1994 年 43 巻 484 号 p. 107-113
Thermal power plants are now operating on a DSS or WSS basis in response to electricity supply and demand. This tends to increase the pump start/stop frequency and operation time in the low flow rate range so that the crack is possibly initiated. Therefore, the boiler feed water pumps can be maintained in stable operation if more accurate inspection techniques for maintenance and control are employed. In this study, three sophisticated nondestructive inspection techniques that are sensitive to fatigue damage have been utilized. They are: 1) X-ray diffraction method to detect damaged microstructure before crack initiation, 2) short crack detection by image processing of surface structure and 3) potential drop method to detect surface crack configuration. Those techniques are packaged as a system with a specially designed mechanical scanner for the pump shaft. The system has been applied to more than 200 actual pump shafts in a factory during in-service inspection.