SA 213 T22 is a ferritic alloy steel boiler tube. It is used in superheater elements and heat exchangers, condensers, marine applications, paper pulping, and petrochemicals. SA 213 T91 is a boiler tube made of boiler grade alloy. It is used in the petrochemical industry. These tubes come in various shapes and sizes. Materials are used like carbon, manganese, phosphorus, sulfur, silicon, molybdenum, vanadium, nitrogen, nickel, etc.