Standard for malerials and wielding from Chinese classifying society Chinese clasifying society(CCS)
Standard of DNV Det Norske Veritas(DNV)
Standard of Lloyd’S Register of UK(LR)　Lloyd’S Register of UK(LR)
Standard of Germanischer Lloyd Germanischer Lloyd(GL)
Standard of American Bureau of Shipping(ABS)American Bureau of Shipping(ABS)
Standard of BUREAU VERITAS(BV)BUREAU VERITAS(BV)
Standard of RINA Italian classification society(RINA)
Standard of NIPPON KAIJI KYOKAI(NK)NIPPON KAIJI KYOKAI(NK)

GB/T5312 Chinese national standard

Appication:
Seamless steel tubes for manufacturing marine boilers and ovemeaters as we as pressure pipes opf grade I and II

Model N0. of major steel tubes
320, 360, 410, 460, 490, etc.

Note:
residual elements:Cr<=0.25%,  Mo<=0.10%,  Ni<=0.30%, Cu<=0.30%, aggregate<=0.70%