ASTM A178/A178M, ASME SA178/SA178M is the standard applicable to electric-resistance-welded carbon steel and carbon manganese steel boiler and superheater tubes.

ASTM A178 Standard covers minimum-wall-thickness, electric-resistance-welded tubes made of carbon steel and carbon-manganese steel intended for use as boiler tubes, boiler flues, superheater flues, and safe ends.

SA178 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 0.360 in. [0.9 to 9.1 mm], inclusive, in minimum wall thickness. Tubing having other dimensions may be furnished, provided such tubes comply with all other requirements of this specification.