ASTM A179 heat exchanger tubes A 179 Standard Specification for Seamless Cold-Drawn Low-Carbon Steel Heat-Exchanger and Condenser Tubes This specification covers minimum-wall-thickness, seamless cold-drawn low-carbon steel tubes for tubular heat exchangers, condensers, and similar heat transfer apparatus. This specification covers tubes 1/8 to 3 in. [3.2 to 76.2 mm], inclusive, in outside diameter.