Current Distributions in Galvanically Coupled and Cathodically Protected Tubes

Current distributions inside galvanically coupled and cathodically protected tubes were calculated over a range of geometric, kinetic, and hydrodynamic conditions. Polarization expressions considered included linear, Butler-Volmer, and experimental expressions developed from laboratory data on rotating cylinder electrodes. By integrating the current densities over the tube area, the total current resulting from a galvanic couple was determined. From these calculations, correlations of the total current with geometric parameters, corrosion potentials, conductivity, and polarization resistance were developed. The correlations were applied in the design of cathodic protection systems for heat exchangers using untreated seawater. Use of these correlations to simplify large-scale numerical simulations of steam condensers was demonstrated.