ASTM_A_844_-_A_844M_-_09_2015.pdf

Designation:A844/A844M09(Reapproved 2015)Standard Specification forSteel Plates,9%Nickel Alloy,for Pressure Vessels,Produced by the Direct-Quenching Process1This standard is issued under the fixed designation A844/A844M;the number immediately following the designation indicates the yearof original adoption or,in the case 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.Scope1.1 This specification covers 9%nickel-alloy steel platesproduced by the direct-quenching process.The plates areintended primarily for use in welded pressure vessels.1.2 The direct-quenching process consists of quenching theplates directly after rolling,without permitting the plates tocool below the critical temperature prior to initiation of thequenching operation,and subsequently tempering the plates.(This differs from the“conventional”process in which theplates are permitted to cool to a temperature significantlybelow the critical temperature,usually to ambient temperature,prior to reheating to a temperature above the upper criticaltemperature,then quenching,and subsequently tempering.)1.3 The maximum nominal thickness of plates furnishedunder this specification shall not exceed 2 in.50 mm.1.4 This material is susceptible to magnetization.Use ofmagnets in handling after heat treatment should be avoided ifresidual magnetism would be detrimental to subsequent fabri-cation or service.1.5 The values stated in either inch-pound or SI units are tobe regarded separately as standard.Within the text,the SI unitsare shown in brackets.The values stated in each system are notexact equivalents;therefore each system must be used inde-pendently of the other.Combining values from the two systemsmay result in nonconformance with the specification.2.Referenced Documents2.1 ASTM Standards:2A20/A20M Specification for General Requirements for SteelPlates for Pressure VesselsA435/A435M Specification for Straight-Beam UltrasonicExamination of Steel PlatesA577/A577M Specification for Ultrasonic Angle-Beam Ex-amination of Steel PlatesA578/A578M Specification for Straight-Beam UltrasonicExamination of Rolled Steel Plates for Special Applica-tions3.General Requirements and Ordering Information3.1 Material supplied to this material specification shallconform to Specification A20/A20M.These requirements out-line the testing and retesting methods and procedures,permit-ted variations in dimensions,quality and repair of defects,marking,loading,and ordering information.3.2 Inadditiontothebasicrequirementsofthisspecification,certain supplementary requirements are availablewhen additional control,testing,or examination is required tomeet end use requirements.The purchaser is referred to thelisted supplementary requirements in this specification and tothe detailed requirements in Specification A20/A20M.3.3 If the requirements of this specification are in conflictwith the requirements of Specification A20/A20M,the require-ments of this specification shall prevail.4.Manufacture4.1 Steelmaking PracticeThe steel shall be killed andshall conform to the fine austenitic grain size requirement ofSpecification A20/A20M.4.2 Heat Treatment:4.2.1 The plates shall be quenched directly after rolling,without being allowed to cool below 1205F 650C.Thequenching shall be initiated from a temperature within therange from 1205 to 1670F 650 to 910C.(The temperatureshall be reported in accordance with 19.2 of SpecificationA20/A20M.)4.2.2 Subsequent to quenching,the plates shall be temperedwithin the range from 1050 to 1175F 565 to 635C,holdingat that temperature for a minimum of 30 min/in.1.2 min/mmof thickness but for not less than 15 min.,and then cooling ata rate of not less than 300F/h 165C/h,either in air or byquenching in water,to ambient temperature.4.2.2.1 Prior to the tempering treatment,the plates may besubjected to an intermediate heat treatment consisting of1This specification is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.11 on Steel Plates for Boilers and Pressure Vessels.Current edition approved Sept.1,2015.Published September 2015.Originallyapproved in 1985.Last previous edition approved in 2009 as A844/A844M 09.DOI:10.1520/A0844_A0844M-09R15.2For 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 standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 heating to a temperature in the range from 1165 to 1290F 630to 700C,holding at that temperature for a minimum of 1 h/in.(2.4 min/mm of thickness,but in no case less than 15 min,andthen water-quenching to below 300F 150C in the case ofplate thicknesses of more than