ABSTRACT
Cathodic protection is a method of controlling the corrosion of a metal structure by cathodically polarizing it to a potential more negative than its rest potential in a moist soil or aqueous environment. Cathodic protection is extensively applied to buried pipelines and distribution systems which must serve for many years with absolute reliability not only for the direct costs of capital investment, but also for consequential costs of disrupted supplies. Cathodic protection schemes are applied in great variety. The chapter summarizes the general principles, and illustrates how they are exploited in practice by reference to the basic applications: the protection of buried pipelines and distribution systems, and the protection of ships and steel structures exposed to open waters. The general criterion for commissioning and monitoring a cathodically protected system is that the potential difference between a protected structure and its environment satisfies the theoretical requirements implicit in the design.
