steel pipe ,tube 1.Standard:BS,ASTM,GB/T,DIN 2.Material: ... authentication CompanyTianJin RuiTong Steel Co., Ltd.TypeSteel Pipe (or tube) ManufacturerPlace of originChinaGradeQ195,Q215,Q235,Q345,X42,X60,X65,X70 ... 5LST33DIN2391 GB/T3091A252API5CTST35 GB/T3094A53Gr.AAPI LINE PIPEST38 GB9948-88A53Gr.B ST45 GB8162-1999A795 ST52 CertificatesISO , API , Quality System Certificates ,Manufacturing MethodCold ...