Configuration Design Development of Internal Bore GTAW Welding

Abstract

The cooling water lines operating in vacuum and nuclear environment being a crucial component subjected to high pressure, welding is of utmost importance from the perspective of their through thickness integrity, and therefore, the full penetration butt welding is the mandatory requirement. However, in complex geometries like high-voltage bushing for neutral beam systems for fusion devices, the cooling pipes are so closely spaced that the welding from outside is not feasible by orbital welding technique. For this and similar systems, there is a need to have an alternative tool development, wherein the welding arm goes inside the pipe, reaches to the location of weld edge preparation and produces the arc such that the penetration is produced on the outer circumference of pipe. Such a technique, known as ‘Internal Bore Welding’ (IBW), is proposed here. IBW torch is being designed to work with the wide range of pipe diameter with varying arm length to weld at different length locations. The minimum pipe size considered for the torch design is 25.4 mm. In order to give the rotation, precision motors have been used, and to avoid the interference on the electric and shielding gas supply connections, non-axial motion transfer has been designed with gear connections.