Evaluation of Wall Thinning Rate due to Flow Accelerated Corrosion with the Coupled Models of Electrochemical Analysis and Double Oxide Layer Analysis

摘要

Wall thinning due to flow accelerated corrosion (FAC) were calculated with the coupled models of static electrochemical analysis and dynamic double oxide layer analysis. Anodic current density and electrochemical corrosion potential (ECP) were calculated with the static electrochemistry model based on an Evans diagram and ferrous ion release rate determined by the anodic current density was applied as input for the dynamic double oxide layer model. The thickness of oxide layer was calculated with the dynamic double oxide layer model and then was applied as input for the electrochemistry model. It was confirmed that the calculated results of the coupled models resulted good agreement with the measured ones. Higher ECP was essential for preventing FAC rate. Moderated conditions due to lower mass transfer coefficients resulted in thicker oxide layer and then higher ECP, while moderated corrosion conditions due to higher oxidant concentrations resulted in higher ECP.