... furface quality, high precision dimension. Boiler Seamless steel Pipe Standards and Grades:GB5310, GB3087, 10#, 20#, 20G, 20MnG,12Cr1MoVG, ... 23/ 24/ 25/ 26)JIS G3462 Alloy Steel for Boiler and Heat Exchanger Tubes (STBA12/ 13/ 20/ 22/23)JIS G3467 Steel ... 480mm, W.T. 2- 60mm.Application: Generally for boilers and heat exchangersDimensions, Mechanical properties, Chemical compositions: Refer to ASTM A355, ...