... , L555M, L625M, L690M, H40, J55, K55, M65, L80, C95, N80,Q125, S235GT, S195T, Grade 1, Grade 2, Grade 3, ST33 ... STK290, STK400, STK490, STK500,STK540,STPG370, STPG410 etc.CertificateEN10217, EN10219, API 5L PSL1/ PSL2, KS 4602, KS3583, GB/T9711.1/2 ... systems in the petroleum and natural gas industries-for use as casing and tubing for wells, screwed and socketed steel tubes and tubularand for plain end ...