... 2.E255,E355,E235 3.BK,NBK,BKS,GBK 4.Ra<1.0u, tolerance on OD+/-0.5 seamless steel pipe Phosphate ... Seamless Steel Pipe1) Certificate: ISO9001:2000, TS16949:2009,2) Spec ... .: DIN2391/C,3) Steel Gr.: St35, St37, ST37.4, St45, St52, St52-34) O ...