Cathodic protection for disks of various diameters

Abstract

In a simplified disk model for cathodic protection, the maximum disk size that can be protected completely is calculated for the case that the anode is infinitely far away. Results calculated for potential-dependent hydrogen evolution and iron dissolution are compared with that for an assumed uniform current density and an allowed window of variation of electrode potential. Attempting application of a voltage that yields equal average hydrogen and iron current densities leads to iron corrosion near the center and hydrogen generation near the edge of the disk, with large values of these current densities for large disks. Another approach is to suppress only iron corrosion by applying a sufficiently negative protecting voltage. Suppressing the iron current leads to an enormous hydrogen generation near the edge of large disks. (C) 2001 The Electrochemical Society. All rights reserved