In High Frequency Welded (HFW) pipe production process, hot rolled steel coils are fed with a high capacity accumulator in order to achieve continuous welding. Coil edges are milled using carbide cutters in order to assure a high quality weld. Coils are then formed by cold forming method using a set of cage rolls and fin passes, and then joined using high frequency currents using induction or alternatively conduction methods.
The coil edges, which reach welding temperature through the resistance shown by steel to the applied electrical current, are butted together and welded. This method does not use any filler material for the weld to take place. Immediately subsequent to welding, internal and external burrs are removed in order to achieve a uniform surface.