Experience in the ultrasonic testing of fastening studs in the covers of hydraulic units at hydroelectric power plants

The criteria for evaluation of the admissibility of discontinuity flaws under the threads of studs during their inspection from the end face without unscrewing them from their seat in a hydraulic unit frame are experimentally substantiated. A transducer with the optimal parameters that allows one to reveal cracks of minimal depths is selected. Ultrasonic inspection of studs with a hexahedron at the end face is used as an example and the results of the ultrasonic testing of studs with detected cracks are presented.