1、Designation: A420/A420M 10aStandard Specification forPiping Fittings of Wrought Carbon Steel and Alloy Steel forLow-Temperature Service1This standard is issued under the fixed designation A420/A420M; the number immediately following the designation indicates the yearof original adoption or, in the c
2、ase of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This specification2covers wrought carbon steel andalloy steel fittings of seamless and w
3、elded construction, cov-ered by the latest revision of ASME B 16.9, ASME B 16.11,MSS SP-79, MSS SP-83, MSS SP-95, and MSS SP-97.Fittings differing from these ASME and MSS standards shallbe furnished in accordance with Supplementary RequirementS58 of SpecificationA960/A960M. These fittings are for us
4、e inpressure piping and pressure vessel service at low tempera-tures.1.2 Optional supplementary requirements are provided forfittings where a greater degree of examination is desired. Whendesired, one or more of these supplementary requirements shallbe specified in the order.1.3 This specification i
5、s expressed in both inch-pound unitsand in SI units. However, unless the order specifies theapplicable “M” specification designation (SI units), the mate-rial shall be furnished to inch-pound units.1.4 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard.
6、 Within the text, theSI units are shown in brackets. The values stated in eachsystem may not be exact equivalents; therefore, each systemshall be used independently of the other. Combining valuesfrom the two systems may result in non-conformance with thestandard.2. Referenced Documents2.1 In additio
7、n to those Referenced Documents listed inSpecification A960/A960M, the following list of standardsapply to this specification.2.2 ASTM Standards:3A960/A960M Specification for Common Requirements forWrought Steel Piping Fittings2.3 ASME Standards:B 16.9 Factory-Made Wrought Steel Butt-Welding Fitting
8、s4B 16.11 Forged Steel Fittings, Socket-Welding Threaded4Section VIII Division 1, Pressure Vessels4Section IX Welding Qualifications2.4 MSS Standards:MSS SP-25 Standard Marking System for Valves, Fittings,Flanges, and Unions5MSS SP-79 Socket Welding Reducer Inserts5MSS SP-83 Steel Pipe Unions, Socke
9、t-Welding andThreaded5MSS SP-95 Swage(d) Nipples and Bull Plugs5MSS SP-97 Integrally Reinforced Forged Branch OutletFittingsSocket Welding, Threaded and ButtweldingEnds2.5 ASNT Standards:SNT-TC-1A Recommended Practice for NondestructiveTesting Personnel Qualification and Certification63. Ordering In
10、formation3.1 See Specification A960/A960M.4. General Requirements4.1 Product furnished to this specification shall conform tothe requirements of Specification A960/A960M, including anysupplementary requirements that are indicated in the purchaseorder. Failure to comply with the general requirements
11、ofSpecification A960/A960M constitutes non-conformance withthis specification. In case of conflict between the requirements1This specification is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.22 on Steel F
12、orgings and Wrought Fittings for Piping Applications and BoltingMaterials for Piping and Special Purpose Applications.Current edition approved Nov. 1, 2010. Published December 2010. Originallyapproved in 1958. Last previous edition approved in 2010 as A420/A420M10.DOI: 10.1520/A0420_A0420M-10a.2For
13、ASME Boiler and Pressure Vessel Code applications see related Specifi-cation SA-420 in Section II of that Code.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the s
14、tandards Document Summary page onthe ASTM website.4Available from American Society of Mechanical Engineers (ASME), ASMEInternational Headquarters, Three Park Ave., New York, NY 10016-5990, http:/www.asme.org.5Available from Manufacturers Standardization Society of the Valve and FittingsIndustry (MSS
15、), 127 Park St., NE, Vienna, VA 22180-4602, http:/www.mss-.6Available fromAmerican Society for Nondestructive Testing (ASNT), P.O. Box28518, 1711 Arlingate Ln., Columbus, OH 43228-0518, http:/www.asnt.org.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International
16、, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.of this specification and Specification A960/A960M, thisspecification shall prevail.5. Material5.1 The material for fittings shall consist of forgings, bars,plates, seamless or fusion welded tubular products with f
17、illermetal added. It shall conform to the chemical requirements inTable 1, and be made by one of the following processes:open-hearth, basic-oxygen, or electric-furnace. The steels shallbe made using recognized melting practices necessary toproduce steels that shall meet the impact requirements of th
18、isspecification.6. Manufacture6.1 Forging or forming operations shall be performed byhammering, pressing, piercing, extruding, upsetting, working,bending, fusion-welding, or machining, or by a combination oftwo or more of these operations. The forming procedure shallbe so applied that it will not pr
19、oduce injurious defects in thefittings.6.2 All welds, including welds in tubular products fromwhich fittings are made, shall be (1) made by welders, weldingoperators and welding procedures qualified under the provi-sions of ASME Section IX,(2) heat treated in accordance withSection 7 of this specifi
20、cation, and (3) nondestructively exam-ined throughout the entire length of each weld in accordancewith Section 14 of this specification. The radiography of weldsshall be done either prior to or after forming at option ofmanufacturer. Personnel performing NDE examinations shallbe qualified in accorda
21、nce with SNT-TC-1A.6.3 The welded joints of the fittings shall be finished inaccordance with the requirements of Paragraph UW-35 (a) ofSection VIII, Division 1 of ASME Boiler and Pressure VesselCode.6.4 All butt-weld tees manufactured by cold-forming meth-ods shall be liquid penetrant or magnetic pa
22、rticle examined byone of the methods specified in Supplementary RequirementS52 or S53 of Specification A960/A960M. This examinationshall be performed after final heat treatment by NDE personnelqualified under the provisions of SNT-TC-1A. Only the side-wall areas of the tee need be examined. This are
23、a is defined bya circle that covers the area from the weld bevel of the branchoutlet to the centerline of the body or run. Internal and externalsurfaces shall be examined when size permits accessibility.After the removal of any cracks, the tees shall be re-examinedby the original method. Acceptable
24、tees shall be marked withthe symbol PT or MT, as applicable, to indicate compliance.6.5 Stubends may be produced with the entire lap added bythe welding of a ring, made from plate or bar of the same alloygrade and composition, to the outside of a straight section ofpipe, provided the weld is double
25、welded, is a full penetrationjoint, satisfies the requirements of 6.2 for qualifications andradiography and 7.1 for post weld heat treatment.7. Heat Treatment7.1 All fittings shall be furnished in the normalized, normal-ized and tempered, annealed, or quenched and temperedcondition. All welding shal
26、l be completed prior to the austen-itizing heat treatment.7.2 The full thickness of the material from which impact testspecimens are to be obtained shall be heat treated with afurnace charge as specified in 10.4.2 or 10.4.3.7.3 After forming, the fittings shall be allowed to cool belowthe lower crit
27、ical before applying one of the heat treatmentslisted in 7.1.7.4 When specified in the order, the test specimens shall besubjected to a simulated post-weld heat treatment beforetesting. The simulated post-weld heat treatment used shall beas shown in Table 2, unless the purchaser has otherwisespecifi
28、ed in the order.8. Chemical Composition8.1 The steel shall conform to requirements of chemicalcomposition for the respective material prescribed in Table 1.8.2 The steel shall not contain any unspecified elements forthe ordered grade to the extent that it then conforms to therequirements of another
29、grade for which that element is aspecified element having a required minimum content.8.3 The chemical composition of weld metal is not requiredto meet the same limits of the base materials however, thecomposition of the weld deposit shall be such that it meets theminimum mechanical and impact requir
30、ements of this specifi-cation. In general, the alloy content shall be similar to that ofthe base metal but shall not exceed 6 % except in the case offittings of 9 % nickel steel.8.4 A product analysis is optional.9. Tensile Properties9.1 The tensile properties of the fittings material shallconform t
31、o the requirements for the applicable grade ofmaterial as listed in Table 3.TABLE 1 Chemical RequirementsNOTE 1All requirements are maximum unless otherwise indicated.NOTE 2Where an ellipsis (.) appears in this table, there is no requirement.GradeAComposition, %CMnP S Si Ni Cr Mo Cu Cb VWPL6 0.30 0.
32、501.35 0.035 0.040 0.150.40 0.40 0.30 0.12 0.40 0.02B0.08WPL9 0.20 0.401.06 0.030 0.030 . . . 1.602.24 0.751.25WPL3C0.20 0.310.64 0.05 0.05 0.130.37 3.23.8 . . .WPL8D0.13 0.90 0.030 0.030 0.130.37 8.49.6 . . .AWhen fittings are of welded construction, the symbols above shall be supplemented by the l
33、etter “W”.BBy agreement, the limit for Columbium may be increased up to 0.05 % on heat analysis and 0.06 % on product analysis.CFittings made from plate or forgings may have 0.90 % max manganese.DFittings made from plate may have 0.98 % max manganese.A420/A420M 10a29.2 At least one tension test shal
34、l be made on each heat ofmaterial and in the same condition of heat treatment as thefinished fittings it represents provided that the wall thickness ofthe fitting and the representative sample thickness do not varymore than14 in. 6 mm. At least one tension test per heat ofweld metal shall be made af
35、ter heat treatment in the samemanner as the base metal. Results need not be reported unlessSupplementary Requirement S51 of Specification A960/A960M is specified.9.3 Records of the tension tests shall be certification that thematerial of the fitting meets the tensile requirements of thisspecificatio
36、n.10. Impact Test Properties10.1 Properties:10.1.1 The notched bar impact properties of the base metaland weld metal shall conform to the requirements of Table 4 orTable 5 for the applicable grade of material.10.1.2 RetestWhen the average value of the three speci-mens equals or exceeds the minimum v
37、alue permitted for asingle specimen and the value for more than one specimen isbelow the required average value, or when the value for onespecimen is below the minimum value permitted for a singlespecimen, a retest of three additional specimens shall be made.The value for each of these retest specim
38、ens shall equal orexceed the required average value. When an erratic result iscaused by a defective specimen, or there is uncertainty in testprocedure, a retest shall be allowed.10.2 Procedures:10.2.1 All material furnished under this specification shallbe tested for impact resistance at the tempera
39、ture for therespective grade in Table 6. Exceptions to these requirementsare permissible when agreed upon between the purchaser andproducer and specified in the order, in that the impact test isacceptable when made at temperatures different from thoseshown in Table 6, provided the test temperature i
40、s at least aslow as the intended service temperature, and fittings aresuitably marked in accordance with Section 18 to identify thereported test temperature.10.2.2 The notched-bar impact test shall be made in accor-dance with the procedure for the simple-beam, Charpy-typetest specified in Specificat
41、ion A960/A960M. Each impact testshall consist of breaking three specimens.10.3 Specimens:10.3.1 Notched-bar impact specimens shall be simple-beam,Charpy-type A with a V-notch. Standard specimens 10 by 10mm in cross section shall be used unless the material to betested is of insufficient thickness, i
42、n which case the largestobtainable standard subsize impact specimens shall be used.When the size or shape of the finished fittings is insufficient topermit obtaining the smallest standard subsize impact speci-mens, an impact test by the fitting manufacturer will not berequired. The material from whi
43、ch the specimens are takenshall be heat treated with a furnace charge in accordance with10.4.2 or 10.4.3. Impact tests shall be made from either the rawmaterial from which the fittings are made or from a finishedfitting at the option of the manufacturer.10.3.2 Test specimens shall be obtained so tha
44、t the longitu-dinal axis of the specimen is parallel to the longitudinal axis ofthe fitting while the axis of the “V” shall be perpendicular tothe surface. On wall thickness over 1 in. 25 mm thespecimens shall be obtained with their longitudinal axis located12 in. 13 mm from the outer surface.10.3.3
45、 When testing welds, the notch of the specimen shallbe in the welded joint and, where the diameter and wallthickness permit, the longitudinal axis of the specimen shall betransverse to the longitudinal axis of the weld. The axis of thenotch shall be perpendicular to the surface.10.4 Number of Tests:
46、10.4.1 A notched-bar impact test, consisting of breakingthree specimens shall be made. Each test shall represent onlysuch fittings from a heat that do not vary from the thickness ofthe material from which the test specimens are taken by morethan14 in. 6 mm.10.4.2 When heat treatment is performed in
47、furnaces notequipped with calibrated recording pyrometers, one impact testshall be made for each heat in each heat-treatment load. Testspecimens shall be included with each furnace charge. If thisheat treatment is conducted in continuous-type furnaces notequipped with calibrated recording pyrometers
48、, then one testper heat shall be conducted for each 5000 lb or 2550 kg (orless) of product.10.4.3 When heat treatment is performed in furnaces con-trolled within a 50 F 28 C range and equipped withcalibrated recording pyrometers so that records of heat treat-ment are available, then one impact test
49、from each heat isrequired, provided that all other heat treatments are conductedat the same temperatures and within the same 50 F 28 Crange as the furnace charge that contained the test specimens.10.4.4 On fittings of welded construction, additional impacttests of the same number as required in 10.4.1 or 10.4.2 shallbe made to test the weld metal.10.4.5 Specimens showing defects while being machined orprior to testing shall be discarded, and replacements shall beconsidered as original specimens.10.5 Retreatment:10.5.1 If the results of impact
