carbon steel seamless tube 1.Size:1/2" to72" 2.Thickness:2.0 to 60mm 3.Standards:ASTM A106/53 B, ... API 5L GR. B. carbon steel seamless tube 1 ... B, ST37, ST44, ST52, S355JR3) Size: From 1/2" to 72"4) Wall Thickness: SCH20 to SCH80, ... : ISO, API, ASTM, DIN etc. 2) Mill Test Certificate: EN10204/3.1B3) Third party inspection: SGS, BV, ...