Abstract: A tube for heat transfer systems or the like is provided which includes helically or circumferentially disposed, radially extending ribs or fins. The base of the grooves defined between adjacent fins has a plurality of discrete impressions defined therein. The provision of discrete impressions in the groove base improves the heat transfer characteristics of the tube by greatly increasing the outer surface area of the tube relative to the inner surface area of the tube.

Abstract: This invention concerns finned tubes for use in heat exchanging whereby the fins have a generally T or Y shape. There is disclosed process and apparatus for making these Y and T-finned tubes whereby a smooth tube is subjected to conventional rolling process with the ends of the fins being subsequently notched into Y-fins and, if desired, subsequently flattened into T-fins. According to other embodiments of the invention the T-fins are constructed by an apparatus including an oblique surface which contacts the conventionally constructed fins causing the fins to be flattened into a general T shape.

Abstract: This invention concerns finned tubes for use in heat exchanging whereby the fins have a generally T or Y shape. There is disclosed process and apparatus for making these Y and T-finned tubes whereby a smooth tube is subjected to a rolling process with notching rollers being arranged between rolling discs. Bending rollers can be used to form Y fins and, if desired these can be subsequently flattened into T-fins.