A mathematical model for the cathodic protection of tank bottoms

A mathematical model previously developed for predicting the cathodic protection of pipeline networks is extended to treat cathodic protection of the bottoms of cylindrical above-ground storage tanks. A single tank was modeled for which protection was provided by an anode located infinitely far from the tank bottom, by a series of anodes distributed around the circumference of the tank, and by an anode grid laid directly underneath the tank bottom. The influence of an insulating barrier associated with secondary spill containment was also modeled for the arrangements in which anodes are placed adjacent to the tank bottom. The performance predictions are strongly dependent on anode placement, the oxygen content of the soil, and the presence of insulating barriers associated with secondary spill containment.