Evaluation of perfect paint assumptions in modeling of cathodic protection systems

Abstract

Computational modeling often involves making assumptions; assumptions about geometric features, material characterizations or loading conditions. The validity of these assumptions will directly impact accuracy. It is an accepted practice in computational modeling of impressed current cathodic protection (ICCP) systems to define painted surfaces as perfectly insulated (‘perfect paint’). While many paint systems have a high resistance, the resistance is finite rather than infinite. In this work, painted surfaces are defined with varying material properties ranging from relatively high resistance (0.0001 of the polarization response of steel) to relatively low (steel). These different material properties are assigned to the painted surfaces of a previously validated shipboard ICCP system model. All other boundary conditions are held constant. A comparison of results quantifies the effects of large but finite paint resistance on computational results and validates use of the perfectly insulated surface assumption for painted surfaces.