a process for applying weld overlay material to a tube with a single pass of a weld head . a gas tungsten arc welding process with high frequency wave pulse current is preferably used to apply the overlay material . the overlay material is preferably in the form of weld wire and is pre - heated and mechanically fed into the resultant weld pool on the tube . the wire is preferably resistance - heated to a temperature lower than its melting point prior to contact of the wire with the molten weld pool , and the weld pool is preferably oscillated during the overlay process . use of the gas tungsten arc welding process provides sufficient weld fusion to allow the overlaid tube to be subsequently bent and formed , and use of the high frequency wave pulse current provides for reduced dilution of the overlay .