Application of Potential Drop Technique to the Inspection of Welded Boiler Pressure Parts

Abstract

In this paper, a practical method using the electrical potential drop technique was discussed to evaluate the creep damage accumulated in the welded power piping such as main steam pipe and hot reheat pipe. Round robin experimental measurements conducted by the authors et al. as academic activities in the Japanese Society for Non-destructive Inspection showed that the potential drop technique is effective for the application to the inspection of welded boiler pressure parts. The authors have conducted additional experimental and numerical studies for verification focusing on the application of the pulsed direct current potential drop technique. The authors have proposed technical requirements on the potential drop technique for the application to the inspection of welded power piping to be implemented in JSME Codes for Thermal Power Generation Facilities (2003 Edition) as a non-mandatory appendix JA. And the practical on-line measurement in the high temperature and high pressure burst test using the repair-welded power piping has been conducted. In this burst test, Tokyo Electric Power Company has tried to monitor the creep damage accumulated in the seam-welded area using the commercialized tool based on pulsed direct current potential drop technique.