... Standard: ASME SA213M; Specification: Outer Diameter 16~168.3, Thickness 1~15 Seamless Ferritic and Austenitic Alloy Steel Boiler Super heater and Heat ... Exchanger TubesSteel Grade: T91,T23, T22,T12,T11,T5,T2 etc;Standard: ASME SA213M;Specification: ... to high temperature service such as for super-heaters and reheaters. And the features are precise dimension.