1、AN AMERICAN NATIONAL STANDARD ASME B16.25-2012(Revision of ASME B16.25-2007)Buttwelding EndsASME B16.25-2012(Revision of ASME B16.25-2007)ButtweldingEndsAN AMERICAN NATIONAL STANDARDThree Park Avenue New York, NY 10016 USADate of Issuance: December 20, 2012The next edition of this Standard is schedu
2、led for publication in 2017.ASME issues written replies to inquiries concerning interpretations of technical aspects of thisStandard. Periodically certain actions of the ASME B16 Committee may be published as Cases.Cases and interpretations are published on the ASME Web site under the Committee Page
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11、 Park Avenue, New York, NY 10016-5990Copyright 2012 byTHE AMERICAN SOCIETY OF MECHANICAL ENGINEERSAll rights reservedPrinted in U.S.A.CONTENTSForeword ivCommittee Roster . vCorrespondence With the B16 Committee viSummary of Changes vii1 Scope 12 Transition Contours . 13 Welding Bevel Design . 24 Pre
12、paration of Inside Diameter of Welding End 25 Tolerances 3Figures1 Maximum Envelope for Welding End Transitions . 42 Bevels for Wall Thickness Over 3 mm (0.12 in.) to 22 mm (0.88 in.), Inclusive 53 Weld Bevel Details for Wall Thickness Over 22 mm (0.88 in.) 64 Weld Bevel Details for GTAW Root Pass W
13、all Thickness Over3 mm (0.12 in.) to 10 mm (0.38 in.), Inclusive 75 Weld Bevel Details for GTAW Root Pass Wall Thickness Over10 mm (0.38 in.) to 25 mm (1.0 in.), Inclusive 76 Weld Bevel Details for GTAW Root Pass Wall Thickness Over25 mm (1.0 in.) 8Table1 Dimensions of Welding Ends . 9Mandatory Appe
14、ndicesI Inch Table . 13II References . 18Nonmandatory AppendixA Quality System Program . 19iiiFOREWORDIn July 1953, the American Welding Society presented a proposal on Welding End Preparationto Sectional Committee B16 of the American Standards Association (ASA), with the recommenda-tion that it be
15、considered as a candidate for an American Standard. The proposal was expandedto include welding preparation for flanges and valves covered by ASA B16.5, Steel Pipe Flangesand Flanged Fittings, and for fittings covered by ASA B16.9, Buttwelding Fittings. Considerationwas also given to Pipe Fabricatio
16、n Institute Standard ES-1.The third draft reviewed by Subcommittee 3, Subgroup 6 (now Subcommittee F), of theB16 Sectional Committee was forwarded to the Committee, cosponsor organizations, and thenASA for approval. Final approval was given on September 14, 1955, with the designationASA B16.25-1955.
17、Revisions were developed as a need for clarification and improvements became known andwere approved as ASA B16.25-1958 and ASA B16.25-1964. After ASA reorganized as the AmericanNational Standards Institute (ANSI) and the Sectional Committee became American NationalStandards Committee B16, a further
18、revision was approved as ANSI B16.25-1972.Subcommittee F immediately began work on a major expansion and updating of the Standard,adding illustrations and requirements for welding end configurations applicable to a number ofspecific circumstances, including cast steel and alloy valves. When a draft
19、had been developed thatovercame the many problems and conflicting demands, the Standards Committee, cosecretariatorganizations, and ANSI concurred in approval of ANSI B16.25-1979 on July 18, 1979.In 1982, American National Standards Committee B16 was reorganized as an ASME committeeoperating under p
20、rocedures accredited by ANSI. In the 1986 edition, inch dimensions wereestablished as the standard, and numerous changes in text and format were made. Notes forillustrations were also clarified. Following approval by the Standards Committee and ASME,approval as an American National Standard was give
21、n by ANSI on October 8, 1986, with thenew designation ASME/ANSI B16.25-1986.In 1992, the subcommittee revised the requirements for the preparation of the inside diameterof welding end. The references in Annex B were also updated. After public review and approvalby ASME, this edition was approved by
22、ANSI on October 26, 1992, with the new designationASME B16.25-1992.In the 1997 edition, metric dimensions were added as an independent but equal standard tothe inch units. An Annex was also added to reference quality system requirements. Followingapproval by the Standards Committee and ASME, this re
23、vision to the 1992 edition of B16.25 wasapproved as an American National Standard by ANSI on April 17, 1997, with the new designationASME B16.25-1997.In the 2003 edition, the reference standard dates were updated. There were clarifications totext made to address inquiries. Tolerances on bevel angles
24、 were modified slightly. Followingapproval by the Standards Committee and ASME, this revision to the 1997 edition of B16.25 wasapproved as an American National Standard by ANSI on December 17, 2003, with the newdesignation ASME B16.25-2003.In the 2007 edition, buttwelding end data were extended to c
25、over requirements for sizes upto NPS 48 (DN 1200). The reference data were updated, and the interpretation section wasremoved from the Standard.In this 2012 edition, the references in Mandatory Appendix II have been updated, and noteshave been updated in the included tables. This revision was approv
26、ed by ANSI on October 22, 2012.Requests for interpretation or suggestions for revision should be sent to the Secretary, B16Committee, The American Society of Mechanical Engineers, Three Park Avenue, New York, NY10016-5990.ivASME B16 COMMITTEEStandardization of Valves, Flanges, Fittings, and Gaskets(
27、The following is the roster of the Committee at the time of approval of this Standard.)STANDARDS COMMITTEE OFFICERSW. B. Bedesem, ChairG. A. Jolly, Vice ChairC. E. OBrien, SecretarySTANDARDS COMMITTEE PERSONNELA. Appleton, Alloy Stainless Products Co., Inc.R. W. Barnes, ANRIC Enterprises, Inc.W. B.
28、Bedesem, ConsultantR. M. Bojarczuk, ExxonMobil Research however, they shouldnot contain proprietary names or information.Requests that are not in this format will be rewritten in this format by the Committee priorto being answered, which may inadvertently change the intent of the original request.AS
29、ME procedures provide for reconsideration of any interpretation when or if additionalinformation that might affect an interpretation is available. Further, persons aggrieved by aninterpretation may appeal to the cognizant ASME Committee or Subcommittee. ASME does not“approve,” “certify,” “rate,” or
30、“endorse” any item, construction, proprietary device, or activity.Attending Committee Meetings. The B16 Standards Committee regularly holds meetings, whichare open to the public. Persons wishing to attend any meeting should contact the Secretary ofthe B16 Standards Committee.viASME B16.25-2012SUMMAR
31、Y OF CHANGESFollowing approval by the ASME B16 Committee and ASME, and after public review,ASME B16.25-2012 was approved by the American National Standards Institute onOctober 22, 2012.ASME B16.25-2012 includes the following changes identified by a margin note, (12).Page Location Change9 Table 1 Not
32、e (2) added14 Table I-1 Note (2) added18 Mandatory Appendix II UpdatedviiINTENTIONALLY LEFT BLANKviiiASME B16.25-2012BUTTWELDING ENDS1 SCOPE1.1 GeneralThis Standard covers the preparation of buttweldingends of piping components to be joined into a pipingsystem by welding. It includes requirements fo
33、r weldingbevels, for external and internal shaping of heavy-wallcomponents, and for preparation of internal ends(including dimensions and tolerances). Coverageincludes preparation for joints with the following:(a) no backing rings(b) split or noncontinuous backing rings(c) solid or continuous backin
34、g rings(d) consumable insert rings(e) gas tungsten arc welding (GTAW) of the root passDetails of preparation for any backing ring must bespecified when ordering the component.1.2 ApplicationThis Standard applies to any metallic materials forwhich a welding procedure can be satisfactorilyqualified bu
35、t does not prescribe specific welding pro-cesses or procedures. Unless otherwise specified by thepurchaser, it does not apply to welding ends conformingto ASME B16.5, B16.9, or B16.47.1.3 Relevant UnitsThis Standard states values in both SI (Metric) andU.S. Customary units. These systems of units ar
36、e to beregarded separately as standard. Within the text, theU.S. Customary units are shown in parentheses or in aseparate table that appears in Mandatory Appendix I.The values stated in each system are not exact equiva-lents; therefore, it is required that each system of unitsbe used independently o
37、f the other. Combining valuesfrom the two systems constitutes nonconformance withthe Standard.1.4 SizeNominal pipe size (NPS), followed by a dimensionlessnumber, is the designation for nominal fitting size. NPSis related to the reference nominal diameter (DN) usedin international standards. The rela
38、tionship is typicallyas follows:1NPS DN12153420125114321124025021265384 100For NPS 4, the related DNp25 H11547 NPS.1.5 Referenced StandardsStandards and specifications adopted by reference inthis Standard are shown in Mandatory Appendix II. Itis not considered practical to identify the specific edit
39、ionof each standard and specification in the individual ref-erences. Instead, the specific edition reference is identi-fied in Mandatory Appendix II. A product made inconformance with a prior edition of referenced stan-dards will be considered to be in conformance, eventhough the edition reference m
40、ay be changed in a subse-quent revision of the standard.1.6 Quality SystemsNonmandatory requirements relating to the manufac-turers quality system program are described inNonmandatory Appendix A.1.7 ConventionFor determining conformance with this Standard, theconvention for fixing significant digits
41、 where limits(maximum and minimum values) are specified shall beas defined in ASTM E29. This requires that an observedor calculated value be rounded off to the nearest unitin the last right-hand digit used for expressing the limit.Decimal values and tolerances do not imply a particularmethod of meas
42、urement.2 TRANSITION CONTOURSFigure 1 delineates the maximum envelope in whichtransitions from welding bevel to the outer surface ofthe component and from the root face to the inner surfaceof the component must lie. Except as specified in Note (5)to Fig. 1, and as otherwise specified by the purchase
43、r, theexact contour within this envelope is the manufacturersoption, provided it maintains the specified minimumASME B16.25-2012wall thickness, has no slopes steeper than those indi-cated for the respective regions, and includes the propersurface for backing rings if specified.3 WELDING BEVEL DESIGN
44、3.1 Bevels for Other Than GTAW Root Pass(a) Components having nominal wall thicknesses of3 mm (0.12 in.) and less shall have ends cut square orslightly chamfered.(b) Components having nominal wall thicknessesover 3 mm (0.12 in.) to 22 mm (0.88 in.) inclusive shallhave single angle bevels as illustra
45、ted in Fig. 2.(c) Components having nominal wall thicknessesgreater than 22 mm (0.88 in.) shall have compound anglebevels as illustrated in Fig. 3.3.2 Bevels for GTAW Root Pass(a) Components having nominal wall thicknesses of3 mm (0.12 in.) and less shall have ends cut square orslightly chamfered.(b
46、) Components having nominal wall thicknessesover 3 mm (0.12 in.) to 10 mm (0.38 in.) inclusive shallhave 3712-deg 212-deg bevels or slightly concave bevels(see Fig. 4).(c) Components having nominal wall thicknessesover 10 mm (0.38 in.) to 25 mm (1.0 in.) inclusive shallhave bevels as shown in Fig. 5
47、.(d) Components having nominal wall thicknessesgreater than 25 mm (1.0 in.) shall have bevels as shownin Fig. 6.3.3 Outside Diameter at Welding EndsDimension A shall be either that specified in theapplicable component standard or that specified in thepurchasers component specification. In the absenc
48、eof a requirement for dimension A in a component stan-dard or a purchasers specification, the values for dimen-sion A in Table 1 or Table I-1 may be used.4 PREPARATION OF INSIDE DIAMETER OFWELDING END4.1 GeneralPreparation of the inside diameter at the end of acomponent shall be in accordance with o
49、ne of the follow-ing, as specified by the purchaser:(a) Components to be welded without backing ringsshall meet the requirements of the standard or specifica-tion for the component.(b) Components to be welded using split or noncon-tinuous backing rings shall be contoured with a cylindri-cal surface at the end as shown in Fig. 2, illustration (b)and Fig. 3, illustration (b). If the backing ring contouris other than rectangular, details must be furnished bythe purchaser.2(c) Components to be welded using solid or continu-ous backing rings shall be contoured with a c
