This specification covers external helical, integral finned, seamless or welded low-carbon steel tubes for use in tubular heat exchangers, surface condensers, evaporators, superheaters, and similar heat-transfer apparatus in unfinned end diameters. The tube, prior to finning operation or unfinned portions of the finned tube, shall conform to the requirements for tensile properties prescribed in the governing plain-tube specification. Each tube after finning shall be subjected to a pressure test which shall permit easy visual leakage detection.