The ITER project represents a unique challenge for the assembly of workpieces, particularly on site, due to required precision after assembly and the quality (zero defects). Narrow Gap TIG Hot Wire welding appears as one of the essential techniques for joining these kinds of parts with such large wall thicknesses, as far as on-site assembly is concerned. This welding process corresponds perfectly to the constraints involved in the final assembly.
Polysoude develops two main technological approaches: By fixed electrode torch and by oscillating electrode torch. The first technique meets productivity requirements for preparation of joints with perfectly defined tolerances. The second technique satisfies the necessity for maximal flexibility in order to compensate tolerances of the workpiece end preparation and shrinkage during welding. The “torch carriers” such as robot, boom and carriage-type welding heads are tools which are adapted to the size and geometry of the joint to be welded.
It is realistic to consider using Narrow Gap TIG to weld workpieces up to 400mm thick given the numerous relevant advantages. This technology can be adopted in all areas of industry such as the construction of equipment for energy (hydro-electric, conventional fossil fuel and nuclear power plants), petrochemical and manufacture or repair of heavy wall pipes.
