Advanced Prediction Model for Pipe Wall Thinning Tendency by Flow Accelerated Corrosion at Junction Piping

Abstract

Flow Accelerated Corrosion (FAC) is a pipe wall thinning phenomenon to be monitored and managed in the power plants with high priority. Its management has been conducted with conservative evaluation of thinning rate, and residual lifetime of piping based on wall thickness measurements. However, noticeable case of the wall thinning occurred in branch and junction piping (tee tube). There is a problem to manage the wall thickness beneath reinforcing plate of the tee tube, because measurement of this area is difficult to be conducted with ordinary ultrasonic testing devices due to the presence of the reinforcing plate. In this study, numerical analysis for the tee tube was conducted, and the wall thinning profile due to the FAC was evaluated by calculating the mass transfer coefficient. It was found that a localized wall thinning distribution occurs in the area where the reinforcing plate of the tee tube exists. And this tendency is affected by Reynolds number. In previous studies, a model was introduced to predict this trend, but in this study, the model was improved to take into account the effect of the Reynolds number.