... 4:Wall thickness:2-30mm Seamless Alloy pipe per ASTM A213M ASTM A335 for boiler, superheater, and heat-exchanger tubersOD: 21.3mm ... schXxs ASTM A213M :T1, T5, T9,T11,T22, T91, T91ASTM A335: P1,P5,P9,P11,P22, P91, P92 Standard Specification for ... seamless Ferritic and Austenitic Alloy-steel boiler, superheater,and heat-exchanger tube Alloy Steel Pipe ASTM A213