Abstract: Finned tubing for use in heat exchangers has tapered helical fins with serrations disposed between connecting webs. The opposed edges of the serrations, interior of the periphery, taper to a relatively sharp edge. Shark-fin like protuberances project outwardly adjacent one leg of each serration with each protuberance having a flange thereon. In one modification, the serrations on adjacent fins are spirally aligned. One method and apparatus of producing the finned tubing subjects a tensioned strip to graduated compression to curl the strip onto a tube to form fins, while simultaneously relieving a portion of the compression at spaced points along the periphery of the strip, resulting in a tearing of the strip to provide the serrations, and the adjacent protuberances. The protuberances are then compressed by rollers to form the flanges. An apparatus for carrying out the method includes a pair of rotary members to taper and curl the strip, with one of the rotary members having a series of recesses.