Open welding heads were conceived as a tool for orbital TIG welding with or without filler wire. The diameters of the tubes to be welded range from 8 mm up to 275 mm (ANSI 5/16″ to 11″). Open welding heads of the U-type are equipped with a TIG-torch with gas diffuser. Excellent gas protection is achieved in the zone around the torch, which is covered by the shielding gas streaming out of the gas lens. During the welding process, the arc and wire impact can be observed and controlled directly by the operator. The asymmetrical design of the open heads allows welding to be carried out at a very short distance to a wall or bend. The positioning of the welding torch can be carried out manually or by means of motorised slides: Arc Voltage Control (AVC) and torch oscillation (OSC).