................... .20 .20

Molybdenum .............................................................................................. To 0.20 incl ............................................... .01 .01

Over 0.20 to 0.40 incl ............................... .02 .02

Over 1.75 to 3.0 incl ................................. .10 .10

Titanium .................................................................................................... All ranges .................................................. .05 .05

Columbium ................................................................................................ All ranges .................................................. .05 .05

1 Rephosphorized steels not subject to check analysis for phosphorus.

(c) Identification of material. Material

must be identified by any suitable

method except that plates and billets for

hotdrawn cylinders must be marked

with the heat number.

(d) Manufacture. Cylinders must be

manufactured using equipment and

processes adequate to ensure that each

cylinder produced conforms to the

requirements of this subpart. No defect

is permitted that is likely to weaken the

finished container appreciably. A

reasonably smooth and uniform surface

finish is required. Welding procedures

and operators must be qualified in

accordance with CGA Pamphlet C–3.

(e) Wall thickness. The wall stress at

the minimum test pressure may not

exceed 24,000 pounds per square inch,

except where steels commercially

known as 4130X, types 304, 316, 321,

and 347 stainless steels are used, stress

at the test pressures may not exceed

37,000 pounds per square inch. The

minimum wall thickness for any

container having a capacity of 1,100

cubic inches or less is 0.04 inch. The

minimum wall thickness for any

container having a capacity in excess of

1,100 cubic inches is 0.095 inch.

Calculations must be done by the

following:

(1) Calculation for a ‘‘sphere’’ must be

made by the formula:

S=PD/4tE

Where:

S=wall stress in pounds per square inch;

P=test pressure prescribed for water

jacket test, i.e., at least two times

service pressure, in pounds per

square inch;

D=outside diameter in inches;

t=minimum wall thickness in inches;

E=0.85 (provides 85 percent weld

efficiency factor which must be

applied in the girth weld area and

heat affected zones which zone

must extend a distance of 6 times

wall thickness from center line of

weld);

E=1.0 (for all other areas).

(2) Calculation for a cylinder must be

made by the formula:

S=[P(1.3D2+0.4d2)]/(D2¥dT12)

Where:

S=wall stress in pounds per square inch;

P=test pressure prescribed for water

jacket test, i.e., at least two times

service pressure, in pounds per

square inch;

D=outside diameter in inches;

d=inside diameter in inches.

(f) Heat treatment. The completed

cylinders must be uniformly and

properly heat-treated prior to tests.
Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations 25965

(g) Openings in container. Openings

in cylinders must comply with the

following:

(1) Each opening in the container,

except those for safety devices, must be

provided with a fitting, boss, or pad,

securely attached to the container by

brazing or by welding or by threads. If

threads are used, they must comply

with the following:

(i) Threads must be clean cut, even,

without checks, and tapped to gauge.

(ii) Taper threads must be of a length

not less than that specified for American

Standard taper pipe threads.

(iii) Straight threads, having at least 4

engaged threads, must have a tight fit

and calculated shear strength of at least

10 times the test pressure of the

container. Gaskets, adequate to prevent

leakage, are required.

(2) Closure of a fitting, boss, or pad

must be adequate to prevent leakage.

(h) Hydrostatic test. Each cylinder

must successfully withstand a

hydrostatic test, as follows:

(1) The test must be by water-jacket,

or other suitable method, operated so as

to obtain accurate data. A pressure

gauge must permit a reading to an

accuracy of 1 percent. An expansion

gauge must permit reading of total

expansion to an accuracy of either 1

percent or 0.1 cubic centimeter.

(2) Pressure must be maintained for at

least 30 seconds and sufficiently longer

to ensure complete expansion. Any

internal pressure applied after heattreatment and previous to the official

test may not exceed 90 percent of the

test pressure. If, due to failure of the test

apparatus, the test pressure cannot be

maintained, the test may be repeated at

a pressure increased by 10 percent or

100 pounds per square inch, whichever

is the lower.

(3) Permanent volumetric expansion

may not exceed 10 percent of the total

volumetric expansion at test pressure.

(4) Containers must be tested as

follows:

(i) Each container to at least 2 times

service pressure; or

(ii) One container out of each lot of

200 or less to at least 3 times service

pressure. Others must be examined

under pressure of 2 times service

pressure and show no defects.

(i) Flattening test for spheres and

cylinders. Spheres and cylinders must

be subjected to a flattening test as

follows:

(1) One sphere taken at random out of

each lot of 200 or less must be subjected

to a flattening test as follows:

(i) The test must be performed after

the hydrostatic test.

(ii) The test must be between parallel

steel plates on a press with a welded

seam at right angles to the plates. Any

projecting appurtenances may be cut off

(by mechanical means only) prior to

crushing.

(2) One cylinder taken at random out

of each lot of 200 or less must be

subjected to a flattening test, as follows:

(i) The test must be performed after

the hydrostatic test.

(ii) The test must be between knife

edges, wedge shaped, 60° angle,

rounded to 1⁄2 inch radius. For lots of 30

or less, physical tests are authorized to

be made on a ring at least 8 inches long

cut from each cylinder and subjected to

the same heat treatment as the finished

cylinder.

(j) Physical test and specimens for

spheres and cylinders. Spheres and

cylinders must be subjected to a

physical test as follows:

(1) Physical test for spheres are

required on 2 specimens cut from a flat

representative sample plate of the same

heat taken at random from the steel used

to produce the sphere. This flat steel

from which the 2 specimens are to be

cut must receive the same heattreatment as the spheres themselves.

Sample plates must be taken for each lot

of 200 or less spheres.

(2) Specimens for spheres must have

a gauge length 2 inches with a width not

over 11⁄2 inches, or a gauge length at

least 24 times the thickness with a

width not over 6 times the thickness is

authorized when a wall is not over 3⁄16

inch thick.

(3) Physical test for cylinders is

required on 2 specimens cut from 1

cylinder taken at random out of each lot

of 200 or less. For lots of 30 or less,

physical tests are authorized to be made

on a ring at least 8 inches long cut from

each cylinder and subjected to the same

heat treatment as the finished cylinder.

(4) Specimens for cylinders must

conform to the following:

(i) A gauge length of 8 inches with a

width not over 11⁄2 inches, or a gauge

length of 2 inches with a width not over

11⁄2 inches, or a gauge length at least 24

times the thickness with a width not

over 6 times the thickness is authorized

when a cylinder wall is not over 3⁄16

inch thick.

(ii) The specimen, exclusive of grip

ends, may not be flattened. Grip ends

may be flattened to within 1 inch of

each end of the reduced section. Heating

of the specimen for any purpose is not

authorized.

(5) The yield strength in tension must

be the stress corresponding to a

permanent strain of 0.2 percent of the

gauge length. The following conditions

apply:

(i) The yield strength must be

determined by either the ‘‘offset’’

method or the ‘‘extension under load’’

method as prescribed in ASTM

Standard E8.

(ii) In using the ‘‘extension under

load’’ method, the total strain (or

‘‘extension under load’’) corresponding

to the stress at which the 0.2 percent

permanent strain occurs may be

determined with sufficient accuracy by

calculating the elastic extension of the

gauge length under appropriate load and

adding thereto 0.2 percent of the gauge

length. Elastic extension calculations

must be based on an elastic modulus of

30,000,000. In the event of controversy,

the entire stress-strain diagram must be

plotted and the yield strength

determined from the 0.2 percent offset.

(iii) For the purpose of strain

measurement, the initial strain must be

set while the specimen is under a stress

of 12,000 pounds per square inch and

the strain indicator reading being set at

the calculated corresponding strain.

(iv) Cross-head speed of the testing

machine may not exceed 1⁄8 inch per

minute during yield strength

determination.

(k) Acceptable results for physical

and flattening tests. Either of the

following is an acceptable result:

(1) An elongation of at least 40

percent for a 2 inch gauge length or at

least 20 percent in other cases and yield

strength not over 73 percent of tensile

strength. In this instance, the flattening

test is not required.

(2) An elongation of at least 20

percent for a 2 inch gauge length or 10

percent in other cases. Flattening is

required to 50 percent of the original

outside diameter without cracking.

(l) Rejected cylinders. Reheattreatment is authorized for rejected

cylinders. Subsequent thereto,

containers must pass all prescribed tests

to be acceptable. Repair of welded

seams by welding prior to reheattreatment is authorized.

(m) Marking. Marking on each

container by stamping plainly and

permanently are only authorized where

the metal is at least 0.09 inch thick, or

on a metal nameplate permanently

secured to the container by means other

than soft solder, or by means that would

not reduce the wall thickness.

§ 178.55 Specification 4B240ET welded or

brazed cylinders.

(a) Type, spinning process, size and

service pressure. A DOT 4B240ET

cylinder is a brazed type cylinder made

from electric resistance welded tubing.

The maximum water capacity of this

cylinder is 12 pounds or 333 cubic

inches and the service must be 240

pounds per square inch. The maximum

outside diameter of the shell must be
25966 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

five inches and maximum length of the

shell is 21 inches. Cylinders closed in

by a spinning process are authorized.

(b) Steel. Open-hearth, basic oxygen,

or electric steel of uniform quality must

be used. Plain carbon steel content may

not exceed the following: Carbon, 0.25;

phosphorus, 0.045; sulfur, 0.050. The

addition of other elements for alloying

effect is prohibited.

(c) Identification of material. Material

must be identified by any suitable

method.

(d) Manufacture. Cylinders must be

manufactured using equipment and

processes adequate to ensure that each

cylinder produced conforms to the

requirements of this subpart. No defect

is permitted that is likely to weaken the

finished cylinder appreciably. A

reasonably smooth and uniform surface

finish is required. Heads may be

attached to shells by lap brazing or may

be formed integrally. The thickness of

the bottom of cylinders welded or

formed by spinning is, under no

condition, to be less than two times the

minimum wall thickness of the

cylindrical shell. Such bottom

thicknesses must be measured within an

area bounded by a line representing the

points of contact between the cylinder

and the floor when the cylinder is in a

vertical position. Seams must conform

to the following:

(1) Circumferential seams must be by

brazing only. Heads must be attached to

shells by the lap brazing method and

must overlap not less than four times

the wall thickness. Brazing material

must have a melting point of not less

than 1000° F. Heads must have a driving

fit with the shell unless the shell is

crimped, swedged, or curled over the

skirt or flange of the head and be

thoroughly brazed until complete

penetration of the joint by the brazing

material is secured. Brazed joints may

be repaired by brazing.

(2) Longitudinal seams in shell must

be by electric resistance welded joints

only. No repairs to longitudinal joints is

permitted.

(3) Welding procedures and operators

must be qualified in accordance with

CGA Pamphlet C–3.

(e) Welding or brazing. Only the

attachment, by welding or brazing, to

the tops and bottoms of cylinders of

neckrings, footrings, handles, bosses,

pads, and valve protection rings is

authorized. Provided that such

attachments and the portion of the

container to which they are attached are

made of weldable steel, the carbon

content of which may not exceed 0.25

percent.

(f) Wall thickness. The wall stress

must be at least two times the service

pressure and may not exceed 18,000

pounds per square inch. The minimum

wall thickness is 0.044 inch. Calculation

must be made by the following formula:

S=[P(1.3D2+0.4d2)]/(D2-d2)

Where:

S=wall stress in pounds per square inch;

P=2 times service pressure;

D=outside diameter in inches;

d=inside diameter in inches.

(g) Heat treatment. Heads formed by

drawing or pressing must be uniformly

and properly heat treated prior to tests.

Cylinders with integral formed heads or

bases must be subjected to a

normalizing operation. Normalizing and

brazing operations may be combined,

provided the operation is carried out at

a temperature in excess of the upper

critical temperature of the steel.

(h) Openings in cylinders. Openings

in cylinders must comply with the

following:

(1) Each opening in cylinders, except

those for safety devices, must be

provided with a fitting, boss, or pad,

securely attached to the cylinder by

brazing or by welding or by threads. A

fitting, boss, or pad must be of steel

suitable for the method of attachment

employed, and which need not be

identified or verified as to analysis,

except that if attachment is by welding,

carbon content may not exceed 0.25

percent. If threads are used, they must

comply with the following:

(i) Threads must be clean cut, even

without checks, and tapped to gauge.

(ii) Taper threads to be of length not

less than as specified for American

Standard taper pipe threads.

(iii) Straight threads, having at least 4

engaged threads, to have tight fit and

calculated shear strength at least 10

times the test pressure of the cylinder;

gaskets required, adequate to prevent

leakage.

(2) Closure of a fitting, boss, or pad

must be adequate to prevent leakage.

(i) Hydrostatic test. Each cylinder

must successfully withstand a

hydrostatic test as follows:

(1) The test must be by water-jacket,

or other suitable method, operated so as

to obtain accurate data. The pressure

gauge must permit reading to an

accuracy of 1 percent. The expansion

gauge must permit reading of total

expansion to an accuracy of either 1

percent or 0.1 cubic centimeter.

(2) Pressure must be maintained for at

least 30 seconds and sufficiently longer

to ensure complete expansion. Any

internal pressure applied after heattreatment and previous to the official

test may not exceed 90 percent of the

test pressure. If, due to failure of the test

apparatus, the test pressure cannot be

maintained, the test may be repeated at

a pressure increased by 10 percent or

100 pounds per square inch, whichever

is the lower.

(3) Permanent volumetric expansion

may not exceed 10 percent of total

volumetric expansion at test pressure.

(4) Cylinders must be tested as

follows:

(i) At least one cylinder selected at

random out of each lot of 200 or less

must be tested as outlined in paragraphs

(i)(1), (i)(2), and (i)(3) of this section to

at least two times service pressure.

(ii) All cylinders not tested as

outlined in paragraph (i)(4)(i) of this

section must be examined under

pressure of at least two times service

pressure and show no defect.

(5) Each 1000 cylinders or less

successively produced each day must

constitute a lot. One cylinder must be

selected from each lot and

hydrostatically tested to destruction. If

this cylinder bursts below five times the

service pressure, then two additional

cylinders must be selected and

subjected to this test. If either of these

cylinders fails by bursting below five

times the service pressure then the

entire lot must be rejected. All cylinders

constituting a lot must be of identical

size, construction heat-treatment, finish,

and quality.

(j) Flattening test. Following the

hydrostatic test, one cylinder taken at

random out of each lot of 200 or less,

must be subjected to a flattening test

that is between knife edges, wedge

shaped, 60° angle, rounded to 1⁄2 inch

radius.

(k) Physical test. A physical test must

be conducted to determine yield

strength, tensile strength, elongation,

and reduction of area of material, as

follows:

(1) The test is required on 2

specimens cut from 1 cylinder, or part

thereof heat-treated as required, taken at

random out of each lot of 200 or less in

the case of cylinders of capacity greater

than 86 cubic inches and out of each lot

of 500 or less for cylinders having a

capacity of 86 cubic inches or less.

(2) Specimens must conform to the

following:

(i) A gauge length of 8 inches with a

width not over 11⁄2 inches, a gauge

length of 2 inches with a width not over

11⁄2 inches, or a gauge length at least 24

times the thickness with a width not

over 6 times the thickness is authorized

when a cylinder wall is not over 3⁄16

inch thick.

(ii) The specimen, exclusive of grip

ends, may not be flattened. Grip ends

may be flattened to within one inch of

each end of the reduced section.
Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations 25967

(iii) When size of cylinder does not

permit securing straight specimens, the

specimens may be taken in any location

or direction and may be straightened or

flattened cold by pressure only, not by

blows. When specimens are so taken

and prepared, the inspector’s report

must show in connection with record of

physical tests detailed information in

regard to such specimens.

(iv) Heating of a specimen for any

purpose is not authorized.

(3) The yield strength in tension must

be the stress corresponding to a

permanent strain of 0.2 percent of the

gauge length. The following conditions

apply:

(i) The yield strength must be

determined by either the ‘‘offset’’

method or the ‘‘extension under load’’

method as prescribed in ASTM

Standard E8.

(ii) In using the ‘‘extension under

load’’ method, the total strain (or

‘‘extension under load’’) corresponding

to the stress at which the 0.2 percent

permanent strain occurs may be

determined with sufficient accuracy by

calculating the elastic extension of the

gauge length under appropriate load and

adding thereto 0.2 percent of the gauge

length. Elastic extension calculations

must be based on an elastic modulus of

30,000,000. In the event of controversy,

the entire stress-strain diagram must be

plotted and the yield strength

determined from the 0.2 percent offset.

(iii) For the purpose of strain

measurement, the initial strain must be

set while the specimen is under a stress

of 12,000 pounds per square inch and

the strain indicator reading being set at

the calculated corresponding strain.

(iv) Cross-head speed of the testing

machine may not exceed 1⁄8 inch per

minute during yield strength

determination.

(l) Acceptable results for physical and

flattening tests. Acceptable results for

the physical and flattening tests are an

elongation of at least 40 percent for a 2

inch gauge length or at least 20 percent

in other cases and a yield strength not

over 73 percent of tensile strength. In

this instance the flattening test is

required, without cracking, to six times

the wall thickness with a weld 90° from

the direction of the applied load. Two

rings cut from the ends of length of pipe

used in production of a lot may be used

for the flattening test provided the rings

accompany the lot which they represent

in all thermal processing operations. At

least one of the rings must pass the

flattening test.

(m) Leakage test. All spun cylinders

and plugged cylinders must be tested for

leakage by gas or air pressure after the

bottom has been cleaned and is free

from all moisture, subject to the

following conditions:

(1) Pressure, approximately the same

as but no less than service pressure,

must be applied to one side of the

finished bottom over an area of at least

1⁄16 of the total area of the bottom but

not less than 3⁄4 inch in diameter,

including the closure, for at least 1

minute, during which time the other

side of the bottom exposed to pressure

must be covered with water and closely

examined for indications of leakage.

Except as provided in paragraph (n) of

this section, cylinders which are leaking

must be rejected.

(2) A spun cylinder is one in which

an end closure in the finished cylinder

has been welded by the spinning

process.

(3) A plugged cylinder is one in

which a permanent closure in the

bottom of a finished cylinder has been

effected by a plug.

(4) As a safety precaution, if the

manufacturer elects to make this test

before the hydrostatic test, he should

design his apparatus so that the pressure

is applied to the smallest area

practicable, around the point of closure,

and so as to use the smallest possible

volume of air or gas.

(n) Rejected cylinders. Repairs of

rejected cylinders is authorized.

Cylinders that are leaking must be

rejected, except that:

(1) Spun cylinders rejected under the

provisions of paragraph (m) of this

section may be removed from the spun

cylinder category by drilling to remove

defective material, tapping, and

plugging.

(2) Brazed joints may be rebrazed.

(3) Subsequent to the operations

noted in paragraphs (n)(1) and (n)(2) of

this section, acceptable cylinders must

pass all prescribed tests.

(o) Marking. Markings on each

cylinder must be by stamping plainly

and permanently on shoulder, top head,

neck or valve protection collar which is

permanently attached to the cylinders

and forming an integral part thereof,

provided that cylinders not less than

0.090 inch thick may be stamped on the

side wall adjacent to top head.

§ 178.56 Specification 4AA480 welded

steel cylinders.

(a) Type, size, and service pressure. A

DOT 4AA480 cylinder is a welded steel

cylinder having a water capacity

(nominal) not over 1,000 pounds water

capacity and a service pressure of 480

pounds per square inch. Closures

welded by spinning process not

permitted.

(b) Steel. The limiting chemical

composition of steel authorized by this

specification must be as shown in Table

I of Appendix A to this part.

(c) Identification of material. Material

must be identified by any suitable

method except that plates and billets for

hotdrawn cylinders must be marked

with the heat number.

(d) Manufacture. Cylinders must be

manufactured using equipment and

processes adequate to ensure that each

cylinder produced conforms to the

requirements of this subpart. No defect

is permitted that is likely to weaken the

finished cylinder appreciably. A

reasonably smooth and uniform surface

finish is required. Exposed bottom

welds on cylinders over 18 inches long

must be protected by footrings.

Minimum thickness of heads and

bottoms may not be less than 90 percent

of the required thickness of the side

wall. Seams must be made as follows:

(1) Circumferential seams must be

welded. Brazing is not authorized.

(2) Longitudinal seams are not

permitted.

(3) Welding procedures and operators

must be qualified in accordance with

CGA Pamphlet C–3.

(e) Welding. Only the welding of

neckrings, footrings, bosses, pads, and

valve protection rings to the tops and

bottoms of cylinders is authorized.

Provided that such attachments are

made of weldable steel, the carbon

content of which does not exceed 0.25

percent.

(f) Wall thickness. The wall thickness

of the cylinder must conform to the

following:

(1) For cylinders with an outside

diameter over 5 inches, the minimum

wall thickness is 0.078 inch. In any

case, the minimum wall thickness must

be such that the calculated wall stress

at the minimum test pressure (in

paragraph (i) of this section) may not

exceed the lesser value of either of the

following:

(i) One-half of the minimum tensile

strength of the material determined as

required in paragraph (j) of this section;

or

(ii) 35,000 pounds per square inch.

(2) Calculation must be made by the

formula:

S=[P(1.3D2+0.4d2)]/(D2¥d2)

Where:

S=wall stress in pounds per square inch;

P=minimum test pressure prescribed for

water jacket test;

D=outside diameter in inches;

d=inside diameter in inches.

(3) The ratio of tangential length to

outside diameter may not exceed 4.0 for

cylinders with a wall thickness less than

0.100 inch.

(g) Heat treatment. Each cylinder

must be uniformly and properly heat
25968 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

treated prior to tests. Any suitable heat

treatment in excess of 1100° F is

authorized except that liquid quenching

is not permitted. Heat treatment must be

accomplished after all forming and

welding operations. Heat treatment is

not required after welding weldable low

carbon parts to attachments of similar

material which have been previously

welded to the top or bottom of cylinders

and properly heat treated, provided

such subsequent welding does not

produce a temperature in excess of 400

°F., in any part of the top or bottom

material.

(h) Openings in cylinders. Openings

in cylinders must conform to the

following:

(1) All openings must be in the heads

or bases.

(2) Each opening in the cylinder,

except those for safety devices, must be

provided with a fitting boss, or pad,

securely attached to the cylinder by

welding or by threads. If threads are

used they must comply with the

following:

(i) Threads must be clean-cut, even

without checks and cut to gauge.

(ii) Taper threads to be of length not

less than as specified for American

Standard taper pipe threads.

(iii) Straight threads having at least 6

engaged threads, must have a tight fit

and a calculated shear strength at least

10 times the test pressure of the

cylinder. Gaskets, adequate to prevent

leakage, are required.

(3) Closure of a fitting, boss or pad

must be adequate to prevent leakage.

(i) Hydrostatic test. Each cylinder

must successfully withstand a

hydrostatic test as follows:

(1) The test must be by water jacket,

or other suitable method, operated so as

to obtain accurate data. The pressure

gauge must permit reading to an

accuracy of 1 percent. The expansion

gauge must permit reading of total

expansion to an accuracy of either 1

percent or 0.1 cubic centimeter.

(2) Pressure must be maintained for at

least 30 seconds or sufficiently longer to

assure complete expansion. Any

internal pressure applied after heattreatment and before the official test

may not exceed 90 percent of the test

pressure. If, due to failure of test

apparatus, the test pressure cannot be

maintained, the test may be repeated at

a pressure increased by 10 percent or

100 pounds per square inch, whichever

is lower.

(3) Permanent volumetric expansion

may not exceed 10 percent of the total

volumetric expansion at test pressure.

(4) Cylinders must be tested as

follows:

(i) At least one cylinder selected at

random out of each lot of 200 or less

must be tested as described in

paragraphs (i)(1), (i)(2), and (i)(3) of this

section, to at least two times service

pressure. If a selected cylinder fails,

then two additional specimens must be

selected at random from the same lot

and subjected to the prescribed test. If

either of these fails the test, then each

cylinder in that lot must be so tested;

and

(ii) Each cylinder not tested as

prescribed in paragraph (i)(4)(i) of this

section must be examined under

pressure of at least two times service

pressure and must show no defect. A

cylinder showing a defect must be

rejected unless it may be requalified

under paragraph (m) of this section.

(j) Physical test. A physical test must

be conducted to determine yield

strength, tensile strength, elongation,

and reduction of area of material, as

follows:

(1) The test is required on 2

specimens cut from one cylinder having

passed the hydrostatic test, or part

thereof heat-treated as required, taken at

random out of each lot of 200 or less.

(2) Specimens must conform to the

following:

(i) A gauge length of 8 inches with a

width not over 11⁄2 inches, a gauge

length of 2 inches with a width not over

11⁄2 inches, or a gauge length at least 24

times the thickness with a width not

over 6 times thickness is authorized

when the cylinder wall is not over 3⁄16

inch thick.

(ii) The specimen, exclusive of grip

ends, may not be flattened. Grip ends

may be flattened to within one inch of

each end of the reduced section.

(iii) When size of cylinder does not

permit securing straight specimens, the

specimens may be taken in any location

or direction and may be straightened or

flattened cold, by pressure only, not by

blows. When specimens are so taken

and prepared, the inspector’s report

must show in connection with record of

physical tests detailed information in

regard to such specimens.

(iv) Heating of a specimen for any

purpose is not authorized.

(3) The yield strength in tension must

be the stress corresponding to a

permanent strain of 0.2 percent of the

gauge length. The following conditions

apply:

(i) The yield strength must be

determined by either the ‘‘offset’’

method or the ‘‘extension under load’’

method as prescribed in ASTM

Standard E8.

(ii) In using the ‘‘extension under

load’’ method, the total strain (or

‘‘extension under load’’), corresponding

to the stress at which the 0.2 percent

permanent strain occurs may be

determined with sufficient accuracy by

calculating the elastic extension of the

gauge length under appropriate load and

adding thereto 0.2 percent of the gauge

length. Elastic extension calculations

must be based on an elastic modulus of

30,000,000. In the event of controversy,

the entire stress-strain diagram must be

plotted and the yield strength

determined from the 0.2 percent offset.

(iii) For the purpose of strain

measurement, the initial strain reference

must be set while the specimen is under

a stress of 12,000 pounds per square

inch and the strain indicator reading

being set at the calculated

corresponding strain.

(iv) Cross-head speed of the testing

machine may not exceed 1⁄8 inch per

minute during yield strength

determination.

(k) Elongation. Physical test

specimens must show at least a 40

percent elongation for 2-inch gauge

lengths or at least a 20 percent

elongation in other cases. Except that

these elongation percentages may be

reduced numerically by 2 for 2-inch

specimens and by 1 in other cases for

each 7,500 pounds per square inch

increment of tensile strength above

50,000 pounds per square inch to a

maximum of four such increments.

(l) Tests of welds. Welds must be

tested as follows:

(1) Tensile test. A specimen must be

cut from one cylinder of each lot of 200

or less, or a welded test plate. The

welded test plate must be of one of the

heats in the lot of 200 or less which it

represents, in the same condition and

approximately the same thickness as the

cylinder wall except that it may not be

of a lesser thickness than that required

for a quarter size Charpy impact

specimen. The weld must be made by

the same procedures and subjected to

the same heat treatment as the major

weld on the cylinder. The specimens

must be taken across the major seam

and must be prepared and tested in

accordance with and must meet the

requirements of CGA Pamphlet C–3.

Should this specimen fail to meet the

requirements, specimens may be taken

from two additional cylinders or welded

test plates from the same lot and tested.

If either of the latter specimens fail to

meet the requirements, the entire lot

represented must be rejected.

(2) Guided bend test. A root bend test

specimen must be cut from the cylinder

or a welded test plate, used for the

tensile test specified in paragraph (l)(1)

of this section. Specimens must be taken

from across the major seam and must be

prepared and tested in accordance with
Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations 25969

and must meet the requirements of CGA

Pamphlet C–3.

(3) Alternate guided-bend test. This

test may be used and must be as

required by CGA Pamphlet C–3. The

specimen must be bent until the

elongation at the outer surface, adjacent

to the root of the weld, between the

lightly scribed gage lines-a to b, is at

least 20 percent, except that this

percentage may be reduced for steels

having a tensile strength in excess of

50,000 pounds per square inch, as

provided in paragraph (k) of this

section.

(m) Rejected cylinders. Reheat

treatment of rejected cylinders is

authorized. Subsequent thereto,

cylinders must pass all prescribed tests

to be acceptable. Repair of welded

seams by welding is authorized.

(n) Markings. Markings must be

stamped plainly and permanently in

one of the following locations on the

cylinder:

(1) On shoulders and top heads not

less than 0.087 inch thick.

(2) On neck, valve boss, valve

protection sleeve, or similar part

permanently attached to top end of

cylinder.

(3) On a plate attached to the top of

the cylinder or permanent part thereof:

sufficient space must be left on the plate

to provide for stamping at least six retest

dates: the plate must be at least 1⁄16 inch

thick and must be attached by welding

or by brazing at a temperature of at least

1100° F, throughout all edges of the

plate.

(4) Variations in location of markings

authorized only when necessitated by

lack of space.

§ 178.57 Specification 4L welded insulated

cylinders.

(a) Type, size, service pressure, and

design service temperature. A DOT 4L

cylinder is a fusion welded insulated

cylinder with a water capacity

(nominal) not over 1,000 pounds water

capacity and a service pressure of at

least 40 but not greater than 500 pounds

per square inch conforming to the

following requirements:

(1) For liquefied hydrogen service, the

cylinders must be designed to stand on

end, with the axis of the cylindrical

portion vertical.

(2) The design service temperature is

the coldest temperature for which a

cylinder is suitable. The required design

service temperatures for each cryogenic

liquid is as follows:

Cryogenic liquid Design service temperature

Argon ............. Minus 320 °F or colder.

Helium ........... Minus 452 °F or colder.

Cryogenic liquid Design service temperature

Hydrogen ....... Minus 42 3°F or colder.

Neon .............. Minus 411 °F or colder.

Nitrogen ......... Minus 320 °F or colder.

Oxygen .......... Minus 320 °F or colder.

(b) Material. Material use in the

construction of this specification must

conform to the following:

(1) Inner containment vessel

(cylinder). Designations and limiting

chemical compositions of steel

authorized by this specification must be

as shown in Table 1 in paragraph (o) of

this section.

(2) Outer jacket. Steel or aluminum

may be used subject to the requirements

of paragraph (o)(2) of this section.

(c) Identification of material. Material

must be identified by any suitable

method.

(d) Manufacture. Cylinders must be

manufactured using equipment and

processes adequate to ensure that each

cylinder produced conforms to the

requirements of this subpart and to the

following requirements:

(1) No defect is permitted that is

likely to weaken the finished cylinder

appreciably. A reasonably smooth and

uniform surface finish is required. The

shell portion must be a reasonably true

cylinder.

(2) The heads must be seamless,

concave side to the pressure,

hemispherical or ellipsoidal in shape

with the major diameter not more than

twice the minor diameter. Minimum

thickness of heads may not be less than

90 percent of the required thickness of

the sidewall. The heads must be

reasonably true to shape, have no abrupt

shape changes, and the skirts must be

reasonably true to round.

(3) The surface of the cylinder must

be insulated. The insulating material

must be fire resistant. The insulation on

non-evacuated jackets must be covered

with a steel jacket not less than 0.060-

inch thick or an aluminum jacket not

less than 0.070 inch thick, so

constructed that moisture cannot come

in contact with the insulating material.

If a vacuum is maintained in the

insulation space, the evacuated jacket

must be designed for a minimum

collapsing pressure of 30 psi differential

whether made of steel or aluminum.

The construction must be such that the

total heat transfer, from the atmosphere

at ambient temperature to the contents

of the cylinder, will not exceed 0.0005

Btu per hour, per Fahrenheit degree

differential in temperature, per pound of

water capacity of the cylinder. For

hydrogen, cryogenic liquid service, the

total heat transfer, with a temperature

differential of 520 Fahrenheit degrees,

may not exceed that required to vent 30

SCF of hydrogen gas per hour.

(4) For a cylinder having a design

service temperature colder than minus

320 °F, a calculation of the maximum

weight of contents must be made and

that weight must be marked on the

cylinder as prescribed in § 178.35.

(5) Welding procedures and operators

must be qualified in accordance with

CGA Pamphlet C–3. In addition, an

impact test of the weld must be

performed in accordance with

paragraph (l) of this section as part of

the qualification of each welding

procedure and operator.

(e) Welding. Welding of the cylinder

must be as follows:

(1) All seams of the cylinder must be

fusion welded. A means must be

provided for accomplishing complete

penetration of the joint. Only butt or

joggle butt joints for the cylinder seams

are authorized. All joints in the cylinder

must have reasonably true alignment.

(2) All attachments to the sidewalls

and heads of the cylinder must be by

fusion welding and must be of a

weldable material complying with the

impact requirements of paragraph (l) of

this section.

(3) For welding the cylinder, each

procedure and operator must be

qualified in accordance with the

sections of CGA Pamphlet C–3 that

apply. In addition, impact tests of the

weld must be performed in accordance

with paragraph (l) of this section as part

of the qualification of each welding

procedure and operator.

(4) Brazing, soldering and threading

are permitted only for joints not made

directly to the cylinder body. Threads

must comply with the requirements of

paragraph (h) of this section.

(f) Wall thickness. The minimum wall

thickness of the cylinder must be such

that the calculated wall stress at the

minimum required test pressure may

not exceed the least value of the

following:

(1) 45,000 pounds per square inch.

(2) One-half of the minimum tensile

strength across the welded seam

determined in paragraph (l) of this

section.

(3) One-half of the minimum tensile

strength of the base metal determined as

required in paragraph (j) of this section.

(4) The yield strength of the base

metal determined as required in

paragraph (l) of this section.

(5) Further provided that wall stress

for cylinders having longitudinal seams

may not exceed 85 percent of the above

value, whichever applies.

(6) Calculation must be made by the

following formula:
25970 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

S=[P(1.3D2+0.4d2)]/(D2¥d2)

where:

S=wall stress in pounds per square inch;

P=minimum test pressure prescribed for

pressure test in pounds per square

inch;

D=outside diameter in inches;

d=inside diameter in inches.

(g) Heat treatment. Heat treatment is

not permitted.

(h) Openings in cylinder. Openings in

cylinders must conform to the

following:

(1) Openings are permitted in heads

only. They must be circular and may not

exceed 3 inches in diameter or one third

of the cylinder diameter, whichever is

less. Each opening in the cylinder must

be provided with a fitting, boss or pad,

either integral with, or securely attached

to, the cylinder body by fusion welding.

Attachments to a fitting, boss or pad

may be made by welding, brazing,

mechanical attachment, or threading.

(2) Threads must comply with the

following:

(i) Threads must be clean-cut, even,

without checks and cut to gauge.

(ii) Taper threads to be of a length not

less than that specified for NPT.

(iii) Straight threads must have at

least 4 engaged threads, tight fit and

calculated shear strength at least 10

times the test pressure of the cylinder.

Gaskets, which prevent leakage and are

inert to the hazardous material, are

required.

(i) Pressure test. Each cylinder, before

insulating and jacketing, must be

examined under a pressure of at least 2

times the service pressure maintained

for at least 30 seconds without evidence

of leakage, visible distortion or other

defect. The pressure gauge must permit

reading to an accuracy of 1 percent.

(j) Physical test. A physical test must

be conducted to determine yield

strength, tensile strength, and

elongation as follows:

(1) The test is required on 2

specimens selected from material of

each heat and in the same condition as

that in the completed cylinder.

(2) Specimens must conform to the

following:

(i) A gauge length of 8 inches with a

width not over 11⁄2 inches, a gauge

length of 2 inches with width not over

11⁄2 inches, or a gauge length at least 24

times thickness with a width not over 6

times thickness (authorized when

cylinder wall is not over 1⁄16 inch thick).

(ii) The specimen, exclusive of grip

ends, may not be flattened. Grip ends

may be flattened to within one inch of

each end of the reduced section.

(iii) When size of the cylinder does

not permit securing straight specimens,

the specimens may be taken in any

location or direction and may be

straightened or flattened cold by

pressure only, not by blows. When

specimens are so taken and prepared,

the inspector’s report must show in

connection with record of physical tests

detailed information in regard to such

specimens.

(iv) Heating of a specimen for any

purpose is not authorized.

(3) The yield strength in tension must

be the stress corresponding to a

permanent strain of 0.2 percent of the

gauge length. The following conditions

apply:

(i) The yield strength must be

determined by either the ‘‘offset’’

method or the ‘‘extension under load’’

method as prescribed in ASTM

Standard E8.

(ii) In using the ‘‘extension under

load’’ method, the total strain (or

‘‘extension under load’’), corresponding

to the stress at which the 0.2 percent

permanent strain occurs may be

determined with sufficient accuracy by

calculating the elastic expansion of the

gauge length under appropriate load and

adding thereto 0.2 percent of the gauge

length. Elastic extension calculations

must be based on the elastic modulus of

the material used. In the event of

controversy, the entire stress-strain

diagram must be plotted and the yield

strength determined from the 0.2

percent offset.

(iii) For the purpose of strain

measurement, the initial strain reference

must be set while the specimen is under

a stress of 12,000 pounds per square

inch and the strain indicator reading

being set at the calculated

corresponding strain.

(iv) Cross-head speed of the testing

machine may not exceed 1⁄8 inch per

minute during yield strength

determination.

(k) Acceptable results for physical

tests. Physical properties must meet the

limits specified in paragraph (o)(1),

Table 1, of this section, for the

particular steel in the annealed

condition. The specimens must show at

least a 20 percent elongation for a 2-inch

gage length. Except that the percentage

may be reduced numerically by 2 for

each 7,500 pounds per square inch

increment of tensile strength above

100,000 pounds per square inch to a

maximum of 5 such increments. Yield

strength and tensile strength must meet

the requirements of paragraph (o)(1),

Table 1, of this section.

(l) Tests of welds. Welds must be

tested as follows:

(1) Tensile test. A specimen must be

cut from one cylinder of each lot of 200

or less, or welded test plate. The welded

test plate must be of one of the heats in

the lot of 200 or less which it represents,

in the same condition and

approximately the same thickness as the

cylinder wall except that it may not be

of a lesser thickness than that required

for a quarter size Charpy impact

specimen. The weld must be made by

the same procedures and subjected to

the same heat treatment as the major

weld on the cylinder. The specimen

must be taken across the major seam

and must be prepared and tested in

accordance with and must meet the

requirements of CGA Pamphlet C–3.

Should this specimen fail to meet the

requirements, specimens may be taken

from two additional cylinders or welded

test plates from the same lot and tested.

If either of the latter specimens fails to

meet the requirements, the entire lot

represented must be rejected.

(2) Guided bend test. A ‘‘root’’ bend

test specimen must be cut from the

cylinder or welded test plate, used for

the tensile test specified in paragraph

(l)(1) of this section and from any other

seam or equivalent welded test plate if

the seam is welded by a procedure

different from that used for the major

seam. Specimens must be taken across

the particular seam being tested and

must be prepared and tested in

accordance with and must meet the

requirements of CGA Pamphlet C–3.

(3) Alternate guided-bend test. This

test may be used and must be as

specified in CGA Pamphlet C–3. The

specimen must be bent until the

elongation at the outer surface, adjacent

to the root of the weld, between the

lightly scribed gage lines a to b, is at

least 20 percent, except that this

percentage may be reduced for steels

having a tensile strength in excess of

100,000 pounds per square inch, as

provided in paragraph (c) of this

section.

(4) Impact tests. One set of three

impact test specimens (for each test)

must be prepared and tested for

determining the impact properties of the

deposited weld metal—

(i) As part of the qualification of the

welding procedure.

(ii) As part of the qualification of the

operators.

(iii) For each ‘‘heat’’ of welding rodor

wire used.

(iv) For each 1,000 feet of weld made

with the same heat of welding rod or

wire.

(v) All impact test specimens must be

of the Charpy type, keyhole or milled Unotch, and must conform in all respects

to Figure 3 of ASTM E–23–60. Each set

of impact specimens must be taken

across the weld and have the notch

located in the weld metal. When the
Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations 25971

cylinder material thickness is 2.5 mm or

thicker, impact specimens must be cut

from a cylinder or welded test plate

used for the tensile or bend test

specimens. The dimension along the

axis of the notch must be reduced to the

largest possible of 10 mm, 7.5 mm, 5

mm or 2.5 mm, depending upon

cylinder thickness. When the material

in the cylinder or welded test plate is

not of sufficient thickness to prepare 2.5

mm impact test specimens, 2.5 mm

specimens must be prepared from a

welded test plate made from 1⁄8 inch

thick material meeting the requirements

specified in paragraph (o)(1), Table 1, of

this section and having a carbon

analysis of .05 minimum, but not

necessarily from one of the heats used

in the lot of cylinders. The test piece

must be welded by the same welding

procedure as used on the particular

cylinder seam being qualified and must

be subjected to the same heat treatment.

(vi) Impact test specimens must be

cooled to the design service

temperature. The apparatus for testing

the specimens must conform to the

requirements of ASTM Standard E–23–

60. The test piece, as well as the

handling tongs, must be cooled for a

length of time sufficient to reach the

service temperature. The temperature of

the cooling device must be maintained

within a range of plus or minus 3° F.

The specimen must be quickly

transferred from the cooling device to

the anvil of the testing machine and

broken within a time lapse of not more

than six seconds.

(vii) The impact properties of each set

of impact specimens may not be less

than the values in the following table:

Size of specimen

Minimum

impact

value

required

for avg.

of each

set of

three

specimens

(ft.-lb.)

Minimum

impact

value

permitted

on one

only of a

set of

three

(ft.-lb.)

10 mm×10 mm .............. 15 10

10 mm×7.5 mm ............. 12.5 8.5

10 mm×5 mm ................ 10 7.0

10 mm×2.5 mm ............. 5 3.5

(viii) When the average value of the

three specimens equals or exceeds the

minimum value permitted for a single

specimen and the value for more than

one specimen is below the required

average value, or when the value for one

specimen is below the minimum value

permitted for a single specimen, a retest

of three additional specimens must be

made. The value of each of these retest

specimens must equal or exceed the

required average value. When an erratic

result is caused by a defective specimen,

or there is uncertainty in test procedure,

a retest is authorized.

(m) Radiographic examination.

Cylinders must be subject to a

radiographic examination as follows:

(1) The techniques and acceptability

of radiographic inspection must

conform to the standards set forth in

CGA Pamphlet C–3.

(2) One finished longitudinal seam

must be selected at random from each

lot of 100 or less successively produced

and be radiographed throughout its

entire length. Should the radiographic

examination fail to meet the

requirements of paragraph (m)(1) of this

section, two additional seams of the

same lot must be examined, and if either

of these fail to meet the requirements of

(m)(1) of this section, only those passing

are acceptable.

(n) Rejected cylinders. Reheat

treatment of rejected cylinders is

authorized. Subsequent thereto,

cylinders must pass all prescribed tests

to be acceptable. Welds may be repaired

by suitable methods of fusion welding.

(o) Authorized materials of

construction. Authorized materials of

construction are as follows:

(1) Inner containment vessel

(cylinder). Electric furnace steel of

uniform quality must be used. Chemical

analysis must conform to ASTM A240,

Type 304 Stainless Steel. A heat of steel

made under Table 1 and Table 2 in this

paragraph (o)(1) is acceptable, even

though its check chemical analysis is

slightly out of the specified range, if it

is satisfactory in all other respects,

provided the tolerances shown in Table

3 in this paragraph (o)(1) are not

exceeded. The following chemical

analyses and physical properties are

authorized:

TABLE 1.—AUTHORIZED MATERIALS

Designation

Chemical

analysis, limits in percent

Carbon 1 .................................. 0.08 max.

Manganese .............................. 2.00 max.

Phosphorus ............................. 0.045 max.

Sulphur .................................... 0.030 max.

Silicon ...................................... 1.00 max.

Nickel ....................................... 8.00–10.50.

Chromium ................................ 18.00–20.00.

Molybdenum ............................ None.

Titanium ................................... None.

Columbium .............................. None.

1The carbon analysis must be reported to

the nearest hundredth of one percent.

TABLE 2.—PHYSICAL PROPERTIES

Physical

properties

(annealed)

Tensile strength, p.s.i. (minimum) ....................................... 75,000

Yield strength, p.s.i. (minimum) 30,000

Elongation in 2 inches (minimum) percent .......................... 30.0

Elongation other permissible

gauge lengths (minimum) percent .......................................... 15.0

TABLE 3.—CHECK ANALYSIS TOLERANCES

Elements Limit or specified range (percent)

Tolerance

over the

maximum

limit or under

the minimum

limit

Carbon ............................................................................................................................ To 0.030, incl ............................................ 0.005

Over 0.30 to 0.20, incl .............................. 0.01

Manganese ..................................................................................................................... To 1.00 incl ............................................... .03

Over 1.00 to 3.00, incl .............................. 0.04

Phosphorus 1 ................................................................................................................... To 0.040, incl ............................................ 0.005

Over 0.040 to 0.020 incl ........................... 0.010

Sulphur ........................................................................................................................... To .40 incl ................................................. 0.005
25972 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

TABLE 3.—CHECK ANALYSIS TOLERANCES—Continued

Elements Limit or specified range (percent)

Tolerance

over the

maximum

limit or under

the minimum

limit

Silicon ............................................................................................................................. To 1.00, incl .............................................. 0.05

Nickel .............................................................................................................................. Over 5.00 to 10.00, incl ............................ 0.10

Over 10.00 to 20.00, incl .......................... 0.15

Chromium ....................................................................................................................... Over 15.00 to 20.00, incl .......................... 0.20

1 Rephosphorized steels not subject to check analysis for phosphorus.

(2) Outer jacket. (i) Nonflammable

cryogenic liquids. Cylinders intended

for use in the transportation of

nonflammable cryogenic liquid must

have an outer jacket made of steel or

aluminum.

(ii) Flammable cryogenic liquids.

Cylinders intended for use in the

transportation of flammable cryogenic

liquid must have an outer jacket made

of steel.

(p) Markings. (1) Markings must be

stamped plainly and permanently on

shoulder or top head of jacket or on a

permanently attached plate or head

protective ring.

(2) The letters ‘‘ST’’, followed by the

design service temperature (for example,

ST–423F), must be marked on cylinders

having a design service temperature of

colder than minus 320° F only. Location

to be just below the DOT mark.

(3) The maximum weight of contents,

in pounds (for example, ‘‘Max. Content

51 #’’), must be marked on cylinders

having a design service temperature

colder than minus 320° F only. Location

to be near symbol.

(4) Special orientation instructions

must be marked on the cylinder (for

example, THIS END UP), if the cylinder

is used in an orientation other than

vertical with openings at the top of the

cylinder.

(5) If the jacket of the cylinder is

constructed of aluminum, the letters

‘‘AL’’ must be marked after the service

pressure marking. Example: DOT–4L150

AL.

(6) Except for serial number and

jacket material designation, each

marking prescribed in this paragraph (p)

must be duplicated on each cylinder by

any suitable means.

(q) Inspector’s report. In addition to

the information required by § 178.35,

the inspector’s reports must contain

information on:

(1) The jacket material and insulation

type;

(2) The design service temperature

(°F); and

(3) The impact test results, on a lot

basis.

§ 178.58 Specification 4DA welded steel

cylinders for aircraft use.

(a) Type, size, and service pressure. A

DOT 4DA is a welded steel sphere (two

seamless hemispheres) or a

circumferentially welded cylinder (two

seamless drawn shells) with a water

capacity not over 100 pounds and a

service pressure of at least 500 but not

over 900 pounds per square inch.

(b) Steel. Open-hearth or electric steel

of uniform quality must be used. A heat

of steel made under Table 1 in this

paragraph (b), check chemical analysis

of which is slightly out of the specified

range, is acceptable, if satisfactory in all

other respects, provided the tolerances

shown in Table 2 in this paragraph (b)

are not exceeded except as approved by

the Associate Administrator. The

following chemical analyses are

authorized:

TABLE 1.—AUTHORIZED MATERIALS

4130 Percent

Carbon .................................................................................................................................................................................................... 0.28/0.33.

Manganese ............................................................................................................................................................................................. 0.40/0.60.

Phosphorus ............................................................................................................................................................................................ 0.040 max.

Sulfur ...................................................................................................................................................................................................... 0.040 max.

Silicon ..................................................................................................................................................................................................... 0.15/0.35.

Chromium ............................................................................................................................................................................................... 0.80/1.10.

Molybdenum ........................................................................................................................................................................................... 0.15/0.25.

TABLE 2.—CHECK ANALYSIS TOLERANCES

Element Limit or maximum specified (percent)

Tolerance (percent) over

the maximum limit or

under the minimum limit

Under minimum limitOver maximum limit

Carbon ...................................................................................................... Over 0.15 to 0.40 incl ............................... .03 .04

Manganese ............................................................................................... To 0.60 incl ............................................... .03 .03

Phosphorus1 ............................................................................................. All ranges .................................................. .................... .01

Sulphur ...................................................................................................... All ranges .................................................. .................... .01

Silicon ....................................................................................................... To 0.30 incl ............................................... .02 .03

Over 0.30 to 1.00 incl ............................... .05 .05

Chromium .................................................................................................. To 0.90 incl ............................................... .03 .03

Over 0.90 to 2.10 incl ............................... .05 .05

Molybdenum .............................................................................................. To 0.20 incl ............................................... .01 .01
Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations 25973

TABLE 2.—CHECK ANALYSIS TOLERANCES—Continued

Element Limit or maximum specified (percent)

Tolerance (percent) over

the maximum limit or

under the minimum limit

Under minimum limitOver maximum limit

Over 0.20 to 0.40, incl .............................. .02 .02

1 Rephosphorized steels not subject to check analysis for phosphorus.

(c) Identification of material.

Materials must be identified by any

suitable method except that plates and

billets for hot-drawn containers must be

marked with the heat number.

(d) Manufacture. Cylinders must be

manufactured in accordance with the

following requirements:

(1) By best appliances and methods.

No defect is acceptable that is likely to

weaken the finished container

appreciably. A reasonably smooth and

uniform surface finish is required. No

abrupt change in wall thickness is

permitted. Welding procedures and

operators must be qualified in

accordance with CGA Pamphlet C–3.

(2) All seams of the sphere or

cylinders must be fusion welded. Seams

must be of the butt or joggle butt type

and means must be provided for

accomplishing complete penetration of

the joint.

(e) Welding. Attachments to the

container are authorized by fusion

welding provided that such attachments

are made of weldable steel, the carbon

content of which may not exceed 0.25

percent except in the case of 4130 steel.

(f) Wall thickness. The minimum wall

thickness must be such that the wall

stress at the minimum specified test

pressure may not exceed 67 percent of

the minimum tensile strength of the

steel as determined from the physical

and burst tests required and may not be

over 70,000 p.s.i. For any diameter

container, the minimum wall thickness

is 0.040 inch. Calculations must be

made by the formulas in (f)(1) or (f)(2)

of this section:

(1) Calculation for a sphere must be

made by the following formula:

S=PD/4tE

Where:

S=wall stress in pounds per square inch;

P=test pressure prescribed for water

jacket test, i.e., at least 2 times

service pressure, in pounds per

square inch;

D=outside diameter in inches;

t=minimum wall thickness in inches;

E=0.85 (provides 85 percent weld

efficiency factor which must be

applied in the girth weld area and

heat affected zones which zone

must extend a distance of 6 times

wall thickness from center line of

weld);

E=1.0 (for all other areas).

(2) Calculation for a cylinder must be

made by the following formula:

S=[P(1.3D 2+0.4d 2)]/(D 2¥d 2)

Where:

S=wall stress in pounds per square inch;

P=test pressure prescribed for water

jacket test, i.e., at least 2 times

service pressure, in pounds per

square inch;

D=outside diameter in inches;

d=inside diameter in inches.

(g) Heat treatment. The completed

containers must be uniformly and

properly heat-treated prior to tests.

Heat-treatment of containers of the

authorized analysis must be as follows:

(1) All containers must be quenched

by oil, or other suitable medium except

as provided in paragraph (g)(4) of this

section.

(2) The steel temperature on

quenching must be that recommended

for the steel analysis, but may not

exceed 1,750° F.

(3) The steel must be tempered at the

temperature most suitable for the

analysis except that in no case shall the

tempering temperature be less than

1,000° F.

(4) The steel may be normalized at a

temperature of 1,650° F instead of being

quenched, and containers so normalized

need not be tempered.

(5) All cylinders, if water quenched or

quenched with a liquid producing a

cooling rate in excess of 80 percent of

the cooling rate of water, must be

inspected by the magnetic particle or

dye penetrant method to detect the

presence of quenching cracks. Any

cylinder found to have a quench crack

must be rejected and may not be

requalified.

(h) Openings in container. Openings

in the container must comply with the

following requirements:

(1) Each opening in the container

must be provided with a fitting, boss, or

pad of weldable steel securely attached

to the container by fusion welding.

(2) Attachments to a fitting, boss, or

pad must be adequate to prevent

leakage. Threads must comply with the

following:

(i) Threads must be clean cut, even,

without checks, and tapped to gauge.

(ii) Taper threads to be of length not

less than as specified for American

Standard taper pipe threads.

(iii) Straight threads, having at least 4

engaged threads, to have tight fit and

calculated shear strength at least 10

times the test pressure of the container;

gaskets required, adequate to prevent

leakage.

(i) Hydrostatic test. Each cylinder

must successfully withstand a

hydrostatic test as follows:

(1) The test must be by water-jacket,

or other suitable method, operated so as

to obtain accurate data. The pressure

gauge must permit reading to an

accuracy of 1 percent. The expansion

gauge must permit reading of total

expansion to accuracy either of 1

percent or 0.1 cubic centimeter.

(2) Pressure must be maintained for at

least 30 seconds and sufficiently longer

to ensure complete expansion. Any

internal pressure applied after heattreatment and previous to the official

test may not exceed 90 percent of the

test pressure. If, due to failure of the test

apparatus, the test pressure cannot be

maintained, the test may be repeated at

a pressure increased by 10 percent or

100 pounds per square inch, whichever

is the lower.

(3) Permanent volumetric expansion

may not exceed 10 percent of total

volumetric expansion at test pressure.

(4) Each container must be tested to

at least 2 times service pressure.

(j) Burst test. One container taken at

random out of 200 or less must be

hydrostatically tested to destruction.

The rupture pressure must be included

as part of the inspector’s report.

(k) Flattening test. Spheres and

cylinders must be subjected to a

flattening test as follows:

(1) Flattening test for spheres. One

sphere taken at random out of each lot

of 200 or less must be subjected to a

flattening test as follows:

(i) The test must be performed after

the hydrostatic test.

(ii) The test must be at the weld

between the parallel steel plates on a
25974 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

press with a welded seam, at right

angles to the plates. Any projecting

appurtenances may be cut off (by

mechanical means only) prior to

crushing.

(2) Flattening test for cylinders. One

cylinder taken at random out of each lot

of 200 or less, must be subjected to a

flattening test as follows:

(i) The test must be performed after

the hydrostatic test.

(ii) The test must between knife edges,

wedge shaped, 60° angle, rounded to 1⁄2

inch radius; test

(l) Radiographic inspection.

Radiographic examinations is required

on all welded joints which are subjected

to internal pressure, except that at the

discretion of the disinterested inspector,

openings less than 25 percent of the

sphere diameter need not be subjected

to radiographic inspection. Evidence of

any defects likely to seriously weaken

the container must be cause for

rejection.

(m) Physical test and specimens for

spheres and cylinders. Spheres and

cylinders must be subjected to a

physical test as follows:

(1) A physical test for a sphere is

required on 2 specimens cut from a flat

representative sample plate of the same

heat taken at random from the steel used

to produce the sphere. This flat steel

from which the 2 specimens are to be

cut must receive the same heattreatment as the spheres themselves.

Sample plates to be taken for each lot

of 200 or less spheres.

(2) Specimens for spheres have a

gauge length of 2 inches with a width

not over 11⁄2 inches, or a gauge length

at least 24 times thickness with a width

not over 6 times thickness is authorized

when wall of sphere is not over 3⁄16 inch

thick.

(3) A physical test for cylinders is

required on 2 specimens cut from 1

cylinder taken at random out of each lot

of 200 or less.

(4) Specimens for cylinder must

conform to the following:

(i) A gauge length of 8 inches with a

width not over 11⁄2 inches, a gauge

length of 2 inches with a width not over

11⁄2 inches, a gauge length at least 24

times thickness with a width not over 6

times thickness is authorized when a

cylinder wall is not over 3⁄16 inch thick.

(ii) The specimen, exclusive of grip

ends, may not be flattened. Grip ends

may be flattened to within 1 inch of

each end of the reduced section.

(iii) Heating of a specimen for any

purpose is not authorized.

(5) The yield strength in tension must

be the stress corresponding to a

permanent strain of 0.2 percent of the

gauge length. The following conditions

apply:

(i) The yield strength must be

determined by either the ‘‘offset’’

method or the ‘‘extension under load’’

method as prescribed in ASTM

Standard E8.

(ii) In using the ‘‘extension under

load’’ method, the total strain (or

‘‘extension under load’’) corresponding

to the stress at which the 0.2 percent

permanent strain occurs may be

determined with sufficient accuracy by

calculating the elastic extension of the

gauge length under appropriate load and

adding thereto 0.2 percent of the gauge

length. Elastic extension calculations

must be based on an elastic modulus of

30,000,000. In the event of controversy,

the entire stress-strain diagram must be

plotted and the yield strength

determined from the 0.2 percent offset.

(iii) For the purpose of strain

measurement, the initial strain must be

set while the specimen is under a stress

of 12,000 pounds per square inch and

the strain indicator reading being set at

the calculated corresponding strain.

(iv) Cross-head speed of the testing

machine may not exceed 1⁄8 inch per

minute during yield strength

determination.

(n) Acceptable results for physical,

flattening, and burst tests. The following

are acceptable results of the physical,

flattening and burst test:

(1) Elongation must be at least 20

percent for a 2-inch gauge length or 10

percent in other cases.

(2) Flattening is required to 50 percent

of the original outside diameter without

cracking.

(3) Burst pressure must be at least 3

times service pressure.

(o) Rejected containers. Reheattreatment of rejected cylinders is

authorized. Subsequent thereto,

containers must pass all prescribed tests

to be acceptable. Repair of welded

seams by welding prior to reheattreatment is authorized.

(p) Marking. Markings on each

container must be stamped plainly and

permanently on a permanent attachment

or on a metal nameplate permanently

secured to the container by means other

than soft solder.

§ 178.59 Specification 8 steel cylinders

with porous fillings for acetylene.

(a) Type and service pressure. A DOT

8 cylinder is a seamless cylinder with a

service pressure of 250 pounds per

square inch. The following steel is

authorized:

(1) A longitudinal seam if forge lap

welded;

(2) Attachment of heads by welding or

by brazing by dipping process; or

(3) A welded circumferential body

seam if the cylinder has no longitudinal

seam.

(b) Steel. Open-hearth, electric or

basic oxygen process steel of uniform

quality must be used. Content percent

may not exceed the following: Carbon,

0.25; phosphorus, 0.045; sulphur, 0.050.

(c) Identification of steel. Materials

must be identified by any suitable

method except that plates and billets for

hot-drawn cylinders must be marked

with the heat number.

(d) Manufacture. Cylinders must be

manufactured using equipment and

processes adequate to ensure that each

cylinder produced conforms to the

requirements of this subpart. No defect

is acceptable that is likely to weaken the

finished cylinder appreciably. A

reasonably smooth and uniform surface

finish is required. Welding procedures

and operators must be qualified in

accordance with CGA Pamphlet C–3.

(e) Exposed bottom welds. Exposed

bottom welds on cylinders over 18

inches long must be protected by

footrings.

(f) Heat treatment. Body and heads

formed by drawing or pressing must be

uniformly and properly heat treated

prior to tests.

(g) Openings. Openings in the

cylinders must comply with the

following:

(1) Standard taper pipe threads are

required;

(2) Length may not be less than as

specified for American Standard pipe

threads; tapped to gauge; clean cut,

even, and without checks.

(h) Hydrostatic test. Each cylinder

must successfully withstand a

hydrostatic test as follows:

(1) The test must be by water-jacket,

or other suitable method, operated so as

to obtain accurate data. The pressure

gauge must permit reading to an

accuracy of 1 percent. The expansion

gauge must permit reading of total

expansion to an accuracy of either 1

percent or 0.1 cubic centimeter.

(2) Pressure must be maintained for at

least 30 seconds and sufficiently longer

to ensure complete expansion. Any

internal pressure applied after heattreatment and previous to the official

test may not exceed 90 percent of the

test pressure.

(3) Permanent volumetric expansion

may not exceed 10 percent of total

volumetric expansion at test pressure.

(4) One cylinder out of each lot of 200

or less must be hydrostatically tested to

at least 750 pounds per square inch.

Cylinders not so tested must be

examined under pressure of between

500 and 600 pounds per square inch

and show no defect. If hydrostatically
Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations 25975

tested cylinder fails, each cylinder in

the lot may be hydrostatically tested and

those passing are acceptable.

(i) Leakage test. Cylinders with

bottoms closed in by spinning must be

subjected to a leakage test by setting the

interior air or gas pressure to not less

than the service pressure. Cylinders

which leak must be rejected.

(j) Physical test. A physical test must

be conducted as follows:

(1) The test is required on 2

specimens cut longitudinally from 1

cylinder or part thereof taken at random

out of each lot of 200 or less, after heat

treatment.

(2) Specimens must conform to a

gauge length of 8 inches with a width

not over 11⁄2 inches, a gauge length of

2 inches with width not over 11⁄2, or a

gauge length at least 24 times thickness

with a width not over 6 times thickness

is authorized when a cylinder wall is

not over 3⁄16 inch thick.

(3) The yield strength in tension must

be the stress corresponding to a

permanent strain of 0.2 percent of the

gauge length. The following conditions

apply:

(i) The yield strength must be

determined by either the ‘‘offset’’

method or the ‘‘extension under load’’

method as prescribed in ASTM

Standard E8.

(ii) In using the ‘‘extension under

load’’ method, the total strain (or

‘‘extension under load’’) corresponding

to the stress at which the 0.2 percent

permanent strain occurs may be

determined with sufficient accuracy by

calculating the elastic extension of the

gauge length under appropriate load and

adding thereto 0.2 percent of the gauge

length. Elastic extension calculations

must be based on an elastic modulus of

30,000,000. In the event of controversy,

the entire stress-strain diagram must be

plotted and the yield strength

determined from the 0.2 offset.

(iii) For the purpose of strain

measurement, the initial strain must be

set while the specimen is under a stress

of 12,000 pounds per square inch and

the strain indicator reading being set at

the calculated corresponding strain.

(iv) Cross-head speed of the testing

machine may not exceed 1⁄8 inch perminute during yield strength

determination.

(4) Yield strength may not exceed 73

percent of tensile strength. Elongation

must be at least 40 percent in 2 inch or

20 percent in other cases.

(k) Rejected cylinders. Reheat

treatment of rejected cylinder is

authorized. Subsequent thereto,

cylinders must pass all prescribed tests

to be acceptable. Repair by welding is

authorized.

(l) Porous filling. (1) Cylinders must

be filled with a porous material in

accordance with the following:

(i) The porous material may not

disintegrate or sag when wet with

solvent or when subjected to normal

service;

(ii) The porous filling material must

be uniform in quality and free of voids,

except that a well drilled into the filling

material beneath the valve is authorized

if the well is filled with a material of

such type that the functions of the

filling material are not impaired;

(iii) Overall shrinkage of the filling

material is authorized if the total

clearance between the cylinder shell

and filling material, after solvent has

been added, does not exceed 1⁄2 of 1

percent of the respective diameter or

length, but not to exceed 1⁄8 inch,

measured diametrically and

longitudinally;

(iv) The clearance may not impair the

functions of the filling material;

(v) The installed filling material must

meet the requirements of CGA Pamphlet

C–12; and

(vi) Porosity of filling material may

not exceed 80 percent except that filling

material with a porosity of up to 92

percent may be used when tested with

satisfactory results in accordance with

CGA Pamphlet C–12.

(2) When the porosity of each cylinder

is not known, a cylinder taken at

random from a lot of 200 or less must

be tested for porosity. If the test cylinder

fails, each cylinder in the lot may be

tested individually and those cylinders

that pass the test are acceptable.

(3) For filling that is molded and

dried before insertion in cylinders,

porosity test may be made on a sample

block taken at random from material to

be used.

(4) The porosity of the filling material

must be determined. The amount of

solvent at 70° F for a cylinder:

(i) Having shell volumetric capacity

above 20 pounds water capacity

(nominal) may not exceed the following:

Percent porosity of filler

Maximum

acetone solvent percent

shell capacity by volume

90 to 92 ..................................... 43.4

87 to 90 ..................................... 42.0

83 to 87 ..................................... 40.0

80 to 83 ..................................... 38.6

75 to 80 ..................................... 36.2

70 to 75 ..................................... 33.8

65 to 70 ..................................... 31.4

(ii) Having volumetric capacity of 20

pounds or less water capacity (nominal),

may not exceed the following:

Percent porosity of filler

Maximum

acetone solvent percent

shell capacity by volume

90 to 92 ..................................... 41.8

83 to 90 ..................................... 38.5

80 to 83 ..................................... 37.1

75 to 80 ..................................... 34.8

70 to 75 ..................................... 32.5

65 to 70 ..................................... 30.2

(m) Tare weight. The tare weight is

the combined weight of the cylinder

proper, porous filling, valve, and

solvent, without removable cap.

(n) Duties of inspector. In addition to

the requirements of § 178.35, the

inspector is required to—

(1) Certify chemical analyses of steel

used, signed by manufacturer thereof;

also verify by, check analyses of

samples taken from each heat or from 1

out of each lot of 200 or less, plates,

shells, or tubes used.

(2) Verify compliance of cylinder

shells with all shell requirements;

inspect inside before closing in both

ends; verify heat treatment as proper;

obtain all samples for all tests and for

check analyses; witness all tests; verify

threads by gauge; report volumetric

capacity and minimum thickness of

wall noted.

(3) Prepare report on manufacture of

steel shells in form prescribed in

§ 178.35. Furnish one copy to

manufacturer and three copies to the

company that is to complete the

cylinders.

(4) Determine porosity of filling and

tare weights; verify compliance of

marking with prescribed requirements;

obtain necessary copies of steel shell

reports; and furnish complete reports

required by this specification to the

person who has completed the

manufacture of the cylinders and, upon

request, to the purchaser. The test

reports must be retained by the

inspector for fifteen years from the

original test date of the cylinder.

(o) Marking. (1) Marking on each

cylinder must be stamped plainly and

permanently on or near the shoulder,

top head, neck or valve protection collar

which is permanently attached to the

cylinder and forming integral part

thereof.

(2) Tare weight of cylinder, in pounds

and ounces, must be marked on the

cylinder.

(3) Cylinders, not completed, when

delivered must each be marked for

identification of each lot of 200 or less.
25976 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

§ 178.60 Specification 8AL steel cylinders

with porous fillings for acetylene.

(a) Type and service pressure. A DOT

8AL cylinder is a seamless steel

cylinder with a service pressure of 250

pounds per square inch. However, the

attachment of heads by welding or by

brazing by dipping process and a

welded circumferential body seam is

authorized. Longitudinal seams are not

authorized.

(b) Authorized steel. The authorized

steel is as specified in Table I of

Appendix A to this part.

(c) Identification of steel. Material

must be identified by any suitable

method except that plates and billets for

hot-drawn cylinders must be marked

with heat number.

(d) Manufacture. Cylinders must be

manufactured using equipment and

processes adequate to ensure that each

cylinder produced conforms to the

requirements of this subpart. No defect

is permitted that is likely to weaken the

finished cylinder appreciably. A

reasonably smooth and uniform surface

finish is required. Welding procedures

and operators must be qualified in

accordance with CGA Pamphlet C–3.

(e) Footrings. Exposed bottom welds

on cylinders over 18 inches long must

be protected by footrings.

(f) Welding or brazing. Welding or

brazing for any purpose whatsoever is

prohibited except as follows:

(1) The attachment to the tops or

bottoms of cylinders of neckrings,

footrings, handlers, bosses, pads, and

valve protecting rings is authorized

provided that such attachments and the

portion of the container to which they

are attached are made of weldable steel,

the carbon content of which may not

exceed 0.25 percent.

(2) Heat treatment is not required after

welding or brazing weldable low carbon

parts to attachments, specified in

paragraph (f)(1) of this section, of

similar material which have been

previously welded or brazed to the top

or bottom of cylinders and properly heat

treated, provided such subsequent

welding or brazing does not produce a

temperature in excess of 400° F in any

part of the top or bottom material.

(g) Wall thickness; wall stress. The

wall thickness/wall stress of the

cylinder must conform to the following:

(1) The calculated wall stress at 750

pounds per square inch may not exceed

35,000 pounds per square inch, or onehalf of the minimum ultimate strength

of the steel as determined in paragraph

(l) of this section, whichever value is the

smaller. The measured wall thickness

may not include galvanizing or other

protective coating.

(i) Calculation of wall stress must be

made by the formula:

S=[P(1.3D2+0.4d2)]/(D2¥d2)

Where:

S=wall stress in pounds per square inch;

P=750 pounds per square inch

(minimum test pressure);

D=outside diameter in inches;

d=inside diameter in inches.

(ii) Either D or d must be calculated

from the relation D = d + 2t, where t =

minimum wall thickness.

(2) Cylinders with a wall thickness

less than 0.100 inch, the ratio of straight

side wall length to outside diameter

may not exceed 3.5.

(3) For cylinders having outside

diameter over 5 inches, the minimum

wall thickness must be 0.087 inch.

(h) Heat treatment. Each cylinder

must be uniformly and properly heat

treated, prior to tests, by any suitable

method in excess of 1100° F. Heat

treatment must be accomplished after

all forming and welding operations,

except that when brazed joints are used,

heat treatment must follow any forming

and welding operations but may be

done before, during, or after the brazing

operations. Liquid quenching is not

authorized.

(i) Openings. Standard taper pipe

threads required in all openings. The

length of the opening may not be less

than as specified for American Standard

pipe threads; tapped to gauge; clean cut,

even, and without checks.

(j) Hydrostatic test. Each cylinder

must successfully withstand a

hydrostatic test as follows:

(1) The test must be by water-jacket,

or other suitable method, operated so as

to obtain accurate data. The pressure

gauge must permit reading to an

accuracy of 1 percent. The expansion

gauge must permit reading of total

expansion to an accuracy of either 1

percent or 0.1 cubic centimeter.

(2) Pressure must be maintained for at

least 30 seconds and sufficiently longer

to ensure complete expansion. Any

internal pressure applied after heattreatment and previous to the official

test may not exceed 90 percent of the

test pressure.

(3) Permanent volumetric expansion

may not exceed 10 percent of total

volumetric expansion at test pressure.

(4) One cylinder out of each lot of 200

or less must be hydrostatically tested to

at least 750 pounds per square inch.

Cylinders not so tested must be

examined under pressure of between

500 and 600 pounds per square inch

and show no defect. If a hydrostatically

tested cylinder fails, each cylinder in

the lot may be hydrostatically tested and

those passing are acceptable.

(k) Leakage test. Cylinders with

bottoms closed in by spinning must be

leakage tested by setting the interior air

or gas pressure at not less than the

service pressure. Any cylinder that leaks

must be rejected.

(l) Physical test. A physical test must

be conducted as follows;

(1) The test is required on 2

specimens cut longitudinally from 1

cylinder or part thereof taken at random

out of each lot of 200 or less, after heat

treatment.

(2) Specimens must conform to a

gauge length of 8 inches with a width

not over 11⁄2 inches, a gauge length 2

inches with a width not over 1 1⁄2

inches, or a gauge length at least 24

times thickness with a width not over 6

times thickness is authorized when a

cylinder wall is not over 3⁄16 inch thick.

(3) The yield strength in tension must

be the stress corresponding to a

permanent strain of 0.2 percent of the

gauge length. The following conditions

apply:

(i) The yield strength must be

determined by either the ‘‘offset’’

method or the ‘‘extension under load’’

method as prescribed in ASTM

Standard E 8.

(ii) In using the ‘‘extension under

load’’ method, the total strain (or

‘‘extension under load’’) corresponding

to the stress at which the 0.2 percent

permanent strain occurs may be

determined with sufficient accuracy by

calculating the elastic extension of the

gauge length under appropriate load and

adding thereto 0.2 percent of the gauge

length. Elastic extension calculations

must be based on an elastic modulus of

30,000,000. In the event of controversy,

the entire stress-strain diagram must be

plotted and the yield strength

determined from the 0.2 offset.

(iii) For the purpose of strain

measurement, the initial strain must be

set while the specimen is under a stress

of 12,000 pounds per square inch, the

strain indicator reading being set at the

calculated corresponding strain.

(iv) Cross-head speed of the testing

machine may not exceed 1⁄8 inch per

minute during yield strength

determination.

(m) Elongation. Physical test

specimens must show at least a 40

percent elongation for a 2 inch gauge

length or at least a 20 percent elongation

in other cases. Except that these

elongation percentages may be reduced

numerically by 2 for 2 inch specimens

and 1 in other cases for each 7,500

pounds per square inch increment of

tensile strength above 50,000 pounds

per square inch to a maximum of four

such increments.
Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations 25977

(n) Weld tests. Specimens taken

across the circumferentially welded

seam must be cut from one cylinder

taken at random from each lot of 200 or

less cylinders after heat treatment and

must pass satisfactorily the following

tests:

(1) Tensile test. A specimen must be

cut from one cylinder of each lot of 200

or less, or welded test plate. The

specimen must be taken from across the

major seam and must be prepared and

tested in accordance with and must

meet the requirements of CGA Pamphlet

C–3. Should this specimen fail to meet

the requirements, specimens may be

taken from two additional cylinders or

welded test plates from the same lot and

tested. If either of the latter specimens

fail to meet the requirements, the entire

lot represented must be rejected.

(2) Guided bend test. A root bend test

specimen must be cut from the cylinder

or welded test plate, used for the tensile

test specified in paragraph (n)(1) of this

section. Specimens must be prepared

and tested in accordance with and must

meet the requirements of CGA Pamphlet

C–3.

(3) Alternate guided-bend test. This

test may be used and must be as

required by CGA Pamphlet C–3. The

specimen must be bent until the

elongation at the outer surface, adjacent

to the root of the weld, between the

lightly scribed gage lines-a to b, must be

at least 20 percent, except that this

percentage may be reduced for steels

having a tensile strength in excess of

50,000 pounds per square inch, as

provided in paragraph (m) of this

section.

(o) Rejected cylinders. Reheat

treatment of rejected cylinders is

authorized. Subsequent thereto,

cylinders must pass all prescribed tests

to be acceptable. Repair by welding is

authorized.

(p) Porous filling. (1) Cylinders must

be filled with a porous material in

accordance with the following:

(i) The porous material may not

disintegrate or sag when wet with

solvent or when subjected to normal

service;

(ii) The filling material must be

uniform in quality and free of voids,

except that a well drilled into the filling

material beneath the valve is authorized

if the well is filled with a material of

such type that the functions of the

filling material are not impaired;

(iii) Overall shrinkage of the filling

material is authorized if the total

clearance between the cylinder shell

and filling material, after solvent has

been added, does not exceed 1⁄2 of 1

percent of the respective diameter or

length but not to exceed 1⁄8 inch,

measured diametrically and

longitudinally;

(iv) The clearance may not impair the

functions of the filling material;

(v) The installed filling material must

meet the requirements of CGA Pamphlet

C–12; and

(vi) Porosity of filling material may

not exceed 80 percent except that filling

material with a porosity of up to 92

percent may be used when tested with

satisfactory results in accordance with

CGA Pamphlet C–12.

(2) When the porosity of each cylinder

is not known, a cylinder taken at

random from a lot of 200 or less must

be tested for porosity. If the test cylinder

fails, each cylinder in the lot may be

tested individually and those cylinders

that pass the test are acceptable.

(3) For filling that is molded and

dried before insertion in cylinders,

porosity test may be made on sample

block taken at random from material to

be used.

(4) The porosity of the filling material

must be determined; the amount of

solvent at 70° F for a cylinder:

(i) Having shell volumetric capacity

above 20 pounds water capacity

(nominal) may not exceed the following:

Percent porosity of filler

Maximum

acetone

solvent

percent

shell capacity

by volume

90 to 92 ........................................... 43.4

87 to 90 ........................................... 42.0

83 to 87 ........................................... 40.0

80 to 83 ........................................... 38.6

75 to 80 ........................................... 36.2

70 to 75 ........................................... 33.8

65 to 70 ........................................... 31.4

(ii) Having volumetric capacity of 20

pounds or less water capacity (nominal),

may not exceed the following:

Percent porosity of filler

Maximum

acetone

solvent

percent

shell capacity

by volume

90 to 92 ........................................... 41.8

83 to 90 ........................................... 38.5

80 to 83 ........................................... 37.1

75 to 80 ........................................... 34.8

70 to 75 ........................................... 32.5

65 to 70 ........................................... 30.2

(q) Tare weight. The tare weight is the

combined weight of the cylinder proper,

porous filling, valve, and solvent, but

without removable cap.

(r) Duties of inspector. In addition to

the requirements of § 178.35, the

inspector shall—

(1) Certify chemical analyses of steel

used, signed by manufacturer thereof;

also verify by check analyses, of

samples taken from each heat or from 1

out of each lot of 200 or less plates,

shells, or tubes used.

(2) Verify compliance of cylinder

shells with all shell requirements,

inspect inside before closing in both

ends, verify heat treatment as proper;

obtain all samples for all tests and for

check analyses, witness all tests; verify

threads by gauge, report volumetric

capacity and minimum thickness of

wall noted.

(3) Report percentage of each

specified alloying element in the steel.

Prepare report on manufacture of steel

shells in form prescribed in § 178.35.

Furnish one copy to manufacturer and

three copies to the company that is to

complete the cylinders.

(4) Determine porosity of filling and

tare weights; verify compliance of

marking with prescribed requirements;

obtain necessary copies of steel shell

reports prescribed in paragraph (b) of

this section; and furnish complete test

reports required by this specification to

the person who has completed the

manufacturer of the cylinders and, upon

request, to the purchaser. The test

reports must be retained by the

inspector for fifteen years from the

original test date of the cylinder.

(s) Marking. (1) Tare weight of

cylinder, in pounds and ounces, must

be marked on the cylinder.

(2) Cylinders, not completed, when

delivered must each be marked for

identification of each lot of 200 or less.

(3) Markings must be stamped plainly

and permanently in locations in

accordance with the following:

(i) On shoulders and top heads not

less than 0.087 inch thick; or

(ii) On neck, valve boss, valve

protection sleeve, or similar part

permanently attached to the top end of

cylinder; or

(iii) On a plate of ferrous material

attached to the top of the cylinder or

permanent part thereof; the plate must

be at least 1⁄16 inch thick, and must be

attached by welding, or by brazing at a

temperature of at least 1,100 °F

throughout all edges of the plate.

Sufficient space must be left on the

plate to provide for stamping at least

four (4) retest dates. § 178.61

Specification 4BW welded steel

cylinders with electric-arc welded

longitudinal seam.
25978 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

(a) Type, size and service pressure. A

DOT 4BW cylinder is a welded type

steel cylinder with a longitudinal

electric-arc welded seam, a water

capacity (nominal) not over 1,000

pounds and a service pressure at least

225 and not over 500 pounds per square

inch gauge. Cylinders closed in by

spinning process are not authorized.

(b) Authorized steel. Steel used in the

construction of the cylinder must

conform to the following:

(1) The body of the cylinder must be

constructed of steel conforming to the

limits specified in Table I of Appendix

A to this part.

(2) Material for heads must meet the

requirements of paragraph (a) of this

section or be open hearth, electric or

basic oxygen carbon steel of uniform

quality. Content percent may not exceed

the following: Carbon 0.25, Manganese

0.60, Phosphorus 0.045, Sulfur 0.050.

Heads must be hemispherical or

ellipsoidal in shape with a maximum

ratio of 2.1. If low carbon steel is used,

the thickness of such heads must be

determined by using a maximum wall

stress of 24,000 p.s.i. in the formula

described in paragraph (f)(1) of this

section.

(c) Identification of material. Material

must be identified by any suitable

method.

(d) Manufacture. Cylinders must be

manufactured using equipment and

processes adequate to ensure that each

cylinder produced conforms to the

requirements of this subpart and the

following:

(1) No defect is permitted that is

likely to weaken the finished cylinder

appreciably. A reasonably smooth and

uniform surface is required. Exposed

bottom welds on cylinders over 18

inches long must be protected by

footrings. Minimum thickness of heads

may not be less than 90 percent of the

required thickness of the sidewall.

Heads must be concave to pressure.

(2) Circumferential seams must be by

electric-arc welding. Joints must be butt

with one member offset (joggle butt) or

lap with minimum overlap of at least

four times nominal sheet thickness.

(3) Longitudinal seams in shells must

conform to the following:

(i) Longitudinal electric-arc welded

seams must be of the butt welded type.

Welds must be made by a machine

process including automatic feed and

welding guidance mechanisms.

Longitudinal seams must have complete

joint penetration, and must be free from

undercuts, overlaps or abrupt ridges or

valleys. Misalignment of mating butt

edges may not exceed 1⁄6 of nominal

sheet thickness or 1⁄32 inch whichever is

less. All joints with nominal sheet

thickness up to and including 1⁄8 inch

must be tightly butted. When nominal

sheet thickness is greater than 1⁄8 inch,

the joint must be gapped with maximum

distance equal to one-half the nominal

sheet thickness or 1⁄32 inch whichever is

less. Joint design, preparation and fit-up

must be such that requirements of this

paragraph (d) are satisfied.

(ii) Maximum joint efficiency must be

1.0 when each seam is radiographed

completely. Maximum joint efficiency

must be 0.90 when one cylinder from

each lot of 50 consecutively welded

cylinders is spot radiographed. In

addition, one out of the first five

cylinders welded following a shut down

of welding operations exceeding four

hours must be spot radiographed. Spot

radiographs, when required, must be

made of a finished welded cylinder and

must include the girth weld for 2 inches

in both directions from the intersection

of the longitudinal and girth welds and

include at least 6 inches of the

longitudinal weld. Maximum joint

efficacy of 0.75 must be permissible

without radiography.

(4) Welding procedures and operators

must be qualified in accordance with

CGA Pamphlet C–3.

(e) Welding of attachments. The

attachment to the tops and bottoms only

of cylinders by welding of neckrings,

footrings, handles, bosses, pads and

valve protection rings is authorized

provided that such attachments and the

portion of the container to which they

are attached are made of weldable steel,

the carbon content of which may not

exceed 0.25 percent.

(f) Wall thickness. For outside

diameters over 6 inches the minimum

wall thickness must be 0.078 inch. For

a cylinder with a wall thickness less

than 0.100 inch, the ratio of tangential

length to outside diameter may not

exceed 4 to1 (4:1). In any case the

minimum wall thickness must be such

that the wall stress calculated by the

formula listed in paragraph (f)(4) of this

section may not exceed the lesser value

of any of the following:

(1) The value referenced in paragraph

(b) of this section for the particular

material under consideration.

(2) One-half of the minimum tensile

strength of the material determined as

required in paragraph (m) of this

section.

(3) 35,000 pounds per square inch.

(4) Stress must be calculated by the

following formula:

S=[2P(1.3D2+0.4d2)]/[E(D2¥d2)]

where:

S=wall stress, p.s.i.;

P=service pressure, p.s.i.;

D=outside diameter, inches;

d=inside diameter, inches;

E=joint efficiency of the longitudinal

seam (from paragraph (d) of this

section).

(g) Heat treatment. Each cylinder

must be uniformly and properly heat

treated prior to test by the applicable

method referenced in paragraph (b) of

this section. Heat treatment must be

accomplished after all forming and

welding operations. Heat treatment is

not required after welding or brazing of

weldable low carbon parts to

attachments of similar material which

have been previously welded to the top

or bottom of cylinders and properly heat

treated, provided such subsequent

welding or brazing does not produce a

temperature in excess of 400° F in any

part of the top or bottom material.

(h) Openings in cylinders. Openings

in the cylinder must conform to the

following:

(1) All openings must be in the heads

or bases.

(2) Openings in cylinders must be

provided with adequate fittings, bosses,

or pads, integral with or securely

attached to the cylinder by welding.

(3) Threads must comply with the

following:

(i) Threads must be clean cut and to

gauge.

(ii) Taper threads must be of length

not less than as specified for American

Standard Taper Pipe threads.

(iii) Straight threads, having at least 4

engaged threads, to have tight fit and

calculated shear strength at least 10

times the test pressure of the cylinder;

gaskets required, adequate to prevent

leakage.

(4) Closure of fittings, boss or pads

must be adequate to prevent leakage.

(i) Hydrostatic test. Cylinders must

withstand a hydrostatic test, as follows:

(1) The test must be by water-jacket,

or other suitable method, operated so as

to obtain accurate data. The pressure

gauge must permit readings to an

accuracy of 1 percent. The expansion

gauge must permit readings of total

volumetric expansion to an accuracy

either of 1 percent or 0.1 cubic

centimeter.

(2) Pressure must be maintained for at

least 30 seconds and sufficiently longer

to ensure complete expansion. Any

internal pressure applied after heat

treatment and previous to the official

test may not exceed 90 percent of the

test pressure.

(3) Permanent volumetric expansion

may not exceed 10 percent of the total

volumetric expansion at test pressure.

(4) Cylinders must be tested as

follows:

(i) At least 1 cylinder selected at

random out of each lot of 200 or less
Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations 25979

must be tested as outlined in paragraphs

(i)(1), (i)(2), and (i)(3) of this section to

at least two times service pressure.

(ii) All cylinders not tested as

outlined in paragraph (i)(4)(i) of this

section must be examined under

pressure of at least two times service

pressure and show no defect.

(5) One finished cylinder selected at

random out of each lot of 500 or less

successively produced must be

hydrostatically tested to 4 times service

pressure without bursting.

(j) Physical tests. Cylinders must be

subjected to a physical test as follows:

(1) Specimens must be taken from one

cylinder after heat treatment and chosen

at random from each lot of 200 or less,

as follows:

(i) Body specimen. One specimen

must be taken longitudinally from the

body section at least 90 degrees away

from the weld.

(ii) Head specimen. One specimen

must be taken from either head on a

cylinder when both heads are made of

the same material. However, if the two

heads are made of differing materials, a

specimen must be taken from each head.

(iii) If due to welded attachments on

the top head there is insufficient surface

from which to take a specimen, it may

be taken from a representative head of

the same heat treatment as the test

cylinder.

(2) Specimens must conform to the

following:

(i) A gauge length of 8 inches with a

width not over 11⁄2 inches, a gauge

length of 2 inches with a width not over

11⁄2 inches, or a gauge length at least 24

times thickness with a width not over 6

times thickness is authorized when a

cylinder wall is not over 3⁄16 inch thick.

(ii) The specimen, exclusive of grip

ends, may not be flattened. Grip ends

may be flattened to within 1 inch of

each end of the reduced section.

(iii) When size of the cylinder does

not permit securing straight specimens,

the specimens may be taken in any

location or direction and may be

straightened or flattened cold, by

pressure only, not by blows when

specimens are so taken and prepared,

the inspector’s report must show in

connection with record of physical tests

detailed information in regard to such

specimens.

(iv) Heating of a specimen for any

purpose is not authorized.

(3) The yield strength in tension must

be the stress corresponding to a

permanent strain of 0.2 percent of the

gauge length. The following conditions

apply:

(i) The yield strength must be

determined by either the ‘‘off-set’’

method or the ‘‘extension under load’’

method as prescribed in ASTM

Standard E8.

(ii) In using the ‘‘extension under

load’’ method, the total strain (or

‘‘extension under load’’), corresponding

to the stress at which the 0.2-percent

permanent strain occurs may be

determined with sufficient accuracy by

calculating the elastic extension of the

gauge length under appropriate load and

adding thereto 0.2 percent of the gauge

length. Elastic extension calculations

must be based on an elastic modulus of

30,000,000. In the event of controversy,

the entire stress-strain diagram must be

plotted and the yield strength

determined from the 0.2-percent offset.

(iii) For the purpose of strain

measurement, the initial strain reference

must be set while the specimen is under

a stress of 12,000 pounds per square

inch and the strain indicator reading

being set at the calculated

corresponding strain.

(iv) Cross-head speed of the testing

machine may not exceed 1⁄8 inch per

minute during yield strength

determination.

(k) Elongation. Physical test

specimens must show at least a 40

percent elongation for a 2-inch gauge

length or at least a 20 percent elongation

in other cases. Except that these

elongation percentages may be reduced

numerically by 2 for 2-inch specimens

and by 1 in other cases for each 7,500

pounds per square inch increment of

tensile strength above 50,000 pounds

per square inch to a maximum of four

increments.

(l) Tests of welds. Welds must be

subjected to the following tests:

(1) Tensile test. A specimen must be

cut from one cylinder of each lot of 200

or less. The specimen must be taken

from across the longitudinal seam and

must be prepared and tested in

accordance with and must meet the

requirements of CGA Pamphlet C–3.

(2) Guided bend test. A root test

specimen must be cut from the cylinder

used for the tensile test specified in

paragraph (l)(1) of this section.

Specimens must be taken from across

the longitudinal seam and must be

prepared and tested in accordance with

and must meet the requirements of CGA

Pamphlet C–3.

(3) Alternate guided bend test. This

test may be used and must be as

required by CGA Pamphlet C–3. The

specimen must be bent until the

elongation at the outer surface, adjacent

to the root of the weld, between the

lightly scribed gauge lines a to b, must

be at least 20 percent, except that this

percentage may be reduced for steels

having a tensile strength in excess of

50,000 pounds per square inch, as

provided in paragraph (k) of this

section.

(m) Radiographic examination. Welds

of the cylinders must be subjected to a

radiographic examination as follows:

(1) Radiographic inspection must

conform to the techniques and

acceptability criteria set forth in CGA

Pamphlet C–3. When fluoroscopic

inspection is used, permanent film

records need not be retained.

(2) Should spot radiographic

examination fail to meet the

requirements of paragraph (m)(1) of this

section, two additional welds from the

same lot of 50 cylinders or less must be

examined, and if either of these fail to

meet the requirements, each cylinder

must be examined as previously

outlined; only those passing are

acceptable.

(n) Rejected cylinders. (1) Unless

otherwise stated, if a sample cylinder or

specimen taken from a lot of cylinders

fails the prescribed test, then two

additional specimens must be selected

from the same lot and subjected to the

prescribed test. If either of these fails the

test, then the entire lot must be rejected.

(2) Reheat treatment of rejected

cylinders is authorized. Subsequent

thereto, cylinders must pass all

prescribed tests to be acceptable. Repair

of welded seams by welding is

authorized provided that all defective

metal is cut away and the joint is

rewelded as prescribed for original

welded joints.

(o) Markings. Markings must be

stamped plainly and permanently in

any of the following locations on the

cylinder:

(1) On shoulders and top heads when

they are not less than 0.087-inch thick.

(2) On a metal plate attached to the

top of the cylinder or permanent part

thereof; sufficient space must be left on

the plate to provide for stamping at least

six retest dates; the plate must be at

least 1⁄16-inch thick and must be

attached by welding, or by brazing. The

brazing rod is to melt at a temperature

of 1100°F Welding or brazing must be

along all the edges of the plate.

(3) On the neck, valve boss, valve

protection sleeve, or similar part

permanently attached to the top of the

cylinder.

(4) On the footring permanently

attached to the cylinder, provided the

water capacity of the cylinder does not

exceed 25 pounds.

(p) Inspector’s report. In addition to

the information required by § 178.35,

the inspector’s report must indicate the

type and amount of radiography.
25980 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

§ 178.65 Specification 39 non-reusable

(non-refillable) cylinders.

(a) Type, size, service pressure, and

test pressure. A DOT 39 cylinder is a

seamless, welded, or brazed cylinder

with a service pressure not to exceed 80

percent of the test pressure. Spherical

pressure vessels are authorized and

covered by references to cylinders in

this specification.

(1) Size limitation. Maximum water

capacity may not exceed: (i) 55 pounds

(1,526 cubic inches) for a service

pressure of 500 p.s.i.g. or less, and (ii)

10 pounds (277 cubic inches) for a

service pressure in excess of 500 p.s.i.g.

(2) Test pressure. The minimum test

pressure is the maximum pressure of

contents at 130° F or 180 p.s.i.g.

whichever is greater.

(3) Pressure of contents. The term

‘‘pressure of contents’’ as used in this

specification means the total pressure of

all the materials to be shipped in the

cylinder.

(b) Material; steel or aluminum. The

cylinder must be constructed of either

steel or aluminum conforming to the

following requirements:

(1) Steel. (i) The steel analysis must

conform to the following:

Ladle

analysis

Check

analysis

Carbon, maximum percent ............................ 0.12 0.15

Phosphorus, maximum

percent ....................... .04 .05

Sulfur, maximum percent ............................ .05 .06

(ii) For a cylinder made of seamless

steel tubing with integrally formed ends,

hot drawn, and finished, content

percent for the following may not

exceed: Carbon, 0.55; phosphorous,

0.045; sulfur, 0.050.

(iii) For non-heat treated welded steel

cylinders, adequately killed deep

drawing quality steel is required.

(iv) Longitudinal or helical welded

cylinders are not authorized for service

pressures in excess of 500 p.s.i.g.

(2) Aluminum. Aluminum is not

authorized for service pressures in

excess of 500 p.s.i.g. The analysis of the

aluminum must conform to the

Aluminum Association standard for

alloys 1060, 1100, 1170, 3003, 5052,

5086, 5154, 6061, and 6063 as specified

in its publication entitled ‘‘Aluminum

Standards and Data’’.

(3) Material with seams, cracks,

laminations, or other injurious defects

not permitted.

(4) Material used must be identified

by any suitable method.

(c) Manufacture. (1) General

manufacturing requirements are as

follows:

(i) The surface finish must be uniform

and reasonably smooth.

(ii) Inside surfaces must be clean, dry,

and free of loose particles.

(iii) No defect of any kind is permitted

if it is likely to weaken a finished

cylinder.

(2) Requirements for seams:

(i) Brazing is not authorized on

aluminum cylinders.

(ii) Brazing material must have a

melting point of not lower than 1,000

°F.

(iii) Brazed seams must be assembled

with proper fit to ensure complete

penetration of the brazing material

throughout the brazed joint.

(iv) Minimum width of brazed joints

must be at least four times the thickness

of the shell wall.

(v) Brazed seams must have design

strength equal to or greater than 1.5

times the minimum strength of the shell

wall.

(vi) Welded seams must be properly

aligned and welded by a method that

provides clean, uniform joints with

adequate penetration.

(vii) Welded joints must have a

strength equal to or greater than the

minimum strength of the shell material

in the finished cylinder.

(3) Attachments to the cylinder are

permitted by any means which will not

be detrimental to the integrity of the

cylinder. Welding or brazing of

attachments to the cylinder must be

completed prior to all pressure tests.

(4) Welding procedures and operators

must be qualified in accordance with

CGA Pamphlet C–3.

(d) Wall thickness. The minimum

wall thickness must be such that the

wall stress at test pressure does not

exceed the yield strength of the material

of the finished cylinder wall.

Calculations must be made by the

following formulas:

(1) Calculation of the stress for

cylinders must be made by the

following formula:

S=[P(1.3D2+0.4d2)]/(D2¥d2)

Where:

S=Wall stress, in p.s.i.;

P=Test pressure;

D=Outside diameter, in inches;

d=Inside diameter, in inches.

(2) Calculation of the stress for

spheres must be made by the following

formula:

S=PD/4t

Where:

S=Wall stress, in p.s.i.;

P=Test pressure;

D=Outside diameter, in inches;

t=Minimum wall thickness, in inches.

(e) Openings and attachments.

Openings and attachments must

conform to the following:

(1) Openings and attachments are

permitted on heads only.

(2) All openings and their

reinforcements must be within an

imaginary circle, concentric to the axis

of the cylinder. The diameter of the

circle may not exceed 80 percent of the

outside diameter of the cylinder. The

plane of the circle must be parallel to

the plane of a circumferential weld and

normal to the long axis of the cylinder.

(3) Unless a head has adequate

thickness, each opening must be

reinforced by a securely attached fitting,

boss, pad, collar, or other suitable

means.

(4) Material used for welded openings

and attachments must be of weldable

quality and compatible with the

material of the cylinder.

(f) Pressure tests. (1) Each cylinder

must be tested at an internal pressure of

at least the test pressure and must be

held at that pressure for at least 30

seconds.

(i) The leakage test must be conducted

by submersion under water or by some

other method that will be equally

sensitive.

(ii) If the cylinder leaks, evidences

visible distortion, or any other defect,

while under test, it must be rejected (see

paragraph (h) of this section).

(2) One cylinder taken from the

beginning of each lot, and one from each

1,000 or less successively produced

within the lot thereafter, must be

hydrostatically tested to destruction.

The entire lot must be rejected (see

paragraph (h) of this section) if:

(i) A failure occurs at a gage pressure

less than 2.0 times the test pressure;

(ii) A failure initiates in a braze or a

weld or the heat affected zone thereof;

(iii) A failure is other than in the

sidewall of a cylinder longitudinal with

its long axis; or

(iv) In a sphere, a failure occurs in any

opening, reinforcement, or at a point of

attachment.

(3) A ‘‘lot’’ is defined as the quantity

of cylinders successively produced per

production shift (not exceeding 10

hours) having identical size, design,

construction, material, heat treatment,

finish, and quality.

(g) Flattening test. One cylinder must

be taken from the beginning of

production of each lot (as defined in

paragraph (f)(3) of this section) and

subjected to a flattening test as follows:

(1) The flattening test must be made

on a cylinder that has been tested at test

pressure.
Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations 25981

(2) A ring taken from a cylinder may

be flattened as an alternative to a test on

a complete cylinder. The test ring may

not include the heat affected zone or

any weld. However, for a sphere, the

test ring may include the

circumferential weld if it is located at a

45 degree angle to the ring, +/¥5

degrees.

(3) The flattening must be between 60

degrees included-angle, wedge shaped

knife edges, rounded to a 0.5 inch

radius.

(4) Cylinders and test rings may not

crack when flattened so that their outer

surfaces are not more than six times

wall thickness apart when made of steel

or not more than ten times wall

thickness apart when made of

aluminum.

(5) If any cylinder or ring cracks when

subjected to the specified flattening test,

the lot of cylinders represented by the

test must be rejected (see paragraph (h)

of this section).

(h) Rejected cylinders. Rejected

cylinders must conform to the following

requirements:

(1) If the cause for rejection of a lot

is determinable, and if by test or

inspection defective cylinders are

eliminated from the lot, the remaining

cylinders must be qualified as a new lot

under paragraphs (f) and (g) of this

section.

(2) Repairs to welds are permitted.

Following repair, a cylinder must pass

the pressure test specified in paragraph

(f) of this section.

(3) If a cylinder made from seamless

steel tubing fails the flattening test

described in paragraph (g) of this

section, suitable uniform heat treatment

must be used on each cylinder in the

lot. All prescribed tests must be

performed subsequent to this heat

treatment.

(i) Markings. (1) The markings

required by this section must be durable

and waterproof. The requirements of

§ 173.24(c)(1) (ii) and (iv) of this

subchapter and § 178.35(h) do not apply

to this section.

(2) Required markings are as follows:

(i) DOT–39.

(ii) NRC.

(iii) The service pressure.

(iv) The test pressure.

(v) The registration number (M****)

of the manufacturer.

(vi) The lot number.

(vii) The date of manufacture if the lot

number does not establish the date of

manufacture.

(viii) With one of the following

statements:

(A) For cylinders manufactured prior

to October 1, 1996: ‘‘Federal law forbids

transportation if refilled-penalty up to

$25,000 fine and 5 years imprisonment

(49 U.S.C. 1809)’’ or ‘‘Federal law

forbids transportation if refilled-penalty

up to $500,000 fine and 5 years

imprisonment (49 U.S.C. 5124).’’

(B) For cylinders manufactured on or

after October 1, 1996: ‘‘Federal law

forbids transportation if refilled-penalty

up to $500,000 fine and 5 years

imprisonment (49 U.S.C. 5124).’’

(3) The markings required by

paragraphs (i)(2)(i) through (i)(2)(v) of

this section must be in numbers and

letters at least 1⁄8 inch high and

displayed sequentially. For example:

DOT–39 NRC 250/500 M1001.

(4) No person may mark any cylinder

with the specification identification

‘‘DOT–39’’ unless it was manufactured

in compliance with the requirements of

this section and its manufacturer has a

registration number (M****) from the

Associate Administrator.

§ 178.68 Specification 4E welded

aluminum cylinders.

(a) Type, size and service pressure. A

DOT 4E cylinder is a welded aluminum

cylinder with a water capacity

(nominal) of not over 1,000 pounds and

a service pressure of at least 225 to not

over 500 pounds per square inch. The

cylinder must be constructed of not

more than two seamless drawn shells

with no more than one circumferential

weld. The circumferential weld may not

be closer to the point of tangency of the

cylindrical portion with the shoulder

than 20 times the cylinder wall

thickness. Cylinders or shells closed in

by spinning process and cylinders with

longitudinal seams are not authorized.

(b) Authorized material. The cylinder

must be constructed of aluminum of

uniform quality. The following chemical

analyses are authorized:

TABLE 1.—AUTHORIZED MATERIALS

Designation

Chemical analysis—

limits in percent

5154 1

Iron plus silicon ......... 0.45 maximum.

Copper ...................... 0.10 maximum.

Manganese ............... 0.10 maximum.

Magnesium ................ 3.10/3.90.

Chromium .................. 0.15/0.35.

Zinc ........................... 0.20 maximum.

Titanium .................... 0.20 maximum.

Others, each ............. 0.05 maximum.

Others, total .............. 0.15 maximum.

Aluminum .................. remainder.

1Analysis must regularly be made only for

the elements specifically mentioned in this

table. If, however, the presence of other elements is indicated in the course of routine

analysis, further analysis should be made to

determine conformance with the limits specified for other elements.

(c) Identification. Material must be

identified by any suitable method that

will identify the alloy and

manufacturer’s lot number.

(d) Manufacture. Cylinders must be

manufactured using equipment and

processes adequate to ensure that each

cylinder produced conforms to the

requirements of this subpart. No defect

is permitted that is likely to weaken the

finished cylinder appreciably. A

reasonably smooth and uniform surface

finish is required. All welding must be

by the gas shielded arc process.

(e) Welding. The attachment to the

tops and bottoms only of cylinders by

welding of neckrings or flanges,

footrings, handles, bosses and pads and

valve protection rings is authorized.

However, such attachments and the

portion of the cylinder to which it is

attached must be made of weldable

aluminum alloys.

(f) Wall thickness. The wall thickness

of the cylinder must conform to the

following:

(1) The minimum wall thickness of

the cylinder must be 0.140 inch. In any

case, the minimum wall thickness must

be such that calculated wall stress at

twice service pressure may not exceed

the lesser value of either of the

following:

(i) 20,000 pounds per square inch.

(ii) One-half of the minimum tensile

strength of the material as required in

paragraph (m) of this section.

(2) Calculation must be made by the

following formula:

S=[P(1.3D2+0.4d2)]/(D2¥d2)

Where:

S=wall stress in pounds per square inch;

P=minimum test pressure prescribed for

water jacket test;

D=outside diameter in inches;

d=inside diameter in inches.

(3) Minimum thickness of heads and

bottoms may not be less than the

minimum required thickness of the side

wall.

(g) Opening in cylinder. Openings in

cylinders must conform to the

following:

(1) All openings must be in the heads

or bases.

(2) Each opening in cylinders, except

those for safety devices, must be

provided with a fitting, boss, or pad,

securely attached to cylinder by welding

by inert gas shielded arc process or by

threads. If threads are used, they must

comply with the following:

(i) Threads must be clean-cut, even,

without checks and cut to gauge.

(ii) Taper threads to be of length not

less than as specified for American

Standard taper pipe threads.

(iii) Straight threads, having at least 4

engaged threads, to have tight fit and
25982 Federal Register / Vol. 61, No. 101 / Thursday, May 23, 1996 / Rules and Regulations

calculated shear strength at least 10

times the test pressure of the cylinder;

gaskets required, adequate to prevent

leakage.

(3) Closure of a fitting, boss, or pad

must be adequate to prevent leakage.

(h) Hydrostatic test. Each cylinder

must successfully withstand a

hydrostatic test, as follows:

(1) The test must be by water jacket,

or other suitable method, operated so as

to obtain accurate data. The pressure

gauge must permit reading to an

accuracy of 1 percent. The expansion

gauge must permit a reading of the total

expansion to an accuracy either of 1

percent or 0.1 cubic centimeter.

(2) Pressure of 2 times service

pressure must be maintained for at least

30 seconds and sufficiently longer to

insure complete expansion. Any

internal pressure applied previous to

the official test may not exceed 90

percent of the test pressure. If, due to

failure of the test apparatus, the test

pressure cannot be maintained, the test

may be repeated at a pressure increased

by 10 percent over the pressure

otherwise specified.

(3) Permanent volumetric expansion

may not exceed 12 percent of total

volumetric expansion at test pressure.

(4) Cylinders having a calculated wall

stress of 18,000 pounds per square inch

or less at test pressure may be tested as

follows:

(i) At least one cylinder selected at

random out of each lot of 200 or less

must be tested in accordance with

paragraphs (h)(1), (h)(2), and (h)(3) of

this section.

(ii) All cylinders not tested as

provided in paragraph (h)(4)(i) of this

section must be examined under

pressure of at least 2 times service

pressure and show no defect.

(5) One finished cylinder selected at

random out of each lot of 1,000 or less

must be hydrostatically tested to 4 times

the service pressure without bursting.

Inability to meet this requirement must

result in rejection of the lot.

(i) Flattening test. After hydrostatic

testing, a flattening test is required on

one section of a cylinder, taken at

random out of each lot of 200 or less as

follows:

(1) If the weld is not at midlength of

the cylinder, the test section must be no

less in width than 30 times the cylinder

wall thickness. The weld must be in the

center of the section. Weld

reinforcement must be removed by

machining or grinding so that the weld

is flush with the exterior of the parent

metal. There must be no evidence of

cracking in the sample when it is

flattened between flat plates to no more

than 6 times the wall thickness.

(2) If the weld is at midlength of the

cylinder, the test may be made as

specified in paragraph (i)(1)(i) of this

section or must be made between wedge

shaped knife edges (60° angle) rounded

to a 1⁄2 inch radius. There must be no

evidence of cracking in the sample

when it is flattened to no more than 6

times the wall thickness.

(j) Physical test. A physical test must

be conducted to determine yield

strength, tensile strength, elongation,

and reduction of area of material as

follows:

(1) The test is required on 2

specimens cut from one cylinder or part

thereof taken at random out of each lot

of 200 or less.

(2) Specimens must conform to the

following:

(i) A gauge length of 8 inches with a

width not over 11⁄2 inches, a gauge

length of 2 inches with a width not over

11⁄2 inches.

(ii) The specimen, exclusive of grip

ends, may not be flattened. Grip ends

may be flattened to within 1 inch of

each end of the reduced section.

(iii) When size of cylinder does not

permit securing straight specimens, the

specimens may be taken in any location

or direction and may be straightened or

flattened cold, by pressure only, not by

blows; when specimens are so taken and

prepared, the inspector’s report must

show in connection with record of

physical test detailed information in

regard to such specimens.

(iv) Heating of a specimen for any

purpose is not authorized.

(3) The yield strength in tension must

be the stress corresponding to a

permanent strain of 0.2 percent of the

gauge length. The following conditions

apply:

(i) The yield strength must be

determined by the ‘‘offset’’ method as

prescribed in ASTM Standard E8.

(ii) Cross-head speed of the testing

machine may not exceed 1⁄8 inch per

minute during yield strength

determination.

(k) Acceptable results for physical

tests. An acceptable result of the

physical test requires an elongation to at

least 7 percent and yield strength not

over 80 percent of tensile strength.

(l) Weld tests. Welds of the cylinder

are required to successfully pass the

following tests:

(1) Reduced section tensile test. A

specimen must be cut from the cylinder

used for the physical tests specified in

paragraph (j) of this section. The

specimen must be taken from across the

seam, edges must be parallel for a

distance of approximately 2 inches on

either side of the weld. The specimen

must be fractured in tension. The

apparent breaking stress calculated on

the minimum wall thickness must be at

least equal to 2 times the stress

calculated under paragraph (f)(2) of this

section, and in addition must have an

actual breaking stress of at least 30,000

pounds per square inch. Should this

specimen fail to meet the requirements,

specimens may be taken from 2

additional cylinders from the same lot

and tested. If either of the latter

specimens fails to meet requirements,

the entire lot represented must be

rejected.

(2) Guided bend test. A bend test

specimen must be cut from the cylinder

used for the physical tests specified in

paragraph (j) of this section. Specimen

must be taken across the seam, must be

11⁄2 inches wide, edges must be parallel

and rounded with a file, and back-up

strip, if used, must be removed by

machining. The specimen must be bent

to refusal in the guided bend test jig

illustrated in paragraph 6.10 of CGA

Pamphlet C–3. The root of the weld

(inside surface of the cylinder) must be

located away from the ram of the jig. No

specimen must show a crack or other

open defect exceeding 1⁄8 inch in any

direction upon completion of the test.

Should this specimen fail to meet the

requirements, specimens may be taken

from each of 2 additional cylinders from

the same lot and tested. If either of the

latter specimens fail to meet

requirements, the entire lot represented

must be rejected.

(m) Rejected cylinders. Repair of

welded seams is authorized. Acceptable

cylinders must pass all prescribed tests.

(n) Inspector’s report. In addition to

the information required by § 178.35,

the record of chemical analyses must

also include applicable information on

iron, titanium, zinc, and magnesium

used in the construction of the cylinder.

Issued in Washington, DC on May 8, 1996,

under authority delegated in 49 CFR Part 1.

Rose McMurray,

Acting Deputy Administrator, Research and

Special Programs Administration.

[FR Doc. 96–12029 Filed 5–22–96; 8:45 am]

BILLING CODE 4910–60–P