The development of creep damage diagnosis system for the high temperature steam pipes of the boiler in thermal power plants

The diagnosis system is able to observe directly the high temperature pipes of the boiler, recognize automatically creep damage, and determine the residual life on site employing a small laser microscope developed for this purpose. To be concrete, the weld-heat-affected zone is directly observed through the laser microscope, and the data are introduced into the image processing unit and the creep voids are automatically recognized. The area of the recognized voids is calculated in the process. Approximately 50 fields per diagnosis area (1mm ) are automatically observed, without an overlapping at the boundary of images. The void area ratio is then calculated. The residual life is instantly evaluated. With this system, a diagnosis time can be drastically reduced and repairs quickly could be made. This system will contribute to extend the service lives of equipments, which in turn will reduce power generating cost. Moreover, an improved reliability can be expected as a result of the proper preventive maintenance.