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.

1.1 This specification covers 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.

1.2 The tubing sizes and thicknesses usually furnished to this specification are 1/2 to 5 in. [12.7 to 127 mm] in outside diameter and 0.035 to 0.320 in. [0.9 to 8.1 mm], inclusive, in minimum wall thickness. Tubing having other dimensions may be furnished, provided such tubes comply with all other requirements of this specification.

1.3 Mechanical property requirements do not apply to tubing smaller than 1/8 in. [3.2 mm] in inside diameter or 0.015 in. [0.4 mm] in thickness.

1.4 An optional supplementary requirement is provided for non-destructive examination for certain ASME applications.

1.5 The values stated in either inch-pound units or SI units are to be regarded separately as the standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification. The inch-pound units shall apply unless the "M" designation of this specification is specified in the order.