What Every Member of the 

Trade Community Should Know About: 

Distinguishing Bolts 

from Screws 

AN INFORMED COMPLIANCE PUBLICATION 

JULY 2012 
Distinguishing Bolts from Screws 

July 2012 

NOTICE:

This publication is intended to provide guidance and information to the trade community. 

It reflects the position on or interpretation of the applicable laws or regulations by U.S. 

Customs and Border Protection (CBP) as of the date of publication, which is shown on 

the front cover. It does not in any way replace or supersede those laws or regulations. 

Only the latest official version of the laws or regulations is authoritative. 

Publication History 

First Published: May 1997 

Revised May 2000 

Revised October 2003 

Revised January 2004 

Reviewed With No Changes May 2005 

Reviewed With No Changes March 2006 

Reviewed With No Changes January 2008 

Reviewed With No Changes March 2009 

Revised March 2010 

Reviewed With No Changes February 2011 

Revised July 2012 

PRINTING NOTE: 

This publication was designed for electronic distribution via the CBP website 

(http://www.cbp.gov) and is being distributed in a variety of formats. It was originally set 

up in Microsoft Word 2003®. Pagination and margins in downloaded versions may vary 

depending upon which word processor or printer you use. If you wish to maintain the 

original settings, you may wish to download the .pdf version, which can then be printed 

using the freely available Adobe Acrobat Reader®. 

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PREFACE 

On December 8, 1993, Title VI of the North American Free Trade Agreement Implementation 

Act (Pub. L. 103-182, 107 Stat. 2057), also known as the Customs Modernization or “Mod” Act, 

became effective. These provisions amended many sections of the Tariff Act of 1930 and 

related laws. 

Two new concepts that emerge from the Mod Act are “informed compliance” and “shared 

responsibility,” which are premised on the idea that in order to maximize voluntary compliance 

with laws and regulations of U.S. Customs and Border Protection, the trade community needs to 

be clearly and completely informed of its legal obligations. Accordingly, the Mod Act imposes a 

greater obligation on CBP to provide the public with improved information concerning the trade 

community's rights and responsibilities under customs regulations and related laws. In addition, 

both the trade and U.S. Customs and Border Protection share responsibility for carrying out 

these requirements. For example, under Section 484 of the Tariff Act, as amended (19 U.S.C. 

1484), the importer of record is responsible for using reasonable care to enter, classify and 

determine the value of imported merchandise and to provide any other information necessary to 

enable U.S. Customs and Border Protection to properly assess duties, collect accurate 

statistics, and determine whether other applicable legal requirements, if any, have been met. 

CBP is then responsible for fixing the final classification and value of the merchandise. An 

importer of record’s failure to exercise reasonable care could delay release of the merchandise 

and, in some cases, could result in the imposition of penalties. 

Regulations and Rulings (RR) of the Office of International Trade has been given a major role in 

meeting the informed compliance responsibilities of U.S. Customs and Border Protection. In 

order to provide information to the public, CBP has issued a series of informed compliance 

publications on new or revised requirements, regulations or procedures, and a variety of 

classification and valuation issues. 

This publication, prepared by the National Commodity Specialist Division of Regulations and 

Rulings is entitled "Distinguishing Bolts from Screws.” It provides guidance regarding the 

classification of these items. We sincerely hope that this material, together with seminars and 

increased access to rulings of U.S. Customs and Border Protection, will help the trade 

community to improve voluntary compliance with customs laws and to understand the relevant 

administrative processes. 

The material in this publication is provided for general information purposes only. Because 

many complicated factors can be involved in customs issues, an importer may wish to obtain a 

ruling under Regulations of U.S. Customs and Border Protection, 19 C.F.R. Part 177, or to 

obtain advice from an expert who specializes in customs matters, for example, a licensed 

customs broker, attorney or consultant. 

Comments and suggestions are welcomed and should be addressed to U.S. Customs and 

Border Protection, Office of International Trade, Executive Director, Regulations and Rulings, 

799 9th Street N.W. 7th floor, Washington, D.C. 20229-1177. 

Sandra L. Bell 

Executive Director, Regulations and Rulings 

Office of International Trade 

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I. INTRODUCTION.......................................................................................7

II. SPECIFICATIONS...................................................................................8

1. SCOPE..................................................................................................................... 8

2. DEFINITIONS........................................................................................................... 8

3. EXPLANATORY DATA ............................................................................................ 8

4. PROCEDURE .......................................................................................................... 9

5. PRIMARY CRITERIA ............................................................................................... 9

6. SUPPLEMENTARY CRITERIA.............................................................................. 11

III. INVOICING ...........................................................................................16

ADDITIONAL INFORMATION...................................................................18

The Internet................................................................................................................ 18

Customs Regulations ................................................................................................. 18

Customs Bulletin ........................................................................................................ 18

Importing into the United States ................................................................................. 19

Informed Compliance Publications............................................................................. 19

Value Publications...................................................................................................... 20

“Your Comments are Important”................................................................................. 21

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I. INTRODUCTION 

STEEL SCREWS AND BOLTS are classified in Chapter 73, Harmonized Tariff 

Schedule of the United States (HTSUS) under heading 7318. The tariff has separate 

provisions for the different types of screws and bolts, and separate provisions for 

threaded and non-threaded fasteners. The tariff pages covering the various types of 

steel screws and bolts can be found by checking the latest version of the HTSUS at 

www.usitc.gov. 

U.S. Customs and Border Protection (CBP) uses the “Specification for Identification of 

Bolts and Screws,” ANSI - ASME B18.2.1 1981 (the “Specification”) to distinguish bolts 

from screws.1 In Rocknel Fastener, Inc. v. United States, 24 C.I.T. 900, 118 F.Supp. 2d 

1238 (Ct. Int’l. Trade 2000), the Court of International Trade (CIT) sanctioned the use of 

the Specification for this purpose, stating that it provides a well-recognized, 

comprehensive basis for the common and commercial meaning of bolt and screw as 

understood by the fastener industry in the United States. See Id., at 906 and 913, 118 

F.Supp. 2d at 1243 and 1249. The standard is full of industry jargon, so to make it 

easier to use, we have combined it here with illustrations and glossary terms from

Fastener Standards 6th Edition, Industrial Fasteners Institute, Cleveland, Ohio 44114, 

1988. (This informed compliance publication is not meant to substitute for the book. 

Rather, it is intended to acquaint you with some of the book's contents.) 

Here are a couple of helpful hints for applying the Specification. The Specification

includes both primary and supplementary criteria. The primary criteria are easy enough 

to understand, but in applying the supplementary criteria a few things should be kept in 

mind. 

FIRST, the supplementary criteria help you distinguish coarser (or loose tolerance) bolts 

from finer (or close tolerance) screws. When the supplementary criteria are applied, the 

coarser product usually turns out to be a bolt, the finer product usually turns out to be a 

screw. “Coarse” and “fine” are looked at from nine different aspects of the screw. In 

some industries, e.g., automotive, aircraft, and aerospace, the tolerances are almost 

always close, so it’s not often necessary to spend a lot of time on supplementary criteria 

when the fastener is from one of these industries; that is, if it doesn't meet the primary 

criteria (and of course, if it doesn't conform to a fastener industry standard for a bolt), 

then it probably is a screw. 

SECOND, when applying the supplementary criteria try to avoid applying the criteria to 

a sample fastener. It is more effective to compare drawings to drawings. That is, if you 

can get a hold of the specification drawing to which the fastener was made, take that 

drawing and compare it to the drawing of an industry standard fastener. Compare the 

 

1

 CBP has previously found that international standards are not necessarily applicable. See HQ H095040, dated 

November 1, 2010; HQ 959280, dated December 19, 2000 (both rejecting the use of International Organization 

for Standardization (ISO) standards in distinguishing bolts from screws). Furthermore, the CIT stated that the 

Specification is equally applicable to metric fasteners. Rocknel, at 911, FN11, 118 F.Supp. 2d at 1247. 

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specification to an industry standard in order to see if a given tolerance is fine like a 

screw, or coarse like a bolt. 

FINALLY, keep in mind that all of these rules are subordinate to Customs rulings and 

court decisions. 

II. SPECIFICATIONS 

The following is reproduced from Specification for Identification of Bolts and Screws, 

ANSI-ASME B18.2.1 1981, with illustrations from Fastener Standards, 6th Edition, 

Industrial Fasteners Institute, Cleveland, Ohio. This information has been reprinted 

from ASME B18 Series by permission of The American Society of Mechanical 

Engineers. All rights reserved. 

1. SCOPE 

This specification establishes a recommended procedure for determining the identity of 

an externally threaded fastener as a bolt or as a screw. 

2. DEFINITIONS 

2.1 Bolt 

A bolt is an externally threaded fastener designed for insertion through the holes 

in assembled parts, and is normally intended to be tightened or released by 

torquing a nut. 

2.2 Screw 

A screw is an externally threaded fastener capable of being inserted into holes in 

assembled parts, of mating with a preformed internal thread or forming its own 

thread, and of being tightened or released by torquing the head. 

3. EXPLANATORY DATA 

A bolt is designed for assembly with a nut. A screw has features in its design which 

makes it capable of being used in a tapped or other preformed hole in the work. 

Because of basic design, it is possible to use certain types of screws in combination 

with a nut. Any externally threaded fastener which has a majority of the design 

characteristics which assist its proper use in a tapped or other preformed hole is a 

screw, regardless of how it is used in its service application. 

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4. PROCEDURE 

To identify an externally threaded fastener as a bolt or as a screw, two sets of criteria - 

Primary and Supplementary - shall be applied. The Primary Criteria (5.1 thru 5.4) shall 

be applied first. Any fastener which satisfies one of the Primary Criteria shall be 

identified accordingly, and no further examination need be made. The Supplementary 

Criteria (6.1 through 6.9, and not listed in order of importance or priority of application) 

shall be applied to a fastener which does not satisfy completely any one of the Primary 

Criteria. The Supplementary Criteria detail the principal features in the design of an 

externally threaded fastener which contribute to its proper use as a screw. A fastener 

having a majority of these characteristics shall be identified as a screw. 

 

5. PRIMARY CRITERIA 

5.1 An externally threaded fastener, which because of head design or other 

feature, is prevented from being turned during assembly, and which can be 

tightened or released only by torquing a nut, is a bolt. (Example: round head 

bolts, track bolts, plow bolts). 

EXAMPLES: 

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5.2 An externally threaded fastener, which has a thread form which prohibits 

assembly with a nut having a straight thread of multiple pitch length, is a screw. 

(Example: wood screws, tapping screws). 

EXAMPLES: 

5.3 An externally threaded fastener, which must be assembled with a nut to 

perform its intended service, is a bolt. (Example: heavy hex structural bolt). 

 EXAMPLE

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5.4 An externally threaded fastener, which must be torqued by its head into a 

tapped or other preformed hole to perform its intended service is a screw. 

(Example square head set screw). 

EXAMPLE: 

6. SUPPLEMENTARY CRITERIA 

6.1 Under Head Fillet 

A screw should have a controlled fillet at the junction of the head with the body. 

Because of the severe combined torsion and tension stresses at this junction 

when torquing the head, the minimum limits of the fillet radius should be 

specified. Because the screw must be capable of being turned through a 

minimum clearance hole and into an immovable tapped hole, the maximum limits 

of the fillet radius should be specified to assure solid seating of the head, and to 

prevent interference at the top of the hole with the junction of head to body. 

EXAMPLE: 

Underhead Fillet. An underhead fillet is the concave junction at the head and the 

shank intersection of a headed fastener. 

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6.2 Bearing Surface 

The under head bearing surface of a screw should be smooth and flat to 

minimize frictional resistance during tightening, to prevent scoring of the surface 

against which the head is turned, and to produce uniform clamping loads. 

EXAMPLE: 

Bearing Surface. The bearing surface is the supporting or locating surface of a 

fastener with respect to the part which it fastens (mates). The loading of a 

fastener is usually through the bearing surface. 

6.3 Head Angularity 

The angularity (squareness) of the underhead bearing surface with the shank of 

a screw should be controlled to minimize eccentric loading in the screw or 

assembled parts, and to assure complete seating and uniform underhead 

bearing pressure. 

EXAMPLE: 

Angularity. Angularity is the angle between the axes of two surfaces of a 

fastener. 

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6.4 Body 

The body of a screw should be closely controlled in accuracy of size and 

roundness. To fit effectively through a minimum clearance hole, the body 

diameter must have close tolerances, preferably unilateral on the minus side. 

EXAMPLE: 

Body. The body of a threaded fastener is the unthreaded portion of the shank. 

6.5 Shank Straightness 

The shank of a screw should be particularly straight to permit ready engagement 

with the internal thread, to prevent eccentric loading in the fastener or in the 

assembled parts, and to minimize interference with the walls of a minimum 

clearance hole. 

EXAMPLE: 

Bow or Camber. Bow or camber is the amount that a side of a surface of a 

fastener deviates from being straight. 

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6.6 Thread Concentricity 

The threads of a screw should be concentric with the body axis within close limits 

to permit assembly into a tapped hole (which usually has a length of thread 

engagement longer than a nut) without binding of the body against the walls of a 

minimum clearance hole. 

EXAMPLE:

 

6.7 Thread length 

The length of thread on a screw must be sufficient to develop the full strength of 

the fastener in tapped holes in various materials. 

DEFINITION:

“Length of complete thread” is defined in Fastener Standards 6th Edition 

as: the axial length of a thread section having full form at both crest and 

root but also including a maximum of two pitches at the start of the thread 

which may have a chamfer or incomplete crests. 

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6.8 Point 

A screw should have a chamfered, or other specially prepared point at its end to 

facilitate entry into the hole and easy start with the internal thread, which may be 

distant from the top of the hole. The point also protects the first thread, which, if 

damaged, may gall or scar the internal thread throughout its entire length. 

EXAMPLE: 

Point. The point of a fastener is the configuration of the end of the shank of a 

headed fastener or of each end of a headless fastener. 

6.9 Length 

The length of a screw should be closely toleranced with variance preferably 

unilateral on the minus side to prevent bottoming of the fastener in a tapped hole. 

EXAMPLE: 

Length. The length of a headed fastener is the distance from the intersection of 

the largest diameter of the head with the bearing surface to the extreme point, 

measured in a line parallel to the axis of the fastener. Exceptions: The length of a 

shoulder screw and a socket head shoulder screw is the length of the shoulder. 

The length of a headless fastener is the distance from one extreme point to the 

other, measured in a line parallel to the axis of the fastener. 

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III. INVOICING 

The accuracy of the information contained on invoices is an essential element of the 

structure of the many new and creative programs Customs has undertaken. These 

programs, including, but not limited to automated entry processing, may only provide 

their benefits to the trade community as a whole if the data gathered are correct and 

complete. This concern for invoice accuracy is not new, but as we progress in 

automation, accuracy becomes indispensable. 

Section 141.86 of the Customs Regulations concerns invoicing requirements. 

Subparagraph (a)(3) of the section specifically requires invoices have the following 

information: 

“A detailed description of the merchandise, including the name by which 

each item is known, the grade or quality, and the marks, numbers and 

symbols under which sold by the seller or manufacturer to the trade in the 

country of exportation, together with the marks and numbers of the 

packages in which the merchandise is packed.” 

A “detailed description” is one which enables an import specialist to properly fix the 

classification of imported merchandise. Accordingly, the invoice description must 

indicate any information which has a direct bearing on the proper classification of the 

imported item and it is incumbent upon the importer of record to ensure that the detailed 

description is present on each invoice. 

Importers do not have to provide information that is not necessary to classify a specific 

item. However, they are responsible for giving U.S. Customs and Border Protection the 

information that is needed. 

Invoice guidelines for the importation of bolts and screws should include the following: 

Industry Standards:

List all industry standards to which the fastener is made to conform. 

Description:

If the industry standard includes a prescribed method of designation, use that 

method. In all cases, include: all dimensions, number of threads per inch, product 

name, head type, point type and component material. 

Component Material:

State the name of the material (which predominates by weight), e.g., steel, 

stainless steel, nickel, titanium, copper, etc. For fasteners of high nickel alloy; 

state percentage by weight of: iron, nickel and chromium. 

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Grade:

State the fastener grade, and identify the grading system. 

IV. FURTHER FASTENER CLASSIFICATION GUIDANCE 

An Informed Compliance Publication Fasteners of Heading 7318 has been written to 

provide further guidance to aid in the classification of bolts and screws. 

 

 

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ADDITIONAL INFORMATION 

The Internet 

The home page of U.S. Customs and Border Protection on the Internet’s World Wide 

Web, provides the trade community with current, relevant information regarding CBP 

operations and items of special interest. The site posts information -- which includes 

proposed regulations, news releases, publications and notices, etc. -- that can be 

searched, read on-line, printed or downloaded to your personal computer. The web site 

was established as a trade-friendly mechanism to assist the importing and exporting 

community. The web site also links to the home pages of many other agencies whose 

importing or exporting regulations that U.S. Customs and Border Protection helps to 

enforce. The web site also contains a wealth of information of interest to a broader 

public than the trade community. For instance, the “Know Before You Go” publication 

and traveler awareness campaign is designed to help educate international travelers. 

 

The web address of U.S. Customs and Border Protection is http://www.cbp.gov

Customs Regulations 

The current edition of Customs and Border Protection Regulations of the United States 

is a loose-leaf, subscription publication available from the Superintendent of 

Documents, U.S. Government Printing Office, Washington, DC 20402; telephone (202) 

512-1800. A bound edition of Title 19, Code of Federal Regulations is also available for 

sale from the same address. All proposed and final regulations are published in the 

Federal Register, which is published daily by the Office of the Federal Register, National 

Archives and Records Administration, and distributed by the Superintendent of 

Documents. Information about on-line access to the Federal Register may be obtained 

by calling (202) 512-1530 between 7 a.m. and 5 p.m. Eastern time. These notices are 

also published in the weekly Customs Bulletin described below. 

Customs Bulletin 

The Customs Bulletin and Decisions (“Customs Bulletin”) is a weekly publication that 

contains decisions, rulings, regulatory proposals, notices and other information of 

interest to the trade community. It also contains decisions issued by the U.S. Court of 

International Trade, as well as customs-related decisions of the U.S. Court of Appeals 

for the Federal Circuit. Each year, the Government Printing Office publishes bound 

volumes of the Customs Bulletin. Subscriptions may be purchased from the 

Superintendent of Documents at the address and phone number listed above. 

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Importing into the United States 

This publication provides an overview of the importing process and contains general 

information about import requirements. The current edition of Importing Into the United 

States contains much new and revised material brought about pursuant to the Customs 

Modernization Act (“Mod Act”). The Mod Act has fundamentally altered the relationship 

between importers and U.S. Customs and Border Protection by shifting to the importer 

the legal responsibility for declaring the value, classification, and rate of duty applicable 

to entered merchandise. 

The current edition contains a section entitled "Informed Compliance." A key component 

of informed compliance is the shared responsibility between U.S. Customs and Border 

Protection and the import community, wherein CBP communicates its requirements to 

the importer, and the importer, in turn, uses reasonable care to assure that CBP is 

provided accurate and timely data pertaining to his or her importation. 

Single copies may be obtained from local offices of U.S. Customs and Border 

Protection, or from the Office of Public Affairs, U.S. Customs and Border Protection, 

1300 Pennsylvania Avenue NW, Washington, DC 20229. An on-line version is 

available at the CBP web site. Importing into the United States is also available for 

sale, in single copies or bulk orders, from the Superintendent of Documents by calling 

(202) 512-1800, or by mail from the Superintendent of Documents, U.S. Government 

Printing Office, P.O. Box 979050, St. Louis, MO 63197-9000. 

Informed Compliance Publications 

U.S. Customs and Border Protection has prepared a number of Informed Compliance 

publications in the “What Every Member of the Trade Community Should Know 

About:...” series. Check the Internet web site http://www.cbp.gov for current 

publications. 

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Value Publications 

Customs Valuation under the Trade Agreements Act of 1979 is a 96-page book 

containing a detailed narrative description of the customs valuation system, the customs 

valuation title of the Trade Agreements Act (§402 of the Tariff Act of 1930, as amended 

by the Trade Agreements Act of 1979 (19 U.S.C. §1401a)), the Statement of 

Administrative Action which was sent to the U.S. Congress in conjunction with the TAA, 

regulations (19 C.F.R. §§152.000-152.108) implementing the valuation system (a few 

sections of the regulations have been amended subsequent to the publication of the 

book) and questions and answers concerning the valuation system. 

Customs Valuation Encyclopedia (with updates) is comprised of relevant statutory 

provisions, CBP Regulations implementing the statute, portions of the Customs 

Valuation Code, judicial precedent, and administrative rulings involving application of 

valuation law. A copy may be purchased for a nominal charge from the Superintendent 

of Documents, Government Printing Office, P.O. Box 371954, Pittsburgh, PA 15250-

7054. This publication is also available on the Internet web site of U.S. Customs and 

Border Protection. 

The information provided in this publication is for general information 

purposes only. Recognizing that many complicated factors may be 

involved in customs issues, an importer may wish to obtain a ruling under 

CBP Regulations, 19 C.F.R. Part 177, or obtain advice from an expert 

(such as a licensed Customs Broker, attorney or consultant) who 

specializes in customs matters. Reliance solely on the general 

information in this pamphlet may not be considered reasonable care.

Additional information may also be obtained from U.S. Customs and Border Protection 

ports of entry. Please consult your telephone directory for an office near you. The 

listing will be found under U.S. Government, Department of Homeland Security. 

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21

“Your Comments are Important” 

The Small Business and Regulatory Enforcement Ombudsman and 10 regional 

Fairness Boards were established to receive comments from small businesses about 

Federal agency enforcement activities and rate each agency’s responsiveness to small 

business. If you wish to comment on the enforcement actions of U.S. Customs and 

Border Protection, call 1-888-REG-FAIR (1-888-734-3247). 

REPORT SMUGGLING 1-800-BE-ALERT 

Visit our Internet web site: http://www.cbp.gov