Evaluation of the Effect of Paint Degradation on Shipboard Impressed Current Cathodic Protection Performance: A Physical Scale Modeling Approach

Physical scale modeling (PSM) has been used to evaluate and design shipboard impressed current cathodic protection (ICCP) systems in several NATO countries. With the application of numerical modeling techniques for the evaluation of shipboard ICCP performance, efforts to validate numerical modeling results using PSM data have been gaining increasing importance. As part of the efforts, a discrete area current control (DACC) technique was developed in previous studies to simulate the polarization resistance behavior of multiple cathodes including nickel aluminum bronze propellers and paint damage areas under a variety of conditions. The application of the DACC technique facilitated the use of identical polarization resistance data as boundary conditions for both PSM and numerical modeling analyses in the validation studies. In the current work, the DACC technique was extended to simulating polarization resistance behavior of various paint degradation scenarios (with polarization resistances varying from 1×10⁷ Ωcm² to 2×10⁵ Ωcm²) to study the effect of paint degradation on the performance of a shipboard ICCP system. The results indicated that overall paint degradation does not significantly affect the hull potential profile until the magnitude of the polarization resistance of the paint coating decreases below 1×10⁷ Ωcm². The PSM profiles were also compared with numerical modeling data acquired using a boundary element code resulting in a good agreement between the two techniques. The discrepancies observed between the PSM and numerical modeling profiles have also been discussed.