... Tubes for low and Medium Pressure Boilers Size: 1/4"-24" Certificate: ISO, API Seamless Steel Tubes for low and Medium Pressure ... Steel TubesGB3087-199910, 20ASTM A179, ASTM A192for low and Medium Pressure BoilersASTM SA179,SA192, BS3059Seamless Steel TubesGB6479 ... , 10MoVNb, 12CrMo, 15CrMo, 12Cr2MoISO 9329-2-1997 for high pressure --Chemical fertilizer equipmentASTM A161-94Seamless steel tubesGB9948 ...