Weldability of additive manufactured pipe features for fusion component replacement

The current strategy for joining ITER divertor cooling pipes is to conduct semi-automated autogenous Tungsten Inert Gas (TIG) welding on thin-walled pipes using an inserted flat washer filler ring. In this approach, the positioning of the filler ring and the alignment of the pipe stubs so far can only be achieved manually. However, it has limitations for future maintenance because human interventions may be limited or completely prohibited in contaminated environments, requiring the need for remotely operated tools and systems. In addition, maintenance of cooling pipes will involve cutting and re-welding of the parts. However, components have limited lifespan for reuse. Additive manufacturing (AM) is an advanced technique that provides one potential way to overcome the limitations. This work investigates the use of the AM method to deposit material as an alternative approach to using filler rings, which a flange feature was firstly built on the pipe end using laser blown powder direct energy deposition (DED). Thereafter, semi-automated autogenous TIG welding was conducted on the AM modified pipe stubs. The results suggest that using the AM produced parts has achieved compliant pipe joins, implying possible improvements to maintenance strategies for future fusion power plants and experimental devices.