1、AN AMERICAN NATIONAL STANDARDASME B31P-2017Standard Heat Treatments for Fabrication ProcessesASME Code for Pressure Piping, B31ASME B31P-201 7Standard HeatTreatments forFabricationProcessesASME Code for Pressure Piping, B31xDate of Issuance: May 15, 2018The next edition of this Standard is scheduled
2、 for publication in 2021.ASME issues writt en replies to inquiries concerning int erpretations of technical aspects of this Standard. Interpretations arepublished under http:/ /go.asme.org/Interpretations. Periodically certain actions of the ASME B31 Committ ees may bepublished as Cases. Cases are p
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11、y individuals.No part of this document may be reproduced in any form,in an electronic retrieval sys t em or otherwise,without the prior writ ten permission of the publisher .The American Society of Mechanical EngineersTwo Park Avenue, New York, NY 10016-5990Copyright 2018 byTHE AMERICAN SOCIETY OF M
12、ECHANICAL ENGINEERSAll rights reservedPrinted in U.S.A.CONTENTSForeword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vCommittee Roster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viCorrespondence With the B31 Committee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14、 . . . . . . . . . . . . . . . . . . . . . . 12 Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Temperature Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15、. . . . . . . 14 Temperature Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Welding Preheat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Postweld Heat T
16、reatment (PWHT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 Postforming and Material Heat Treatments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 Alternatives and Exemptions to Preheat and PWHT Requirements . . . .
17、. . . . . . . . . . . . . . . . . . 9Nonmandatory AppendicesA Recommendations for the Proper Use of Thermocouples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10B Recommendations for Control of Narrow Temperature Range Heat Treatments: Local Heat- TreatmentMethods . . . . . . . . . . .
18、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11C Branch Connection Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26D Temper Bead Method Alternative to PWHT . . . . . . . . . . . . .
19、. . . . . . . . . . . . . . . . . . . . . . . . . . 28E Fracture Mechanics Alternative to PWHT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29FiguresB-3.1-1 Definition of Terms for Local Circumferential Band Heating of Pipe Weld . . . . . . . . . . . . . . . . . 12
20、B-3.1-2 Definition of Terms for Local Circumferential Band Heating of Branch Connection to Pipe AttachmentWeld . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13B-5.2-1 Location of Thermocouples (Monitoring and Control
21、) for Pipe Sizes Less Than NPS 6 (150 DN) and OneControl Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15B-5.2-2 Location of Thermocouples (Monitoring and Control) for Pipe Sizes NPS 6 (DN 150) Up to andIncluding NPS 12 (DN
22、 300) and Two Control Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16B-5.2-3 Location of Thermocouples (Monitoring and Control) for Pipe Sizes NPS 14 (DN 350) Up to andIncluding NPS 30 (DN 750) and Four Control Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
23、17B-5.2-4 Location of Monitoring Thermocouples for Branch Nozzle or Attachment Welds . . . . . . . . . . . . 18B-5.3-1 Example of One Approach When the Heated Band From a Weld Requiring PWHT Intersects a Weld NotRequiring PWHT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
24、 . . . . . . . . . . . . . . . . . . . 20C-1 Typical Branch Attachment Details That May Be Used to Calculate Control Thickness . . . . . . . . 26C-2 Typical Integrally Reinforced Outlet Fitting Branch Connection Details That May Be Used to CalculateControl Thickness . . . . . . . . . . . . . . . . .
25、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27Tables5.1-1 Preheat Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36.1.1-1 Postweld Heat Treatment . . . . . . . . . . . . . . . . . . . . . . .
26、. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5iii6.1.1-2 Alternate Postweld Heat Treatment Requirements for Carbon and Low- Alloy Steels, P-Nos. 1 and 3 66.1.1-3 Exemptions to Mandatory Postweld Heat Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76.2-1 Approx
27、imate Lower Transformation Temperatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9B-5.1-1 Requirements for Control Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14FormsForm 1 Standard Procedure for Local Heating . . . . .
28、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22Form 2 Standard Documentation Checklist for Local Heating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25ivFOREWORDIn 2011, the B31 Standards Committee for Pressure Piping determined that more consisten
29、cy was needed between theB31 Code Sections regarding preheat and postweld heat treatment (PWHT) rules. The B31 Fabrication a proposal was developed, which was accepted by the B31 Standards Committee and the BPTCS.This Standard is intended to provide requirements for preheating and PWHT when mandated
30、 by the applicable CodeSection or by the engineering design being used. While the Code Sections provide only preheat and PWHT rules for ferrousmaterials, this Standard may provide expanded rules and alternatives for a wider variety of materials, although allmaterials that may be possible to use may
31、not be covered.Under direction of ASME Standards and Certification, both U.S. Customary and SI units are provided.Following approval by the B31 Committee and ASME, and after public review, ASME B31P-2017 was approved by theAmerican National Standards Institute on November 15, 2017.vASME B31 COMMITTE
32、ECode for Pressure Piping(The following is the roster of the Committee at the time of approval of this Standard.)STANDARDS COMMITTEE OFFICERSJ. Meyer, ChairJ. Frey, Vice ChairA. Maslowski, SecretarySTANDARDS COMMITTEE PERSONNELR. Appleby, ExxonMobil Pipeline Co .C. Becht IV, Becht Engineering Co.K.
33、Bodenhamer, TRC Pipeline ServicesR. BojarczukM. R. Braz, MRBraz however, they should not contain proprietary names orinformation.viiiRequests that are not in the format described above may be rewritten in the appropriate format by the Committee priorto being answered, which may inadvertently change
34、the intent of the original request.Moreover, ASME does not act as a consultant for specific engineering problems or for the general application orunderstanding of the Standard requirements. If, based on the inquiry information submitted, it is the opinion ofthe Committee that the Inquirer should see
35、k assistance, the inquiry will be returned with the recommendationthat such assistance be obtained.ASME procedures provide for reconsideration of any interpretation when or if additional information that might affectan interpretation is available. Further, persons aggrieved by an interpretation may
36、appeal to the cognizant ASMECommittee or Subcommittee. ASME does not “approve, ” “certify, ” “rate, ” or “endorse” any item, construction, proprietarydevice, or activity.Attending Committee Meetings. The B31 Standards Committee regularly holds meetings and/or telephone confer-ences that are open to
37、the public. Persons wishing to attend any meeting and/or telephone conference should contact theSecretary of the B31 Standards Committee.ixINTENTIONALLY LEFT BLANKxSTANDARD HEAT TREATMENTS FOR FABRICATION PROCESSES1 INTRODUCTIONThis Standard provides requirements for heat treat-ment of piping assemb
38、lies that meet the requirementsof ASME B31 Code Sections. These requirements apply to(a) preheating(b) postweld heat treatment (PWHT)(c) postforming heat treatment (PFHT) required by theASME B31 Code Sections for other fabrication processes,including forming processes such as bending(d) heat treatme
39、nts required by contract specificationsThe heat treatments addressed in this Standard includeweld preheating, PWHT, PFHT, and heat treatment inorder to enhance material properties resulting from fabri-cation. Weld preheating is generally required on harden-able steels in order to reduce local hardne
40、ss or to reducethe occurrence of hydrogen cracking. Preheat is typicallyrequired based on both hardenability (as indicated by theP-Number) and thickness at the weld. A minimumtemperature for all materials prior to initiating a weldis expected to be needed to reduce the possibility ofcondensation. It
41、 should be noted that weld preheat isnot usually considered a heat treatment, but it is a require-ment of the ASME B31 Code Sections.PWHT is generally required on hardenable steels inorder to temper any hardened areas or to reduce residualstress in the weldment. PFHT may be used to addressreduction
42、of the properties within the bend after hotbending or to address the effects of strain after coldbending (the additional strain may cause a degradationof creep rupture properties when the operation is athigh temperatures). In some cases of PWHT, PFHT, ormaterial heat treatments, non-standard heat tr
43、eatmentmay be required by the contract specification, e.g., anaustenitizing heat treatment or a solution heat treatment.This Standard is intended to provide consistent codeheat treatment rules. It may be incorporated by referencein a code, or it can become a basis for code or contractrequirements.Ap
44、pendices provide more-specific controls that may beneeded or desired for specific applications. These specificcontrols are not mandatory unless specified.Appendices are also included that outline alternativemethods to exempt PWHT of welds when PWHT is difficultor impossible. The alternatives are req
45、uired to beaddressed within Welding Procedure Specifications(WPS) qualified in accordance with ASME Boiler andPressure Vessel Code (BPVC), Section IX.The requirements for the heat treatments done in accor-dance with material or product specifications are notaddressed within this Standard. Such heat
46、treatmentsare governed by those specifications.2 GLOSSAR Ycreep strength enhanced ferritic (CSEF) steel: steel in whichthe microstructure, consisting of lower transformationproducts, e.g., martensite or bainite, is stabilized bycontrolled precipitation of temper-resistant carbides,carbonitrides, and
47、/or nitrides.heat treatments:annealing, full: heating a metal to a temperature abovethe transformation temperature range and holding itabove that range for a proper period of time, followedby cooling to below that range.austenitizing: heat treatment where a partial orcomplete phase transformation to
48、 austenite occurs.normalizing: a process in which a ferrous metal isheated to a suitable temperature above the transforma-tion range and is subsequently cooled in still air at roomtemperature.quenching: a process in which a ferrous metal is heatedto a suitable temperature above the transformation ra
49、ngeand is subsequently rapidly cooled in a selected quenchingmedium.tempering: reheating a hardened metal to a temperaturerange below the transformation range.interpass temperature: the highest temperature in theweld joint immediately prior to welding, or in the caseof multiple pass welds, the highest temperature in thearea of the previously deposited weld metal, immediatelybefore the next pass is started.postforming heat treatment (PFHT): any heat treatmentsubsequent to a bending or forming operation.postweld heat treatment (PWHT): any heat treatmentsubsequent to welding.postweld hydrogen
