Amod Panthee
Kathmandu University, Nepal
Title: Development of guidelines for welding repair of hydraulic turbines
Biography
Biography: Amod Panthee
Abstract
Turbine material is heavily eroded when operated in sediment-laden rivers in Nepal. Erosion reduces the efficiency and increases operational risk. The solution to these problems due to erosion is either to replace with new turbines or repair and operate. But, welding repair is chosen as best alternative in Nepalese energy industry due to low cost to build-up the eroded surface. Welding repair of hydraulic turbines does not impair the material property but it can be catastrophic when carried out improperly. Such problem is also observed in Khimti Hydropower (KHP) and Chilime Hydropower (CHP) in Nepal. The turbines in KHP and CHP operated without major defects before repair. But root cracks and cracks along the splitter was observed after welding repair. The occurence of cracks in welding repaired turbines is due to factors like quality of weld deposit, preheating and post weld heat treatment conditions and design changes during repair. Therefore, quality control in welding repair is essential to avoid such failures. The paper aims to discuss the current practice of welding repair and experimental study on mechanical properties of turbine material at various heat treatment conditions. The results thus obtained is used to develop a guideline for welding repair of hydro-turbines. The long term output of the project will be intallation of welding repair plant at local industry in Nepal for maintenance of hydro-turbines.