Key Parameters to Determine Wall Thinning due to Flow Accelerated Corrosion

摘要

In order to predict occurrence of flow accelerated corrosion (FAC) and to estimate wall thinning rate due to FAC, six step calculation procedures have been proposed. In the procedures, FAC is determined by six parameters, i.e., the flow dynamics parameter, chromium content in materials, temperature, pH, oxygen concentration, and ferrous ion concentration ([Fe~(2+)]) in bulk water. The high FAC risk zones were evaluated by the maximum wall thinning rates, which were determined by a function of ID FAC parameters. At the indicated high FAC risk zone, 3D distributions of mass transfer coefficients were obtained and then wall thinning rates were calculated with the coupled model of static electrochemical analysis and dynamic oxide layer growth analysis. In the paper, the effects of all parameters except that related to [Fe~(2+)] on FAC occurrence have been discussed and then the effects of [Fe~(2+)] on wall thinning are discussed.