Failure analysis of hydraulic turbine shaft

► Failure analysis of a 28 MW hydraulic turbine shaft. ► Lack of corrosion protection lead to corrosion fatigue failure of turbine shaft. ► Corrosion fatigue cracks due to river water leakage through the sealing box. ► High stresses during start/stop cycles in the critical radius for “wet” environment. This paper describes the analysis of major failure of 28 MW horizontal hydro turbine shaft. The analysis of load carrying capacity of critical radius and fractography analysis are presented. Special emphasize is on metallurgical failure analysis of in-service crack initiation. The analysis of stresses is obtained by the finite element method and the developed model and load conditions are described. Finite element analysis is performed for case of normal service and start-up regime. Based on the failure analysis and numerical calculations, it could be concluded that the seal box design led to constant flow of river water in zone of critical radius which resulted as occurrence of corrosion fatigue cracks and major failure of turbine shaft. Suggestions for problem solution for the turbine shaft are also presented.