Screw Thread Gaging Systems for Acceptability: Inch and Metric Screw Threads

(UN, UNR, UNJ, M, and MJ)

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

Intentionally left blank

ASME B1.3-2007

(Revision of ASME B1.3M-1992)

Screw Thread Gaging Systems for Acceptability: Inch and Metric Screw Threads

(UN, UNR, UNJ, M, and MJ)

AN AMERICAN NA TIONAL S T AND ARD

Three Park Avenue • New York, NY 10016

Date of Issuance: October 12, 2007

This Standard will be revised when the Society approves the issuance of a new edition. There will be no addenda or written interpretations of the requirements of this Standard issued to this edition.

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The American Society of Mechanical Engineers Three Park Avenue, New York, NY 10016-5990

Copyright © 2007 by

THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS

All rights reserved Printed in U.S.A.

CONTENTS

Foreword iv

Committee Roster v

Correspondence With the B1 Committee vi

1. General 1

2. Reference Documents 1

3. Screw Thread Gages and Measuring Equipment 1

4. Gaging Systems 1

5. Gaging Requirements 2

6. Acceptability 2

7. Designation 3

Tables

1. Screw Thread Gages and Measuring Equipment for External Product Thread Characteristics 4

2. Screw Thread Gages and Measuring Equipment for Internal Product Thread Characteristics 8

3. Gaging Systems for External Threads 12

4. Gaging Systems for Internal Threads 13

iii

FOREWORD

1. The 1986 edition of this Standard was a combination of ANSI B1.3-1979 and ANSI B1.3M-1981. These earlier versions of this Standard were based upon the following instructions as defined by the B1 Committee at its meeting on October 7, 1976, which charged the B1.3 Subcommittee with the responsibility of preparing these documents.

   The Subcommittee was to prepare a catalog of gages and gaging systems so that each gage or gaging system would be defined only in terms of the dimension(s) controlled and so that any material of an editorial nature that could be construed as giving preference to one gage or gaging system over another would be eliminated, as outlined in the following three statements:

   1. All references to referee gaging methods are to be eliminated from all B1 documents.

   2. A catalog of gaging systems is to be prepared by the B1.3 Subcommittee so that any description of the gage relates only to the specific dimension(s) it controls. All material of an editorial nature that could be construed as giving preference will be eliminated.

   3. The level of dimensional acceptability shall be determined by the threaded product application and specified by American National Standards or other product standards, or by procurement drawings or documents.

      Subsequently, the Subcommittee decided to combine these previous standards into one docu- ment and designate it ANSI/ASME B1.3M-1986, Screw Thread Gaging Systems for Dimensional Acceptability — Inch and Metric Screw Threads (UN, UNR, UNJ, M, and MJ).

2. The 1992 edition included the following specific changes:

   1. elimination of internal snap gages

   2. addition of best wire size radius contacts to minimum material thread groove measure- ment gaging

   3. clarification of out-of-round indicating gaging in Tables 1 and 2

   4. addition of a reference to ASME B46.1, Surface Texture, to provide roughness average guidelines to be used for the evaluation of the surface texture of threaded products

   5. addition of linear and coordinate measuring machines to the equipment included for thread evaluation

   6. clarification that System 23 checks are not all mandatory

   7. clarification relating to the measurement of changes in diameter size because of out-of- roundness conditions

3. The 2007 edition includes the following specific changes:

   1. removal of the words dimensional and control(s), and replacement with the wording inspect/ evaluate (and their related forms), because gages do not control the product dimension.

   2. elimination of references to ASME B1.18M and B1.19M, due to those standards having previously been withdrawn. This also eliminates any reference to System 21A and its gages as previously listed in Tables 1, 2, 3, and 4 (B and C NOT GO segments and rolls, commonly referred to as a double NOT GO).

   3. elimination of the use of cast replica determination of pitch diameter (and related features) for internal product inspection/evaluation.

   4. qualification notes under Tables 1 and 2 with regard to variable gage inspection of functional diameter.

   5. changed the numbering system in Tables 1, 2, 3, and 4 to provide consistency in numbering from table to table.

      Suggestions for improvement of this Standard are welcome. They should be sent to Secretary, ASME B1 Standards Committee, Three Park Avenue, New York, NY 10016-5990.

      This revision was approved as an American National Standard on March 5, 2007.

      
      

      iv

      
      

      ASME B1 COMMITTEE

      Screw Threads

      (The following is the roster of the Committee at the time of approval of this Standard.)

      
      

      STANDARDS COMMITTEE OFFICERS

      1. L. Barrows, Chair

D. S. George, Vice Chair

A. L. Guzman, Secretary

G. L. Allen, L. S. Starret Co.

STANDARDS COMMITTEE PERSONNEL

B. Larzelere, Corresponding Member, Deltronic Corp.

A. L. Barrows, Kennametal Industrial Products Group

F. G. Calderone, Corresponding Member, Quality Systems Implementers

L. N. Dixon, Jr., General Electric

R. Dodge, Pennoyer Dodge Co.

1. A. Flannery, Corresponding Member, Mercury Gage Co.

2. N. Frost, Defense Supply Center Philadelphia

J. O. Gehret, Vermont Thread Gage

D. S. George, Ford Motor Co.

J. R. Gervasi, Kerr Lakeside Inc.

J. Greenslade, Greenslade & Co.

J. Vance, Alternate, Greenslade & Co.

A. L. Guzman, The American Society of Mechanical Engineers

R. J. Hukari, SPS Technologies

L. C. Johnson, The Johnson Gage Co.

D. D. Katz, Precision Fittings

R. P. Knittel, Leitech-US, Ltd.

1. L. Lord, Corresponding Member, Consultant

2. H. McWilliams, PMC Lone Star

D. Skierski, Alternate, Sterling Gage & Calibration LLC

D. Miskinis, Kennametal Industrial Products Group

W. R. Newman, Consultant

D. R. Oas, Seaway Bolt & Specials Corp.

M. W. Rose, Glastonbury Southern Gage

W. A. Watts, Alternate, Glastonbury Southern Gage

E. Schwartz, Consultant

R. H. Searr, Member Emeritus, Mak Tool & Gage

B. F. Sheffler, Dresser-Rand Co.

A. D. Shepherd, Jr., Emuge Corp.

R. D. Strong, General Motors

A. F. Thibodeau, Member Emeritus, Swanson Tool Manufacturing Co.

R. E. Vincent, Jr., General Plug Manufacturing

C. Wilson, Industrial Fasteners Institute

F. W. Akstens, Alternate, Industrial Fasteners Institute

R. Dodge, Chair, Pennoyer Dodge Co.

G. L. Allen, L. S. Starret Co.

SUBCOMMITTEE 3 — ACCEPTABILITY

B. Larzelere, Corresponding Member, Deltronic Corp.

L. L. Lord, Corresponding Member, Consultant

A. L. Barrows, Kennametal Industrial Products Group

F. G. Calderone, Corresponding Member, Quality Systems Implementers

M. Cox, Corresponding Member, Consultant

L. N. Dixon, Jr., General Electric

G. A. Flannery, Mercury Gage Co.

D. S. George, Ford Motor Co.

J. Greenslade, Greenslade & Co.

J. Vance, Alternate, Greenslade & Co.

R. J. Hukari, SPS Technologies

L. C. Johnson, The Johnson Gage Co.

J. M. Kane, Boeing Corp.

D. D. Katz, Precision Fittings

M. H. McWilliams, PMC Lone Star

D. Skierski, Alternate, Sterling Gage & Calibration LLC

D. Miskinis, Kennametal Industrial Products Group

W. R. Newman, Consultant

M. W. Rose, Glastonbury Southern Gage

E. Schwartz, Consultant

R. H. Searr, Mak Tool & Gage

B. F. Sheffler, Dresser-Rand Co.

J. D. Smith, Hi-Shear Corp.

R. D. Strong, General Motors

W. A. Watts, Glastonbury Southern Gage

C. Wilson, Industrial Fasteners Institute

F. W. Akstens, Alternate, Industrial Fasteners Institute

v

CORRESPONDENCE WITH THE B1 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 proposing revisions and attending Committee meetings. Correspondence should be addressed to:

Secretary, B1 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.

Attending Committee Meetings. The B1 Standards Committee regularly holds meetings, which are open to the public. Persons wishing to attend any meeting should contact the Secretary of the B1 Standards Committee.

vi

ASME B1.3-2007

SCREW THREAD GAGING SYSTEMS FOR ACCEPTABILITY: INCH AND METRIC SCREW THREADS (UN, UNR, UNJ, M, AND MJ)

1. GENERAL

   1. This Standard presents screw thread gaging sys- tems suitable for determining the acceptability of UN, UNR, UNJ, M, and MJ screw threads on externally and internally threaded products. It establishes the criteria for screw thread acceptance when a gaging system is used.

   2. A screw thread gaging system comprises a list of screw thread characteristics that must be inspected/ evaluated to establish the acceptability of the screw threads on a threaded product and the gage(s) which shall be used when inspecting/evaluating those charac- teristics.

   3. Federal Government Use. This Standard is approved by the Department of Defense and federal agencies, and is incorporated into FED-STD-H28/20, Screw Thread Standards for Federal Services, Section

      20. The use of this Standard by the federal government is subject to all the requirements and limitations of FED-STD-H28/20.

      
      

2. REFERENCE DOCUMENTS

   The latest issues of the following documents form a part of this Standard to the extent specified herein.

   ASME B1.1, Unified Inch Screw Threads (UN and UNR Thread Form)1

   ANSI/ASME B1.2, Gages and Gaging for Unified Inch Screw Threads1

   ASME B1.7, Screw Threads: Nomenclature, Definitions, and Letter Symbols1

   ASME B1.13M, Metric Screw Threads: M Profile1 ASME B1.15, Unified Inch Screw Threads (UNJ Thread

   Form)

   ANSI/ASME B1.16M, Gages and Gaging for Metric M Screw Threads1

   ASME B1.21M, Metric Screw Threads: MJ Profile1

   ANSI/ASME B1.22M, Gages and Gaging for MJ Series Metric Screw Threads1

   ASME B46.1, Surface Texture (Surface Roughness, Waviness, and Lay)1

   
   

   1 May also be obtained from American National Standards Insti- tute, 25 West 43rd Street, New York, NY 10036.

   ASME/ANSI B47.1, Gage Blanks1

   Publisher: The American Society of Mechanical Engineers (ASME), Three Park Ave, New York, NY 10016-5990; Order Department: 22 Law Drive, Box 2300, Fairfield, NJ 07007-2300

   
   

3. SCREW THREAD GAGES AND MEASURING EQUIPMENT

   1. Tables 1 and 2, for external and internal screw threads, respectively, are listings of screw thread gages, gaging elements, and measuring equipment.

      NOTE: Throughout the remainder of this Standard, the term gage includes any gages, gaging elements, and measuring equipment listed in Tables 1 and 2. See para. 5(d).

      For each gage, these tables specify the thread charac- teristic(s) for which the gages are designated for determining conformance.

   2. The tables are arranged to establish product screw thread acceptance criteria based on recognized gaging concepts used to assess conformance.

      1. Attributes. Fixed limit inspection/evaluation provides a qualitative assessment of a characteristic(s) using gages which determine conformance.

      2. Variables. Indicating control is a quantitative and qualitative assessment on a characteristic(s) which is then compared with limiting values in order to deter- mine if the characteristic(s) is in conformance.

         
         

4. GAGING SYSTEMS

   1. Tables 3 and 4 present screw thread gaging sys- tems for inspection/evaluation of externally and inter- nally threaded products, respectively.

   2. Three gaging systems for inspection/evaluation of threads on threaded products are established herein to provide a choice depending on the engineering requirement of the threaded product. These are identi- fied as Systems 21, 22, and 23. The difference between gaging systems is the level of inspection/evaluation deemed necessary to satisfy that conformance has been achieved.

   3. Since most screw thread applications do not require that all of the characteristics described in the

      
      

      1

      ASME B1.3-2007

      
      

      applicable product specifications, standards, and appli- cations documents be inspected/evaluated, selection of the appropriate gaging system will be based on those characteristics important to the end use. Consideration should be given to such factors as form, fit, function, and fabrication of the threaded product. Measurement/ gage design capabilities inherent in each inspection/ evaluation system should also be considered when com- paring the benefits of each system. Guidance for selec- tion of an inspection/evaluation system from the three established gaging systems is as follows:

      1. System 21. Provides for interchangeable assem- bly with functional size inspection/evaluation at the maximum material limit within the length of standard gaging elements, and also inspection/evaluation of characteristics identified as NOT GO functional diame- ters or as HI (internal) and LO (external) functional diameters.

      2. System 22. Provides for interchangeable assem- bly with functional size inspection/evaluation at the maximum material limit within the length of standard gaging elements, and also inspection/evaluation of the minimum material size pitch diameter or thread groove diameter over the length of the full thread. The cumula- tive effects of all other thread characteristics such as lead, flank angle, taper, and roundness variations are confined within product tolerance limits with no specific inspection/evaluation of their magnitudes.

      3. System 23. Provides for interchangeable assem- bly with functional size inspection/evaluation at the maximum material limit within the length of standard gaging elements, and also inspection/evaluation of the minimum material size pitch diameter or thread groove diameter over the length of the full thread. The magni- tude of other thread characteristics such as lead, flank angle, taper, and roundness are further inspected/evalu- ated, as specified within the pitch diameter limits. Only thread characteristics in System 23 for which require- ments or limitations are specified must be inspected/ evaluated for System 23 compliance. For example, if the product thread has no surface texture requirement nor major-to-pitch runout limitation, then System 23 does not require that these two characteristics be checked.

   4. For special applications, the screw thread on a threaded product may require inspection/evaluation not consistent with any of the standard gaging systems. In such cases, one of the standard gaging systems should be selected and modified by specifying, in accordance with para. 7(b), the addition or the reduction of thread characteristic(s) and gage(s) as selected from Table 1 or 2, as applicable.

   5. Product threads affected by roundness variations may be even-lobed (180 deg contact) or odd-lobed (120 deg contact). Product thread acceptance or rejection can be influenced by thread gages and measuring equip- ment having the ability to detect one, but not both,

      because of gage design. Tables 1 and 2 provide a selection of gages which in combination may be needed to assure that diameter size variations caused by out-of-round- ness are contained within product tolerance limits.

      
      

5. GAGING REQUIREMENTS

   1. Screw threads of threaded products are defined by the applicable thread document. Appropriate standards are listed in section 2.

   2. The gaging system used to inspect/evaluate the screw thread of a threaded product shall be as specified in the product standard, procurement drawing, or pur- chase inquiry and order. In the absence of a specified gaging system on the purchase order, product drawing, or other applicable documentation, the supplier and cus- tomer must agree upon a suitable gaging system. There is no implied default gaging system.

   3. Each of the thread characteristics specified in the gaging system shall be inspected/evaluated using the gage (or one of the gages) specified for that characteris- tic. Gages shall be in conformance with the applicable gaging documents. Use appropriate standards listed in section 2 unless otherwise specified.

   4. The use of any gage or measuring device is not precluded if the results given by such gage or measuring device correlate with a gage or measuring device listed in this Standard.

   5. All measurement results are not necessarily equal to a characteristic’s true size. The environment, the instruments, and the operator are factors influencing measurement results. The sum of these factors may be cumulative, making the measurement results further from the characteristic’s true size, or the factors may cancel each other out, making the measurement results closer to the characteristic’s true size.

      
      

6. ACCEPTABILITY

   1. The screw thread of a threaded product shall be acceptable when each of the thread characteristics speci- fied in the designated gaging system is found to be acceptable.

   2. Within each gaging system, a choice of gages is specified for each characteristic. Acceptance by any one gage in current calibration specified for a characteristic shall be the criterion for acceptance of that characteristic.

   3. All threaded products are subject to visual inspec- tion/evaluation for gross defects. This visual inspec- tion/evaluation shall be made without magnification and is intended to detect such gross defects as missing or incomplete threads, defective thread profile, torn or ruptured surfaces and cracks, etc. Surface texture of threaded products, when required, will be inspected/ evaluated by visual or tactile comparison with texture specimens or surface measurement equipment. ASME B46.1 provides roughness average (Ra) guidelines

2