The major uses for high frequency welded finned tubes are in the heat recovery associated with boilers for power generation and in furnace applications for the petrochemical industry.
The steel fin, that may be solid or serrated, is helically wound and continuously welded to the tube by high frequency electric resistance welding. This produces a homogeneous, clean and continuous fin-to-tube bond with no additional weld material, for a very efficient heat flow and resistance to corrosion.
The use of high-frequency current results in much localized heating of the tube surface and the edge of the fin. This skin effect produces higher weld speeds, while post-weld heat treatment is not considered necessary because of the superficial nature of the changes in the microstructure.