Manufacturing Challenges for Hot Isostatic Pressing Large-Scale Vessels

Abstract Hot Isostatic Pressing (HIPing) has been used by Rolls-Royce to successfully manufacture nuclear plant components such as: valves, piping, and pump casings, the majority of these components being manufactured from stainless steels, typically 316L. There are potential benefits to be gained by manufacturing large nuclear plant pressure vessels via the HIP process, such vessels commonly being manufactured from Low Alloy Steel (LAS) materials such as ASME SA-508. HIPing of large-scale LAS structures present specific challenges. This paper presents the challenges Rolls-Royce has experienced in their HIP vessel development work and means of addressing those challenges. It covers key steps of the HIP manufacturing process, from powder production, through can manufacture including leak detection and HIP consolidation. Of particular note are the risks of powder oxidisation and contamination, achieving the necessary material toughness, and can failure during the HIP cycle as a consequence of poor can design and fabrication. The paper shows examples of the results of failures, e.g. contaminated and unconsolidated powder, and how the risk of such failures can be reduced.