... JIS G3458, G3467, etc. Material Carbon Steel, Alloy steel. steel tube Standards and Grades:GB5310, GB3087, 10#, 20#, ... 24/ 25/ 26) JIS G3462 Alloy Steel for Boiler and Heat Exchanger Tubes (STBA12/ 13/ 20 ... / 22/23) JIS G3467 Steel Tubes ... 2- 60mm. Application: Generally for boilers and heat exchangersDimensions, Mechanical properties, Chemical compositions: ...