Investigation of watergas welded joints for future decisions concerning old hydropower stations

After 60 years of service the watergas welded shaft of Kaprun hydropower plant was dismantled. In this work the results of the investigation of this weld are presented. Additionally to strength, hardness and toughness values obtained from standard small scale samples, some integral samples including welding flaws and inhomogenities were tested to verify the fracture mechanical assessment of the shaft. As an overall result it can be reported that the joint itself shows excellent behaviour similar to the base material as long as it is free of defects.