Wall-Thinning Analysis of the Pipelines in the Secondary Section of NPP Available to Purchase

Wall-thinning investigation of three carbon steel pipe samples from secondary section of nuclear power plants has been carried out in this paper. The operating conditions of the three pipe samples are quite different, which leads to the different wall-thinning reasons and characteristics of the pipes. The chemical compositions of the steel materials, the stereomicroscope examinations, SEM examinations, as well as the XRD analysis are performed. The results show that: The wall-thinning of No.1 elbow was caused by erosion corrosion; the wall-thinning of No.2 elbow was caused by flow accelerated corrosion; the wall-thinning and crevasse of No.3 orifice plate was caused by cavitations. Measures to solve the wall-thinning problems of different pipes are also given in this paper.