ASTM A 250

This guide covers standard specification for several grades, designated T1, T1a, T1b, T2, T11, T12, and T22, of minimum-wall-thickness, electric-resistance-welded, carbon-molybdenum and chromium-molybdenum alloy-steel, boiler and superheater tubes. Product analysis shall be done wherein the material shall conform to the required chemical composition for carbon, manganese, phosphorus, sulfur, silicon, molybdenum, and chromium. The material shall conform to the required tensile properties, namely: tensile strength, yield strength, and elongation. The computed minimum elongation values for steel with decreasing wall thickness shall be given. The tubes shall have a hardness not exceeding the specified values for Brinell hardness and Rockwell hardness numbers. When the final heat treatment is in a continuous furnace, the number of tubes of the same size and from the same heat in a lot shall be determined from the given size of the tubes. Required mechanical tests such as tensile test, flattening test, flange test, reverse flattening test, hardness test, and hydrostatic or nondestructive electric tests, shall be performed on the steel specimen.