... :2-30mm Seamless Alloy pipe per ASTM A213M ASTM A335 for boiler, superheater, and heat-exchanger tubersOD: 21.3mm-711mmWH:sch10-schXxs ... ,P9,P11,P22, P91, P92 Standard Specification for seamless Ferritic and Austenitic Alloy-steel boiler, superheater,and heat-exchanger tube Alloy Steel ...