Determination of the Possible Causes of Cracks in Pins of Quick Operating Valves in Hydroelectric Power Plant

During the revision of the individual parts of a hydroelectric power plant the cracks in the pins of quick operating and revision flap valves of Francis turbine were found. Our department has been approached with a request to investigate the causes of these cracks. This paper deals with the complex analysis of influential factors, especially the measurements of residual stresses by hole-drilling method, in order to reveal the factors causing the cracks in the pins.