1、AN AMERICAN NATIONAL STANDARD ASME B1.20.1-2013Revision of ASME B1.20.1-1983 (R2006)Pipe Threads, General Purpose (Inch)ASME B1.20.1-2013Revision of ASME B1.20.1-1983 (R2006)Pipe Threads,General Purpose(Inch)AN AMERICAN NATIONAL STANDARDTwo Park Avenue New York, NY 10016 USADate of Issuance: Novembe
2、r 15, 2013This Standard will be revised when the Society approves the issuance of a new edition. There willbe no written interpretations of the requirements of this Standard issued to this edition.Periodically certain actions of the ASME B1 Committee may be published as Cases. Cases are publishedon
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10、 retrieval system or otherwise,without the prior written permission of the publisher.The American Society of Mechanical EngineersTwo Park Avenue, New York, NY 10016-5990Copyright 2013 byTHE AMERICAN SOCIETY OF MECHANICAL ENGINEERSAll rights reservedPrinted in U.S.A.CONTENTSForeword ivCommittee Roste
11、r . vCorrespondence With the B1 Committee vi1 Introduction . 12 American National Standard Pipe Thread Form . 23 Specification for Taper Pipe Threads, NPT . 44 Specifications for Internal Straight Threads in Pipe Couplings, NPSC 135 Specifications for Railing Joint Taper Pipe Threads, NPTR . 146 Spe
12、cifications for Straight Pipe Threads for Mechanical Joints; NPSM, NPSL . 167 Gages and Gage Tolerances for American National Standard Taper PipeThreads, NPT 19Figures1 Root, Crest, and Flank Engagement, NPT . 22 Basic Form of American National Standard Taper Pipe Thread, NPT . 33 American National
13、Standard Taper Pipe Thread Notation 64 Gaging External Taper Threads With L1Ring Gage 105 Gaging of Chamfered Threads 116 Gaging Internal Taper Threads With L1Plug Gage . 127 NPT Standard Taper Pipe Thread Plug and Ring Gages 208 Suggested Form of Gage Thread 21Tables1 Limits on Crest and Root Trunc
14、ation of American National Standard Externaland Internal Taper Pipe Threads, NPT 52 Basic Dimensions of American National Standard Taper Pipe Thread, NPT . 83 Tolerances on Taper, Lead, and Angle of Pipe Threads, NPT . 104 Dimensions, Internal Straight Threads in Pipe Coupling, NPSC 145 Dimensions o
15、f External and Internal Taper Pipe Threads for RailingJoints, NPTR . 156 Dimensions of External and Internal Straight Pipe Threads for Fixtures, NPSM . 177 Dimensions, External and Internal Straight Pipe Thread for LocknutConnections, NPSL . 188 Basic Dimensions of Threaded Gages for American Nation
16、al Standard Taper PipeThreads, NPT 229 Working Gage Tolerances for American National Standard Taper PipeThread, NPT . 2310 Diameter Equivalent of Variation in Half Included Angle of Thread for Toolsand Gages . 2511 Diameter Equivalent of Variation in Lead for Tools and Gages . 26Nonmandatory Appendi
17、cesA The Turns of Engagement Method of Gaging Product Threads . 27B Tap Drill Sizes 28C Thread Types and Corresponding Gages and Gaging 29iiiFOREWORDIn 1973, American National Standards Committee B2, which had formerly been responsible forpipe thread standards, was absorbed by American National Stan
18、dards Institute (ANSI) StandardsCommittee B1 and reorganized as Subcommittee 20. A complete rewrite of the B2.1-1968 standardon Pipe Threads (Except Dryseal) was undertaken. It was approved and formally designated asan American National Standard on February 4, 1983 and was reaffirmed in 2001 and 200
19、6. Thesystem of numbering, to include metric conversions, is as follows:ANSI/ASME B1.20.1, Pipe Threads, General Purpose (Inch)ASME B1.20.2M-2006, Pipe Threads, 60, General Purpose (Metric Translation)These standards, ANSI/ASME B1.20.1 and B1.20.2M, have product thread dimensions andgaging in the sa
20、me document. Thread inspection specifies the use of L1taper thread gages similarto B2.l-1968. In addition, emphasis was given to the requirement that all basic thread designdimensions were to be met within the specified tolerances.This revision of ANSI/ASME B1.20.1 has both significant and subtle su
21、bstantive changes tothe 1983 revision. It is more explanatory for the user than the previous revision. Significantchanges are as follows:(a) An acceptability section has been added, providing a referee method in cases of dispute.This acknowledges the potentially wide but acceptable variation in the
22、prescribed gages andgaging methods.(b) Figures have been updated with additional information and drawn to be more visuallyexplanatory.(c) The Turns of Engagement method has been moved to an appendix, due to its inherent gagecorrelation issues. This gaging method may be used when parties agree, but i
23、t is no longer anaccepted method within the Standard.(d) Calculated data have been revised following the rounding rules of B1.30M. This providesa standardized high level of precision in calculation. Some tabulated values changed, but nochanges were deemed significant enough to affect the conformance
24、 status of products or gages.These changes are generally beyond the margin of error of the required measurements. NPTR,NPSM, and NPSL thread dimensions were not recalculated as some historical methodology,necessary for computation, was not available.(e) Guidance for tap drill sizes has been updated
25、to reflect varying manufacturing conditionsand the wider range of available drill sizes. Instead of specifying drill sizes, the Standard nowrefers to the tabulated basic minor diameter of the internal thread as a reference in which to basedrill size choice.(f) Added are detailed explanations on the
26、effects of coatings on threads, as well as guidancefor precoating size compensation.(g) The gaging point of reference is moved for external threads having chamfer diameterssmaller than the minor diameter at the small end. This change was made to help ensure adequatethread engagement over a wider ran
27、ge of product thread chamfers. This change is correspondentto the existing treatment of chamfers for internal threads.(h) The point of reference for checking wear on working gages is changed to basic. Previously,the point of reference was the size at the time of manufacture. This change facilitates
28、the calibrationof gages when the original size at manufacture is not known and standardizes gage sizes atmaximum wear.(i) Gaging guidance for straight pipe threads has been expanded, including allowing the No-Go to enter up to three turns, mimicking ASME B1.2.(j) The use of indicating gages has been
29、 added as a gaging method.Following the approvals of the Standards Committee and ASME, approval for the new editionwas granted by ANSI on October 15, 2013.All requests for interpretation or suggestions for revisions should be sent to the Secretary,B1 Committee, The American Society of Mechanical Eng
30、ineers, Two Park Avenue, New York,NY 10016-5990.ivASME B1 COMMITTEEStandardization and Unification of Screw Threads(The following is the roster of the Committee at the time of approval of this Standard.)STANDARDS COMMITTEE OFFICERSA. L. Barrows, ChairD. S. George, Vice ChairA. L. Guzman, SecretaryST
31、ANDARDS COMMITTEE PERSONNELA. L. Barrows, Swanson Tool Manufacturing, Inc.K. Bly, Vermont Thread GageG. A. Cuccio, Capitol Manufacturing Co.R. Dodge, Pennoyer Dodge Co.D. Everrett, National Institute of Standards Order Department: 22 Law Drive, P.O.Box 2900, Fairfield, NJ 07007-2900 (www.asme.org)1.
32、7 TerminologyDefinitions of terms and symbols for thread dimen-sions are given in ASME B1.7.22 AMERICAN NATIONAL STANDARD PIPE THREADFORM2.1 Thread FormThe form of thread profile specified in this Standardshall be known as the American National Standard PipeThread Form (see Fig. 2).2.2 Angle of Thre
33、adThe angle between the sides of the thread is 60 degwhen measured in an axial plane. The line bisecting thisangle is perpendicular to the axis.2.3 Thread HeightThe height of the sharp V thread, H,isH p 0.86602540PwhereP p pitch of threadASME B1.20.1-2013Fig. 2 Basic Form of American National Standa
34、rd Taper Pipe Thread, NPTExternal Thread Internal ThreadAxis90 deg 90 deg60 deg90 deg 90 degCrestRootFrsfrshHFcsfcsfcnFcnCrestRootPfrnFrn90 deg3ASME B1.20.1-2013For a symmetrical straight screw thread with a 30-degflank angle, Hpcot H9251/2np0.86602540P. For a symmet-rical taper screw thread with a
35、30-deg flank angle anddiametral taper of 0.750 in./ft, H p (cot H9251 tan2H9252 tanH9251)/2n p 0.86574320P. For an 8-pitch thread, which isthe coarsest standard taper pipe thread pitch, the corres-ponding values of H are 0.1082179 and 0.1082532, respec-tively. The difference of 0.000035 in. being in
36、significant,the value of H p 0.86602540P is used for all straightand tapered threads in this Standard.2.4 Thread TruncationThe maximum height of the truncated thread, h (seeFig. 2), is based on factors entering into the manufactureof cutting tools and the making of tight joints.h p 0.800PThe crest a
37、nd root of pipe threads are truncated aminimum of 0.033P. The maximum depth of truncationfor the crest and root of these pipe threads will be foundin Table 1. The crests and roots of the external and inter-nal threads may be truncated either parallel to the pitchline or parallel to the axis. The ill
38、ustration in Table 1,giving a sectional view of this Standard thread form,represents the truncated thread form by a straight lineand sharp corners. However, a radius form is acceptable,as long as the crests and roots lie within the limits shownin Table 1. Some of the truncations in this illustration
39、are shown with dotted lines as radii.3 SPECIFICATION FOR TAPER PIPE THREADS, NPT3.1 GeneralNPT joints made in accordance with these specifica-tions consist of an external taper and internal taperthread (see Figs. 1 through 3). NPT taper pipe threadsare intended to be made up wrench-tight and with as
40、ealant when a pressure-tight joint is required.3.1.1 Notation. The standard notation applicableto the American National Standard Taper Pipe Thread,NPT, is shown in Fig. 3.3.1.2 Symbols. The following symbols are specificto this Standard:D p outside diameter of pipeE0p basic pitch diameter at small e
41、nd of externalthread (or end of pipe)E1p basic pitch diameter at plane of hand-tightengagement length (L1), external thread, andlarge end of internal threadE2p basic pitch diameter at plane of effectivethread length (L2), external threadE3p basic pitch diameter at plane of wrench-tightengagementE5p
42、basic pitch diameter pipe at L5, plane of com-plete thread length4K0p basic minor diameter at small end of externalthread (or end of pipe)L1p length of hand-tight engagement betweeninternal and external threadsL2p length of effective thread, external thread.Equal to L1plus wrench make-up threadsL3p
43、length of thread beyond L1allowing wrench-tight engagement, internal thread (also,wrench make-up)L4p overall length of thread, including vanishthread, external threadL5p length of complete threads, external thread,where cone of major diameter intersects out-side diameter of pipeV p length of vanish
44、threads3.1.3 Handling Considerations. The potential effectson thread form and gaging must be considered whenchoosing coatings and other processes. Some processes,such as barrel coating, can be damaging to the threadform, especially the crests of external threads. See para.3.2.3 on gaging nicked thre
45、ads.3.1.4 Form of Thread. The form of the thread isspecified in para. 2.1.3.1.5 Taper of Thread. The basic taper of the threadis 1 in 16 or 0.75 in./ft measured diametrically relativeto the axis.3.1.6 Pitch Diameters of Thread. The basic pitchdiameters of the tapered thread are determined by thefoll
46、owing formulas based on the outside diameter of thepipe and the pitch of the thread:E0p D (0.05D + 1.1) 1/np D (0.05D + 1.1)PE1p E0+ 0.0625 L1whereD p outside diameter of pipeE0p pitch diameter of thread at end of pipe orsmall end of external threadE1p pitch diameter of thread at the large end ofint
47、ernal threadL1p hand-tight length of engagement betweenexternal and internal threads, also the hand-tight length of thread for both internal andexternal threadsn p threads per inch3.1.7 Length of Effective Thread. The basic lengthof the effective external taper thread L2, is determinedby the followi
48、ng formula based on the outside diameterof the pipe and the pitch of the thread:L2p (0.80D + 6.8)1/np (0.80D + 6.8)PwhereD p outside diameter of pipen p threads per inchASME B1.20.1-2013Table 1 Limits on Crest and Root Truncation of American National Standard External andInternal Taper Pipe Threads,
49、 NPTMinimum truncationMaximum truncationMinimum truncationMaximum truncationExternal ThreadInternal ThreadRootCrestCrestRootCrestMinimum truncationMaximum truncationMinimum truncationMaximum truncationMax. hHTruncation, f Equivalent Width of Flat, FHeight of Thread,Height ofh Min. Max. Min. Max.Threads/ Sharp VInch, n Thread, H Min. Max. Formula in. Formula in. Tolerance Formula in. Formula in. Tolerance1 2 3 4 5678 9 10112131427 0.0320750 0.02496 0.02963 0.033P 0.0012 0.096P 0.0036 0.0024 0.038P 0.0014 0.111P 0.0041 0.002718 0.0481125 0.03833 0.04444 0.033P 0.0018 0.088P 0.0
