A N A M E R I C A N N A T I O N A L S T A N D A R D
ASME B18.31.2-2008
Continuous and
Double-End Studs
(Inch Series)
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ASME B18.31.2-2008
Continuous and
Double-End Studs
(Inch Series)
A N AM E R I C A N N AT I O N A L S TA N D A R D
Copyright ASME International
Provided by IHS under license with ASME Licensee=FMC Technologies /5914950002
Not for Resale, 05/13/2009 00:38:22 MDTNo reproduction or networking permitted without license from IHS
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Date of Issuance: November 24, 2008
This Standard will be revised when the Society approves the issuance of a new edition. There will
be no addenda issued to this edition.
ASME issues written replies to inquiries concerning interpretations of technical aspects of this
Standard. Periodically, certain actions of the ASME B18 Committee may be published as Cases. Cases
and interpretations are published on the ASME Web site under the Committee Pages at
http://cstools.asme.org as they are issued.
ASME is the registered trademark of The American Society of Mechanical Engineers.
This code or standard was developed under procedures accredited as meeting the criteria for American National
Standards. The Standards Committee that approved the code or standard was balanced to assure that individuals from
competent and concerned interests have had an opportunity to participate. The proposed code or standard was made
available for public review and comment that provides an opportunity for additional public input from industry, academia,
regulatory agencies, and the public-at-large.
ASME does not “approve,” “rate,” or “endorse” any item, construction, proprietary device, or activity.
ASME does not take any position with respect to the validity of any patent rights asserted in connection with any
items mentioned in this document, and does not undertake to insure anyone utilizing a standard against liability for
infringement of any applicable letters patent, nor assume any such liability. Users of a code or standard are expressly
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ASME accepts responsibility for only those interpretations of this document issued in accordance with the established
ASME procedures and policies, which precludes the issuance of interpretations by individuals.
No part of this document may be reproduced in any form,
in an electronic retrieval system or otherwise,
without the prior written permission of the publisher.
The American Society of Mechanical Engineers
Three Park Avenue, New York, NY 10016-5990
Copyright © 2008 by
THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS
All rights reserved
Printed in U.S.A.
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CONTENTS
Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv
Committee Roster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
Correspondence With the B18 Committee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2 Comparison With ISO Documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
3 Referenced Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
4 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
5 Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
6 Body Diameter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
7 Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
8 Points . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
9 Thread Length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
10 Screw Threads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
11 Materials and Mechanical Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
12 Identification Symbols. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
13 Finish . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
14 Workmanship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
15 Straightness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
16 Inspection and Quality Assurance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
17 Dimensional Conformance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
18 Clearance Holes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
19 Designation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Tables
1 Dimensions for Continuous Thread Studs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2 Dimensions for Clamping Type Studs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Dimensions for Tap End Studs (1.5D Engagement) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 Body Diameters for Double End Studs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Length Tolerances for Studs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Mandatory Appendix
I Stud Straightness, Referee Gage, and Gaging Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
iii
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FOREWORD
ASME Standards Committee B18 for the Standardization of Bolts, Nuts, Rivets, Screws, Washers,
and Similar Fasteners (formerly American National Standards Committee B18) was organized
in March 1922 as Sectional Committee B18 under the aegis of the American Engineering Standards
Committee (later the American Standards Association, then the United States of America
Standards Institute, and, as of October 6, 1969, the American National Standards Institute, Inc.)
with the Society of Automotive Engineers and the American Society of Mechanical Engineers as
joint sponsors.
In 1995, the SAE Ship Systems and Equipment Committee that was preparing fastener part
standards for the shipbuilding industry asked ASME Committee B18 if there was an interest in
developing dimensional standards for studs. At the December 1995 meeting of B18 in Atlanta,
it was reported that a survey by ASME showed considerable interest in establishing a subcommit-
tee to develop stud standards, and 11 representatives indicated their willingness to serve on a
subcommittee. Subcommittee 31 was established, and draft SAE inch and metric stud standards
were distributed for review.
The first meeting of Subcommittee 31 on studs was held in April 1996, in conjunction with
the ASME B18 meetings in Chicago. Existing stud standards (IFI 136, Studs and Bolts, and IFI
528, Metric Studs and Bolts) were compared with the draft SAE standards [J2271, Part Standard
for Studs — Continuous and Double End (Inch Series), and J2271M, Part Standard for Studs —
Continuous and Double End (Metric)]. The Subcommittee then identified the configurations to
be developed along with thread sizes and diameters to be covered. It was determined to develop
both inch and metric standards covering both continuously threaded and double ended studs.
A decision to develop the metric standard first was unanimously passed.
As the metric standard B18.31.1M was developed, little effort was devoted to the inch standard
until 2005. In April 2005, the Subcommittee developed basic requirements for the inch studs that
were similar to the metric studs, with the addition of interference-fit studs using ASME B1.12
threads. A draft was reviewed at the November 2006 meeting with a number of format changes
suggested. How to define the nominal length for tap end studs was discussed, and a motion
was approved to identify the nominal length as the overall length rather than the protrusion
length when installed as used in ASME B18.31.1M per ISO 225 requirements.
In November 2006, the Subcommittee decided that diameters from 1⁄4 in. to 4 in. would be
covered although at the previous meeting it had been agreed to cover diameters down to Size
No. 0. The nominal length for tap end studs was again revisited without a consensus being
reached. At the April 2007 meeting, examples of both methods of identifying the nominal length
of tap studs were reviewed, and it was determined to use the overall length as the nominal length
as this had been the past convention for inch studs in the United States.
A draft was balloted prior to the November 2007 meeting and several disapprovals were
resolved at the meeting. It was agreed that the maximum nut end thread length would be deleted
in favor of a total thread length to the last scratch, which would be the minimum thread length
plus five thread pitches. As a result, thread gaging is simplified without affecting the overall
suitability of the studs.
A reconsideration draft was balloted prior to the April 2008 meeting. The only disapproval
was withdrawn prior to the meeting, and the Subcommittee approved several minor editorial
corrections at the meeting.
This edition was approved by the American National Standards Institute on August 4, 2008.
iv
Copyright ASME International
Provided by IHS under license with ASME Licensee=FMC Technologies /5914950002
Not for Resale, 05/13/2009 00:38:22 MDTNo reproduction or networking permitted without license from IHS
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ASME B18 COMMITTEE
Standardization of Bolts, Nuts, Rivets, Screws,
Washers, and Similar Fasteners
(The following is the roster of the Committee at the time of approval of this Standard.)
STANDARDS COMMITTEE OFFICERS
D. A. Clever, Chair
R. D. Strong, Vice Chair
R. L. Crane, Secretary
STANDARDS COMMITTEE PERSONNEL
V. Cartina, Continental-Aero
D. A. Clever, Deere & Co.
A. P. Cockman, Ford Motor Co.
B. D. Burnside, Alternate, Ford Motor Co.
R. L. Crane, The American Society of Mechanical Engineers
A. C. DiCola, Wrought Washer Co.
B. A. Dusina, Federal Screw Works
J. S. Foote, Contributing Member, Trade Association Management
Inc.
D. S. George, ND Industries
J. Greenslade, Industrial Fasteners Institute
J. J. Grey, Contributing Member, Fastener Consulting Services, Inc.
B. Hasiuk, Contributing Member, Defense Industrial Supply Center
Philadelphia
A. Herskovitz, Consultant
J. Hubbard, Contributing Member, Rockford Fastener, Inc.
J. Jennings, Contributing Member, Naval Surface Warfare Center
M. Keller, Contributing Member, Consultant
SUBCOMMITTEE 31 — THREADED STUDS
W. K. Wilcox, Chair, Consultant
C. A. Dugal, Vice Chair, Texas Screw Products
R. L. Crane, Secretary, The American Society of Mechanical
Engineers
J. F. Braden, Fasteners Unlimited
D. A. Clever, Deere & Co.
D. S. George, ND Industries
J. Greenslade, Industrial Fasteners Institute
A. Herskovitz, Consultant
v
J. F. Koehl, Contributing Member, Spirol International Group
W. H. Kopke, ITW Assembly Shakeproof
J. G. Langenstein, Honorary Member, Consultant
W. J. Lutkus, Heli-Coil Emhart
D. McCrindle, Canadian Fasteners Institute
M. D. Prasad, Contributing Member, General Motors Corp.
W. L. Sakowski, Account Managers, LLC
S. Savoji, ITW Medalist
W. Schevey, Contributing Member, BGM Fastener Co., Inc.
W. R. Stevens, Ramco
R. D. Strong, General Motors Corp.
S. W. Vass, Consultant
C. B. Wackrow, Contributing Member, MNP Corp.
W. K. Wilcox, Consultant
C. B. Williamson, Fastenal Co.
C. J. Wilson, Consultant
R. B. Wright, Contributing Member, Wright Tool Co.
J. G. Zeratsky, National Rivet & Manufacturing Co.
J. Jennings, Naval Surface Warfare Center
J. F. McCarrick, Defense Supply Center Philadelphia
R. B. Meade, Atrona Material Testing Laboratories, Inc.
W. Schevey, BGM Fastener Co., Inc.
G. M. Simpson, Semblex Corp.
W. R. Stevens, MNP Corp.
R. D. Strong, General Motors Corp.
C. B. Wackrow, MNP Corp.
C. B. Williamson, Fastenal Co.
C. J. Wilson, Industrial Fasteners Institute
Copyright ASME International
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CORRESPONDENCE WITH THE B18 COMMITTEE
General. ASME Standards are developed and maintained with the intent to represent the
consensus of concerned interests. As such, users of this Standard may interact with the Committee
by requesting interpretations, proposing revisions, and attending Committee meetings. Corre-
spondence should be addressed to:
Secretary, B18 Standards Committee
The American Society of Mechanical Engineers
Three Park Avenue
New York, NY 10016-5990
Proposing Revisions. Revisions are made periodically to the Standard to incorporate changes
that appear necessary or desirable, as demonstrated by the experience gained from the application
of the Standard. Approved revisions will be published periodically.
The Committee welcomes proposals for revisions to this Standard. Such proposals should be
as specific as possible, citing the paragraph number(s), the proposed wording, and a detailed
description of the reasons for the proposal, including any pertinent documentation.
Proposing a Case. Cases may be issued for the purpose of providing alternative rules when
justified, to permit early implementation of an approved revision when the need is urgent, or to
provide rules not covered by existing provisions. Cases are effective immediately upon ASME
approval and shall be posted on the ASME Committee Web page.
Requests for Cases shall provide a Statement of Need and Background Information. The request
should identify the standard, the paragraph, figure or table number(s), and be written as a
Question and Reply in the same format as existing Cases. Requests for Cases should also indicate
the applicable edition(s) of the standard to which the proposed Case applies.
Interpretations. Upon request, the B18 Standards Committee will render an interpretation of
any requirement of the Standard. Interpretations can only be rendered in response to a written
request sent to the Secretary of the B18 Standards Committee.
The request for an interpretation should be clear and unambiguous. It is further recommended
that the inquirer submit his/her request in the following format:
Subject: Cite the applicable paragraph number(s) and the topic of the inquiry.
Edition: Cite the applicable edition of the Standard for which the interpretation is
being requested.
Question: Phrase the question as a request for an interpretation of a specific requirement
suitable for general understanding and use, not as a request for an approval
of a proprietary design or situation. The inquirer may also include any plans
or drawings, which are necessary to explain the question; however, they
should not contain proprietary names or information.
Requests that are not in this format may be rewritten in the appropriate format by the Committee
prior to being answered, which may inadvertently change the intent of the original request.
ASME procedures provide for reconsideration of any interpretation when or if additional
information that might affect an interpretation is available. Further, persons aggrieved by an
interpretation may appeal to the cognizant ASME Committee or Subcommittee. ASME does not
“approve,” “certify,” “rate,” or “endorse” any item, construction, proprietary device, or activity.
Attending Committee Meetings. The B18 Standards Committee regularly holds meetings, which
are open to the public. Persons wishing to attend any meeting should contact the Secretary of
the B18 Standards Committee.
vi
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ASME B18.31.2-2008
CONTINUOUS AND DOUBLE-END STUDS (INCH SERIES)
1 INTRODUCTION
1.1 Scope
1.1.1 This Standard covers the complete dimen-
sional and general data for continuous thread and dou-
ble-end inch-dimensioned studs recognized as
American National Standard. The following configura-
tions are covered:
continuous thread stud: studs that are threaded over their
complete length.
double-end stud (clamping type — identical ends): studs
with screw threads of the same length and configuration
on each end. This type of stud serves the function of
clamping two bodies together with a nut on each end.
double-end stud (tap end type): a stud designed to be
installed in a tapped hole and usually with different
threaded lengths on each end. For the tap end of the
studs, both regular unified threads and interference-fit
threads are covered.
Double-end studs of the following body diameters
are covered:
(a) reduced diameter body (see para. 6.1 for
dimensions)
(b) full body (see para. 6.2 for dimensions)
1.1.2 The inclusion of dimensional data in this
Standard is not intended to imply that all