Low Pressure Plasma Spraying Process-An Economical Substitute for Laborious, Costly Plasma Weld Surfacing Process for Hardfacing Critical Components

At present critical components like steam turbine spindles and power plant valve components etc. are being handfaced (stellited) using Plasma weld surfacing process involving laborious post weld heat treatment and weld distortion etc. Again, plasma weld surfacing is quite expensive due to deposition of higher build up layer of about 3 to 5 mm of costly consumable (stellite powder). Low pressure Plasma spraying (LPPS) is an economical and productive substitute to conventional weld surfacing process and IS being attempted for various critical applications in developed countries. Since LPPS is a new process and the LPPS system (imported equipment cost approx. Rs. 2 Crores) is not available indigenously, WRI Is developing this facility to establish the LPPS technology for hard facing applications. This paper describes the new hard facing process, its capabilities, advantages, limitations and industrial applications with respect to conventional plasma weld surfacing and spraying process. The new LPPS facility being developed at WRI has also been discussed.