The cathodic protection potential criteria: Evaluation of the evidence
Chris Googan
Abstract
Abstract Recent publications have ascribed the mechanism of cathodic protection (CP) in soils to the development of passivity at the steel surface. This view has, in turn, prompted discussion on the need to re‐evaluate the long‐established criteria for protection. This paper presents a contribution to that discussion. It advances, or rather it restates, the proposition that neither immunity nor passivity is necessarily relevant. It argues that protection is simply a consequence of a potential‐driven lowering of the anodic dissolution rate. However, it also emerges that elucidating any mechanism convincingly requires dependable field or laboratory data on the very low corrosion rates occurring on cathodically polarised specimens. A critical review of published data highlights a lack of reliability in this area.