A guideline of fitness−for−service assessment to hydrogen damage is introduced to API 5 7 9−1/ASME FFS−1 Code.Fitness−For−Service(FFS)assessment procedures are provided in this Part for low strength ferritic steel pressurized components with hydrogen induced cracking(HIC)and blisters,stress oriented HIC(SOHIC)damage, and components with laminations that Part 1 3 directs that Part 7 shall be used(e. g.the component operates in a hydrogen charging environment or closely spaced laminations at

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... rent depths in through−thickness direction) . These forms of damage are further described below and in NACE Standard SP0 2 9 6−1 0 Detection,Repair,and Mitigation of Cracking in Refinery Equipment in Wet H2S Environments. This Part excludes sulfide stress cracking(SSC)and hydrogen embrittlement of high strength steels which generally occur in steels with a hardness above Rockwell C 2 2(Brinell 2 3 7)or with tensile strengths above 7 9 3 MPa(1 1 5 ksi) .The technical basis for Part 7 is summarized in Annex 7A FFS