Quantitative evaluation of effective factors on flow accelerated corrosion. Part. 4. Evaluation of wall thinning profile in piping elements

Flow Accelerated Corrosion (FAC) is a pipe wall thinning phenomena to be monitored and managed in power plants with high priority. At present, its management has been conducted with conservative evaluation of thinning rate and residual lifetime of the piping based on wall thickness measurements. For future revision of the management, modeling of quantitative prediction method of FAC is being required. In previous study, authors have proposed a FAC model equation mainly consisted of iron solubility and mass transfer coefficient, which showed qualitative performance, but not in a quantitative manner. Therefore, the mass transfer coefficient equation was revised by adjusting Reynolds number dependency and by introducing new diffusivity model, which resulted with considerable improvement in prediction of FAC test data. This method was applied to evaluate relative susceptibility of FAC, i.e. 'Geometry Factor', and local FAC profile of piping elements, such as elbows and orifices, by parametric numerical calculations of the flow field in each element. Among the analyzed elements, glove valve was evaluated with the highest geometry factor, which matches with the deal in the JSME rules on pipe wall thinning management. (author)