pressure boiler tube: standards and grades:GB5310,GB3087,10#,20#,20G,20MnG, ... ASTM A335(P1/P11/P12/P2/P22/P5/P9 pressure boiler tube:Application:Generally for boilers and heat exchangersDimensions,mechanical properties ... :bundlesomerwith or without edge protector,as per custtomers' requirement pressure boiler tube