ASME_B31.12-2019.pdf

Hydrogen Piping and PipelinesASME Code for Pressure Piping,B31AN AM E R IC A N NAT IO NAL STANDARDASME B31.12-2019(Revision of ASME B31.12-2014)ErratatoASME B31.12-2019Hydrogen Piping and PipelinesParagraph GR-3.9.2 was inadvertently omitted from ASME B31.12-2019,page 48.The corrected page follows this cover sheet.THE AMERICAN SOCIETY OF MECHANICAL ENGINEERSTwo Park Avenue,New York,NY 10016-5990February 2020GR-3.9 FORMING OF PIPE COMPONENTSPipe may be bent and components may be formed byanyhotorcoldmethodthatissuitableforthematerial,theintended service,and the severity of the bending orforming process.When selecting material for hydrogenservice,consideration shall be given to the effects ofcold working,which may promote lower resistance toHE,while hot working enhances resistance to HE.Thefinished surface shall be free of cracks and substantiallyfree from buckling.Thickness after bending or formingshall be not less than that required by the engineeringdesign.GR-3.9.1 Bending Requirements(a)Flattening.Flattening of a bend,the differencebetween maximum and minimum diameters at anycross section,shall not exceed 8%of nominal outsidediameter for internal pressure and 3%for external pres-sure.Removal of metal shall not be used to achieve theserequirements.(b)Bending Temperature(1)Coldbendingofferriticmaterialsshallbedoneata temperature below the transformation range.(2)Hotbendingshallbedoneatatemperatureabovethe transformation range and in any case within atemperature range consistent with the material andthe intended service.(c)Corrugated and Other Bends.Dimensions andconfigurationshall conformtoadesignqualified inaccor-dance with para.IP-3.8.2 or para.PL-3.7,as applicable.(d)Hot Bending and Forming.After hot bending andforming,heat treatment is required for P-Nos.1,3,4,5A,and 5B materials in all thicknesses.Durations andtemperatures shall be in accordance withTable GR-3.6.1-1.(e)Cold Bending and Forming.After cold bending andforming,heat treatment is required(for all thicknesses,and with temperature and duration as given inTable GR-3.6.1-1)when any of the following conditionsexist:(1)for P-Nos.1 through 5A and 5B materials,wherethemaximumcalculatedfiberelongationafterbendingorforming exceeds50%of specified basic minimum elonga-tion(in the direction of severest forming)for the appli-cable specification,grade,and thickness.Thisrequirement may be waived if it can be demonstratedthat the selection of pipe and the choice of bending orforming process provide assurance that,in the finishedcondition,the most severely strained material retainsat least 10%elongation.(2)for any material requiring impact testing,wherethemaximumcalculatedfiberelongationafterbendingorforming will exceed 5%.(3)when specified in the engineering design.GR-3.9.2 Post-Heat TreatmentGR-3.1019HARDNESS TESTINGHardness testing shall be conducted for welding proce-dure qualification tests for those materials with accep-tance criteria described in Table GR-3.10-1.Base metalfor welding procedure qualification tests shall be madefrom the same base metal specification(same P-Number and Group Number),similar in chemistry,andin the same heat treatment condition as specified forthe piping.The thickness of base metal coupons shallnot be less than the piping.(a)Method(1)The hardness survey shall be performed on atransverse weld cross section that has been polishedandetchedtoidentifytheweldmetal,fusionline,andHAZ.(2)The hardness test shall be carried out in accor-dance with ASTM E92 using a 10-kg load.Other hardnesstesting methods for welding procedure qualification maybe used when permitted by the engineering design.(3)TwoVickershardnesstraversesoftheweldjointshould be made on a weld sample in the minimum PWHTcondition.Thesehardnesstraversesshouldbeperformedat1.5mm(116in.)fromtheinternalandexternalsurfacesas shown in Figure GR-3.10-1.The HAZ readings shouldinclude locations as close as possible approximately 0.2mm(0.008 in.)to the weld fusion line.Each traverseincludes 10 hardness readings for a total of 20 hardnessreadings per weld sample.(b)Acceptance Criteria(1)Hardness measurements shall not exceed thelimits of Table GR-3.10-1 after the required PWHT.Other hardness testing limits may be used if specifiedin the engineering design.(2)The hardness data shall be reported on the PQR.Table GR-3.10-119Hardness Testing Acceptance CriteriaBase Metal P-No.Note(1)Base MetalGroupVickers HV 10 Max.Hardness Note(2)1Carbon steel2353Alloy steels,Cr 12%2354Alloy steels,12%Cr 2%2355A,5BAlloy steels,214%Cr10%248NOTE:(1)P-Number from ASME BPVC,Section IX,QW/QB-422.(2)When other hardness testing methods are used,the acceptancecriteria shall be equivalent to these Vickers HV 10 values.ASME B31.12-201948Post-heat treatment,when required for pipe compo-nents after bending or forming,shall be performed inaccordance with para.GR-3.6,including Table GR-3.6.1-1.ASME B31.12-2019(Revision of ASME B31.12-2014)Hydrogen Pipingand PipelinesASME Code for Pressure Piping,B31AN AMERICAN NATION