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