1、AMERICAN NATIONAL STANDARD DryseaI Pipe Threads (Inch) ANSI B1.20.3 - 1976 (REVISION AND REDESIGNATION OF 82.2-1968) REAFFIRMED 1998 FOR CURRENT COMMllTEE PERSONNEL PLEASE SEE ASME MANUAL AS-I 1 SECRETARIAT SOCIETY OF AUTOMOTIVE ENGINEERS THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS PUBLISHED BY THE
2、 AMERICAN SOCIETY OF MECHANICAL ENGINEERS United Engineering Center 345 East 47th Street New York, N. Y. 1001 7 ANSI 81.20.3-1976 31 October 1980 ACCEPTANCE NOTICE The above non-Government document was adopted (with exception listed below) on31 1980and is approved for use by the Federal agencies. Th
3、e indicated industry group has furnished the Clearance required by exfsting regulations. Copies of the document are stocked by the 000 Single Stock Point, Naval Publications and Forms Center, Philadelphia, PA 19120, for issue to DoD activities only. Contractors and industry groups must obtain copies
4、 directly from: The American Society of Mechanical Engineers New York. NY 10017 or United Engineering Center, 345 East 47th Street, The American National Standards Institute, 1430 Broadway, New York. NY 10018. Title of Document: Dryseal Pipe Threads (Inch) Date of Specific Issue Adopted: 18 November
5、 1976 Releasing Industry Group: The American Society of Mechanical Engineers Exception: The Federal agencies use of this Standard is subject to all the requirements and limitations of FED-STD-H28/8 - Screw-Thread Standards for Federal Services Section 8, Dryseal Pipe Threads. Military Custodians: Ar
6、my - AR Navy - AS Air Force - 11 Review Activities: Army - AT, AV, ER, ME, MI Navy - OS, SH. YD civil Agency Coordinating Activities: Comnerce - NBS DOT - ACO, FHW. FIS. FRA, ROS GSA - FSS. PCD HUO - TCS Interior - 8PA Justice - FPI NASA - JFK, LRC, MSF USOA - AFS Military Coordinating Activity: OLA
7、- I S (Project THCS-0034) NOTICE: When reaffirmation. amendment, revision, or cancellation of this standard is initially proposed, the industry group responsible for this standard shall inform the military coordinating activity of the proposed change and request their participation. AREA THOS No par
8、t of this document may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher. Copyright 0 1977 by THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS All Rights Reserved Printed in USA. FOREWORD In 1913 a Committee on the Standardiz
9、ation of Pipe Threads was organized for the purpose of re- editing and expanding the Briggs Standard. The American Gas Association and The American Society of Mechanical Engineers served as joint sponsors. After six years of work, this committee completed the revised standard for taper pipe thread w
10、hich was published in the ASME “Transactions” of 1919, and was approved as an American Standard by the then American Engineering Standards Committee (later changed to American Standards Association) in December, 1919. It was the first standard to receive this designation under the ASA procedure, and
11、 was later republished in pamphlet form. In the years which followed, the need for a further revision of this American Standard becameevident as well as the necessity of adding to it the recent developments in pipe threading practice. Accordingly, the Sectional Committee on the Standardization of Pi
12、pe Threads, B2, was organized in 1927 under the joint sponsorship of the A.G.A. and the ASME. During the following 15 years, several meetings were held leading to approval by the members of the Sectional Committee, of the April 1941 draft. The revision was approved by the sponsors and ASA and publis
13、hed as an American Standard in October 1942. Shortly after publication of the 1942 standard, the Committee undertook preparation of a complete revision. The text and tables were re-arranged and expanded to include Dryseal pipe threads, and an exten- sive appendix was added to provide additional data
14、 on the application of pipe threads and to record in abbreviated form the several special methods which were established for gaging some of the various applica- tions of pipe threads. The resulting proposal was designated an American Standard on December 11, 1945. The section covering Dryseal Pipe T
15、hreads in ASA B2.1-1945 was deleted and developed as a separate standard desig- nated ASA B2.2-1960, Dryseal Pipe Threads. Another updating occurred with republication as USAS B2.2- 1968. In 1973, Standards Committee B2 was absorbed by American National Standards Institute Standard Committee B1 and
16、reorganized as subcommittee 20. A complete rewrite of the B2.2-1968 document was undertaken with the product thread data in separate documents from the gaging standards for Dryseal Pipe threads. The system of renumbering, to include metric revisions, is as follows: ANSI B1.20.3-1976 Inch Dryseal Pip
17、e Threads ANSI B1.20.4-1976 Metric Dryseal Pipe Threads ANSI B1.20.5-197 Gaging for Inch Dryseal Pipe Threads ANSI B1.20.6-197 Gaging for Metric Dryseal Pipe Threads Since the product thread documents are being published before completion of the new gaging stan- dards, the ,gaging data in the B2.2-1
18、968 Standard should be used until superseded by publication of the new B 1.20.5 and B 1.20.6 gaging standards. ANSI B 1.20.3 and B 1.20.4 were approved by ANSI Committee B 1 for publication as official ANSI Standards and thereupon submitted to the Secretariat and the American National Standards Inst
19、itute. They were approved and formally designated as American National Standards on November 18, 1976. iii Intentionally left blank AMERICAN NATIONAL STANDARDS COMMITTEE 61 Standardization and Unification of Screw Threads (The following is the roster of the Committee at the time of approval of this
20、standard) Organized. June, 1921 Reorganized. February, 1929 SPONSORS: Society of Automotive Engineers The American Society of Mechanical Engineers SCOPE: Nomenclature of screw threads; form of threads; diameter and pitches of screws for various uses; classification of thread fits, tolerances and all
21、owances for threaded parts; and the gaging of threads. Screw threads for fire hose couplings are not included within the scope. T. C. Baumgartner, Chairman J. B. Levy, Vice-chairman S. W. Taylor, Secretary AEROSPACE INDUSTRIES ASSOCIATION OF AMERICA, INC. Propulsion Technical Committee D. H. Secord,
22、 Pratt Class 1 and Class 2. The classes differ only in inspection requirements, with Class 1 threads exactly those standardized in ANSI B2.2-1968 (in- spection of root and crest truncation not specified). Class 2 threads are identical to Class 1 threads except that inspection of root and crest trunc
23、ation is re- quired. For Class 2 threads, direct measurement of crest and root truncation is the referee method. These classes do not apply to other than NPTF Dryseal pipe threads. 1.1.7 All dimensions in this standard including all tables are in inches unless otherwise noted. NOCLEARANCE (BASIC) 1.
24、2 Thread Types External Dryseal pipe threads are tapered only. In- ternal Dryseal pipe threads may be either straight or tapered, as specified. Also, thread lengths may be either “standard” or “short,” depending on the re- quirements of the application. The short external thread is obtained by short
25、ening the standard thread by one pitch at the small end. A short internal taper thread is obtained by shortening the standard thread by one pitch at the large end. Accordingly, there are four standard types of Dryseal pipe threads, as follows: Type 1 - Dryseal USA (American) Standard Taper Type 2 -
26、Dryseal SAE Short Taper Pipe Thread, Type 3 - Dryseal USA (American) Standard Fuel Internal Straight Pipe Thread, NPSF Type 4 - Dryseal USA (American) Standard Inter- mediate Internal Straight Pipe Thread, NPSI Pipe Thread, NPTF PTE-SAE SHORT MAXIMUM INTERFERENCE NO CLEARANCE (BASIC) MAXIMUM INTERFE
27、RENCE cation so as to assure metal to metal contact at these points coincident with flank contact. This condition is established at The minimum material condition as shown at the left is established by having the mating crests and roots of equal trun- the sharpest root and the flattest crest and giv
28、es no clearance. Tolerances at the crests and roots are established in the direction of interference only, therefore the maximum material condition shown at the right is established by having the extreme combination of sharpest crests and flattest roots, which provide the maximum interference. NOTE:
29、 When threaded joints are made up wrenchtight, it is intended that the flanks and the crests and roots shall be in contact. FIG 1 EXTREME MATING CONDITIONS FOR DRYSEAL PIPE THREADS 2 AMERICAN NATIONAL STANDARD INCH DRYSEAL PIPE THREADS 1.3 Thread Deskpations and Notation The above types of Dryseal p
30、ipe threads are desig- nated by specitying in sequence the nominal size designations, thread series symbol, and class, as follows: /a -27 NPTF- 1 /a -27 NPTF-2 /8-27 PTF-SAE SHORT /8-27 NPSF /a -27 NPSI Each of the letters in the symbols has a definite N = National (American) Standard P = Pipe T = T
31、aper S = Straight F = Fuel and Oil I = Intermediate significance as follows: 1.3.1 NPTF Thread Class. Two classes of NPTF threads have been established: Class 1 and Class 2. Class 1 signifies that specific inspection of root and crest truncation is not required, while class 2 signifies that such is
32、required. Since class notation is introduced in this standard there will undoubtedly be a long period of time be- fore users completely adopt the new classification. In cases where class is not denoted, the thread shall be considered Class 1. 1.3.2 Designation of Plated Threads. The product specific
33、ations of this standard do not include an allow- ance for plating. If plating is desired, it may be neces- sary to modify the threads since the same final gaging requirements must be satisfied for plated and un- plated parts. This may be emphasized by adding the words AFTER PLATING to the designatio
34、n. For manufacturing purposes, notes for plated taper pipe threads may specify the gage limits (turns engagement) before plating followed by the words “BEFORE PLATING.“ These should be followed by the stan- dard gage limits (turns engagement) after plating and the words “AFTER PLATING.“ Examples of
35、optional designations for an external thread having 0.0002 inch plating thickness are: 3/8-18 NPTF-1, or /a -1 8 NPTF-I AFTER PLATING, or /a -1 8 NPTF-I , L I RING GAGE LIMITS 2% to 4% turns engagement before plating 2% to 4% turns engagement after plating /a -1 8 NPTF-I, L2 RING GAGE LIMITS .2?4 to
36、 3% turns beyond actual L, gage tllrn!: en- gagement before and after plating. ANSI 01.20.3-1976 Example of optional designations for internal thread with 0.0002 inch plating thickness is: y8-18 NPTF-1,or 3/-18 NPTF-1 AFTER PLATING, or /8 -18 NPTF-1, L 1 PLUG GAGE LIMITS 3 to 4% turns engagement bef
37、ore plating 2% to 4% turns engagement after plating 2% to 3% turns beyond actual L1 gage turns en- /a -1 8 NPTF- 1, L 3 PLUG GAGE LIMITS gagement before and after plating. 1.4 Applications 1.4.1 Type 1.4.1.7 NPTF. This type applies to both external and internal threads and is suitable for pipe joint
38、s in practically every type of service. Of all Dryseal pipe threads, NPTF external and internal threads mated are generally conceded to be superior for strength and seal since they have the longest length of thread and theoretically, interference (sealing) occurs at every en- gaged thread root and c
39、rest. Use of tapered internal threads, such as NPTF or PTF-SAE SHORT in hard or brittle materials having thin sections will minimize the possibility of fracture. 1.4.1.2 PTF-SA Short. External threads of this type conform in all respects with NPTF threads, ex- cept that the thread length has been sh
40、ortened by eliminating one thread from the small (entering) end. These threads are designed for applications where clearance is not sufficient for the full thread length of NPTF threads or for economy of material, where the full thread length, is not necessary. PTF-SAE SHORT external threads are int
41、ended for assembly with NPSI threads, but may also be assembled with NPTF in- ternal threads. They are not designed for and at ex- treme tolerance limits may not assemble with PTF- SAE SHORT internal or NPSF threads. Internal threads of this type conform in all respects with NPTF threads, except tha
42、t the thread length has been shortened by eliminating one thread from the large (entry) end. These threads are designed for thin materials where thickness is not sufficient for the full thread length of NPTF threads or for economy in tap- ping where the full thread length is not necessary. PTF-SAE S
43、HORT internal threads are primarily in- tended for assembly with NPTF external threads. They are not designed for and at the extreme tolerance limits may not assemble with PTF-SAE SHORT ex- ternal threads. Pressure-tight joints without the use of lubricant or sealer can best be assured where mating
44、corn- ponents are both threaded with NPTF threads. This 3 AMERICAN NATIONAL STANDARD INCH DRYSEAL PIPE THREADS ANSI 61.20.3-1976 should be considered before specifying PTF-SAE SHORT external or internal threads. 1.4.7.3 NPSF. Threads of this type are straight (cylindrical) instead of tapered and int
45、ernal only. They are more economical to produce than tapered internal threads, but when assembled do not offer as strong a guarantee of sealing since root and crest in- terference will not occur for all threads. NPSF threads are generally used with soft or ductile materials which will tend to adjust
46、 at assembly to the taper of external threads, but may be used in hard or brittle materials where the section is thick. They are primarily intended fnrbly with NPTF external threads. (For other applications see Appendix C.) 7.4.7.4 NPSI. Threads of this type are straight (cylindrical) instead of tap
47、ered, internal only, and are slightly larger in diameter than NPSF threads but have the same tolerance and thread length. They are more economical to produce than tapered threads and may be used in hard or brittle materials where the section is thick or where there is little expansion at assembly wi
48、th external taper threads. As with NPSF threads, NPSI threads when assembled do not offer as strong a guarantee of sealing as do tapered in- ternal threads. NPSI threads are primarily intended for assembly with PTF-SAE SHORT external threads, but can be used with NPTF external threads. 1.4.2 Class 7
49、.4.2.7 NPTF Class 1. Threads made to this class are designed to interfere (seal) at root and crest when mated, but inspection of crest and root truncation for acceptance is not required. Consequently, Class 1 threads are intended for applications where close con- trol of tooling is required for conformance of trunca- tion or where sealing is accomplished by means of a sealant applied to the threads. 7.4.2.2 NPTF Class 2. Threads made to this class are theoretically identical to those made to Class 1, howeve: inspection of root and crest truncation is re- quired. Consequently, where
