ASME B18.8.

2-2020
[Revision of ASME B18.8.2-2000 (R2010)]

Taper Pins, Dowel Pins,

Straight Pins, Grooved
Pins, and Spring Pins
(Inch Series)

A N A M E R I C A N N AT I O N A L STA N DA R D
 ASME B18.8.2-2020
[Revision of ASME B18.8.2–2000 (R2010)]

Taper Pins, Dowel Pins,

Straight Pins, Grooved
Pins, and Spring Pins
(Inch Series)

AN AMERICAN NATIONAL STANDARD

x
 Date of Issuance: December 21, 2020

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 CONTENTS

Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
Committee Roster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii
Correspondence With the B18 Committee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii

1 Introduction . . . ................................................... . . . . 1
2 General Data for Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
3 General Data for Taper Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
4 General Data for Hardened Ground Machine Dowel Pins . . . . . . . . . . . . . . . . . . . . . . . . 5
5 General Data for Hardened Ground Production Dowel Pins . . . . . . . . . . . . . . . . . . . . . . 9
6 General Data for Unhardened Ground Dowel Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
7 General Data for Straight Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
8 General Data for Grooved Pins, Grooved Drive Studs, and Grooved T-Head Cotter Pins . 16
9 General Data for Spring Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Nonmandatory Appendices
A Recommended Hole Specifications for Taper Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
B Double Shear Testing of Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
C Type B, C, and D Grooved Pin Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
D Conversion Table for SAE and UNS Material Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Figures
4.2.1.1-1 Point Concentricity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
A-1-1 Step Drill Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
A-1-2 Drill Diameter Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
B-1-1 Typical Pin Shear Test Fixtures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Tables
3.1.1-1 Dimensions of Taper Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3.5.3-1 Standard Sizes and Lengths of Taper Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4.1.1-1 Dimensions of Hardened Ground Machine Dowel Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
4.3.3-1 Preferred Sizes and Lengths of Hardened Ground Machine Dowel Pins . . . . . . . . . . . . . . . . . 7
4.9.1-1 Suggested Hole Sizes for Standard Series Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5.1.1-1 Dimensions of Hardened Ground Production Dowel Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
5.3.3-1 Preferred Sizes and Lengths of Hardened Ground Production Dowel Pins . . . . . . . . . . . . . . . 10
5.8.1-1 Suggested Hole Diameters for Hardened Ground Production Dowel Pins . . . . . . . . . . . . . . . . 11
6.1.1-1 Dimensions of Unhardened Ground Dowel Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
6.3.3-1 Preferred Sizes and Lengths of Unhardened Ground Dowel Pins . . . . . . . . . . . . . . . . . . . . . . 13
6.8-1 Suggested Hole Diameters for Unhardened Ground Dowel Pins . . . . . . . . . . . . . . . . . . . . . . 14
7.1.1-1 Dimensions of Chamfered and Square End Straight Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

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8.2.1-1 Dimensions of Grooved Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
8.2.1-2 Dimensions of Round-Head Grooved Drive Studs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.2.1-3 Dimensions of Grooved T-Head Cotter Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
8.2.2-1 Expanded Diameters for Grooved Pins Made From Low Carbon or Alloy Steel . . . . . . . . . . . . 21
8.2.2-2 Expanded Diameters for Grooved Pins Made From Corrosion Resistant Steel and Monel . . . . 22
8.5.3-1 Standard Sizes and Lengths of Grooved Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
8.5.3-2 Pilot Length Dimensions for Round-Head Grooved Drive Studs . . . . . . . . . . . . . . . . . . . . . . . 25
8.5.3-3 Groove Length Dimensions for Grooved T-Head Cotter Pins . . . . . . . . . . . . . . . . . . . . . . . . . 26
8.7-1 Minimum Performance Requirements of Grooved Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
8.8-1 Recommended Hole Sizes for Unplated Grooved Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
8.8-2 Recommended Hole Sizes for Unplated Grooved Drive Studs . . . . . . . . . . . . . . . . . . . . . . . . 27
9.4.2-1 Tolerance on Length of Spring Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
9.4.3-1 Practical Sizes and Lengths of Coiled- and Slotted-Type Spring Pins . . . . . . . . . . . . . . . . . . . 29
9.4.4-1 Dimensions of Slotted-Type Spring Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
9.4.4-2 Dimensions of Coiled-Type Spring Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
9.6-1 Hardness Requirements for Slotted- and Coiled-Type Spring Pins . . . . . . . . . . . . . . . . . . . . . 33
A-1-1 Drill Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
C-1 Dimensions of Grooved Pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
D-1 Conversion Table for SAE and UNS Material Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . 40

iv
 FOREWORD

The need for a standard covering machine pins was recognized by industry as far back as March, 1926, when the
Sectional Committee on the Standardization of Machine Pins was organized under the procedure of the American Stan-
dards Association (later 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.
For the next year or two an effort was made via correspondence to develop a basis on which a standard for straight,
taper, split, and dowel pins might be established. This correspondence exposed a distinct difference of opinion on the part
of the manufacturers and users of taper machine pins, which seemed to discourage the members of the committee from
attempting standardization on any of the types of pins within its scope. The sponsor organization made frequent efforts to
revive this project through letters and the distribution of technical literature on this general subject, without avail.
In December, 1941, during its periodic review of Society-sponsored standards, the ASME Standardization Committee
decided that reviving the project was unlikely and voted (subject to acceptance by the sponsors) to suggest to the ASA the
transfer of this project to Sectional Committee B5 on the Standardization of Small Tools and Machine Tool Elements. The
sponsors agreed and on July 7, 1942, the ASA sanctioned this action and Sectional Committee B43 was discharged and the
project was officially transferred to Sectional Committee B5.
At its meeting in December, 1942, Sectional Committee B5 voted to enlarge its scope to include machine pins. Technical
Committee No. 23 was subsequently established and charged with the responsibility for technical content of standards
covering machine pins. This group held its first meeting on November 30, 1943, at which time a subgroup on Correlation
and Recommendations was appointed and it was voted to include clevis pins in addition to the other pin types already
under consideration. Several drafts were prepared by the subgroup, distributed for critical comment to users, manu-
facturers, and general interests and revised and resubmitted for comments. This action finally resulted in acceptance by
Technical Committee 23 of a draft dated November, 1945. Proofs of the draft, with a date of October, 1946 were dis-
tributed to the members of Sectional Committee B5 for letter ballot approval. After the approval of the Sectional
Committee, the proposal was next approved by the sponsor bodies, and presented to the American Standards Association
for approval as an American Standard. This designation was granted on July 7, 1947.
Following the issuance of the standard it became apparent that the table on cotter pins needed revision. Accordingly in
1953 a proposed revision was submitted to the Sectional Committee. After attaining Sectional Committee and sponsor
approval this revision was approved by the American Standards Association on July 9, 1954 as ASA B5.20-1954.
In 1956 and 1957, in response to requests from industry, extensive changes were incorporated into a proposed
revision. These included revisions to chamfer values and tolerances on straight pins and unhardened ground
dowel pins; revisions to under-head-to-hole, pin end dimensions, and hole size tolerances on clevis pins; addition
of chisel point to cotter pin end-styles; and the incorporation of coverage on grooved pins. Following Sectional Committee
and sponsor approvals, this revision was adopted by the American Standards Association on March 25, 1958, as ASA
B5.20-1958.
In late 1961, Sectional Committee B5 suggested that Sectional Committee B18 on the standardization of bolts, nuts,
rivets, screws, and similar fasteners assume jurisdiction over standards for pins. Recognizing that the bulk of the products
covered in the ASA B5.20 standards were fastener rather than machine oriented, this recommendation was supported by
the B18 Committee and officially endorsed by the sponsor organizations. Consequently this Committee, at the September
14, 1962 meeting, decreed that Subcommittee 23* should be formed to review and update the pin standard.
At the initial meeting, held on June 3, 1964, Subcommittee 23* decided to add standards for spring pins and to establish
seven subgroups, each of which would have technical responsibility for specific pin products, and to publish respective
products under separate cover as projects were completed.
Over several years, work by Subgroups 2, 3, 4, 5, and 6 culminated in a proposal for revising the standards covering
taper, dowel, straight, and grooved pins and including coverage for spring pins (which was approved through letter ballot
by Subcommittee 8 on February 24, 1977). After acceptance by American National Standards Committee B18 and the
sponsor organizations, this document was submitted to the American National Standards Institute for approval as an
American National Standard. Approval was granted on April 5, 1978 and the standard was published under the des-
ignation ANSI B18.8.2, superseding in part the coverage provided in ASA B5.20-1958.

* As of April 1, 1966 Subcommittee 23 was redesignated Subcommittee 8.

v
 The B18.8.2-1978 edition was reaffirmed without change in 1989. The 1995 edition of B18.8.2 contained significant
changes to the 1989 edition of B18.8.2 and was developed by the American Society of Mechanical Engineers B18
Committee on Fasteners. ASME B18.8.2-2000 was approved by the American National Standards Institute on June
22, 2000, and reaffirmed in 2010.
In 2017, the committee agreed to revise this Standard. The technical request prompting the revision began with some
confusion in the industry regarding the diameter (A) of grooved pins. This revision clarifies that this dimension may be
affected during the grooving process and shall not be cause for rejection. ASME B18.8.2-2020 was initially approved by
ANSI as an American National Standard on April 16, 2020. However, publication was postponed to allow the committee to
remove unrelated dimensions from Table C-1. ASME B18.8.2-2020 was again approved by ANSI as an American National
Standard on October 30, 2020.

vi
 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

W. Guth, Chair
J. Medcalf, Vice Chair
A. L. Guzman Rodriguez, Secretary

STANDARDS COMMITTEE PERSONNEL

T. Anderson, Bay Bolt J. F. McCarrick, Alternate, Defense Supply Center — Philadelphia
L. Borowski, Greenslade and Co., Inc. M. Byrne, Contributing Member, General Fasteners Co.
S. Brahimi, Industrial Fasteners Institute D. A. Clever, Contributing Member, Consultant
B. Cao, Infasco R. W. Davidson, Contributing Member, Endries International, Inc.
V. Cartina, Hi-Performance Fastening Systems J. J. Grey, Contributing Member, Fastener Consulting Services, Inc.
L. Claus, NNI Training and Consulting, Inc. J. C. Jennings, Contributing Member, Naval Surface Warfare Center —
A. P. Cockman, Consultant Philadelphia
D. S. George, Michigan Metal Coating M. Kaindl, Contributing Member, Aztech Locknut Co.
W. Guth, Electric Boat Corp. D. Korneffel, Contributing Member, Cadenas PARTsolutions
A. L. Guzman Rodriguez, The American Society of Mechanical M. D. Prasad, Contributing Member, Global M&F Solutions, Inc.
Engineers J. J. Stoczanskyj, Contributing Member, Beacon Fasteners and Compo-
J. Medcalf, Field Fastener nents, Inc.
M. Q. Muhammad, Defense Logistics Agency — Troop Support R. D. Strong, Contributing Member, Lear Corp.
J. P. Nash, Caterpillar, Inc. C. G. Vertullo, Contributing Member, Carver Engineering and Manu-
F. J. Perry, John Deere facturing, Inc.
C. B. Williamson, Fastenal Co. C. J. Wilson, Contributing Member, Consultant

SUBCOMMITTEE 8 — MACHINE PINS

A. Barry, Chair, Consultant C. G. Vertullo, Carver Engineering and Manufacturing, Inc.
J. F. Koehl, SPIROL International Corp. C. J. Wilson, Consultant
R. Lund, Fastenal Co. D. Clever, Contributing Member, Consultant
D. A. Thonus, Fastar, Inc.

vii
 CORRESPONDENCE WITH THE B18 COMMITTEE

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Secretary, B18 Standards Committee

The American Society of Mechanical Engineers
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New York, NY 10016-5990
http://go.asme.org/Inquiry

Proposing Revisions. Revisions are made periodically to the Standard to incorporate changes that appear necessary
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information.

viii
 Requests that are not in the format described above may be rewritten in the appropriate format by the Committee prior
to being answered, which may inadvertently change the intent of the original request.
Moreover, ASME does not act as a consultant for specific engineering problems or for the general application or
understanding of the Standard requirements. If, based on the inquiry information submitted, it is the opinion of
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Attending Committee Meetings. The B18 Standards Committee regularly holds meetings and/or telephone confer-
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Page at http://go.asme.org/B18committee.

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INTENTIONALLY LEFT BLANK

x
 ASME B18.8.2-2020

TAPER PINS, DOWEL PINS, STRAIGHT PINS, GROOVED PINS, AND

SPRING PINS (INCH SERIES)

1 INTRODUCTION ASME B18.24, Part Identifying Number (PIN) Code System

for B18 Fastener Products
1.1 Scope ASME B46.1, Surface Texture (Surface Roughness, Wavi-
ness, and Lay)
1.1.1 This Standard covers the dimensional and
ASME Y14.5, Dimensioning and Tolerancing
general data for taper pins, dowel pins, straight pins,
Publisher: The American Society of Mechanical Engineers
grooved pins, and spring pins. Also included are appen-
(ASME), Two Park Avenue, New York, NY 10016-5990
dices providing supplementary information for the dril-
(www.asme.org)
ling of holes for taper pins and the testing of pins in double
shear.
1.1.2 The inclusion of dimensional data in this Stan- 1.7 Related Standards
dard is not intended to imply that all the products Standards for clevis pins and cotter pins, inch series are
described are stock production sizes. Consumers published in ASME B18.8.1.
should consult with manufacturers concerning lists of
stock production sizes. 1.8 Part Identifying Number

1.2 Comparison With ISO Standards For a Part Identifying Number, refer to ASME B18.24.

Since these are inch fastener standards, there are no 2 GENERAL DATA FOR PINS
comparable ISO standards.
2.1 Types of Pins
1.3 Dimensions
2.1.1 Taper Pins. Taper pins shall have a uniform taper
Unless otherwise specified, all dimensions are in inches. over the pin length with both ends crowned. Most sizes are
All dimensions shall apply before coating. Symbols speci- supplied in both commercial and precision classes, the
fying geometric characteristics are in accord with ASME latter having generally tighter tolerances and being
Y14.5. more closely controlled in manufacture. Dimensions
for both classes are given in Table 3.1.1-1.
1.4 Options
2.1.2 Dowel Pins. The following three varieties of
Where specified, options shall be at the discretion of the dowel pins are covered.
manufacturer unless otherwise agreed upon by the manu-
facturer and purchaser. Special materials, coatings, lubri- 2.1.2.1 Hardened Ground Machine Dowel Pins. This
cation, or packaging requirements shall be specified by the variety of hardened dowel pins shall have ground cylin-
purchaser. drical sides with one end pointed slightly to enter mating
drive-fit holes and the other end rounded or crowned for
1.5 Terminology driving purposes. They are available in standard and over-
size diameter series to satisfy initial and replacement re-
For definitions of terminology not specified in this Stan-
quirements, respectively. Dimensions for both series are
dard, refer to ASME B18.12.
given in Table 4.1.1-1.
1.6 Referenced Standards 2.1.2.2 Hardened Ground Production Dowel Pins.
The following is a list of publications referenced in this This variety of hardened dowel pin shall have ground cy-
Standard. The latest edition shall be used. lindrical sides with both ends rounded sufficiently to
enable the pin to be pressed into drive-fit holes. Dimen-
ASME B18.8.1, Clevis Pins and Cotter Pins (Inch Series) sions are given in Table 5.1.1-1.
ASME B18.12, Glossary of Terms for Mechanical Fasteners
ASME B18.18, Quality Assurance for Fasteners