This study considers a porcelain-enameled water heater tank. Protective current was calculated from coating efficiency and circuit resistances. The current required for cathodic protection (CP) of an actual tank was determined invarious waters. The potential distribution was measured. Good correlation occurred between tests on small specimens and actual tanks. There was good agreement between open-top and closed-top tanks. Anode resistance was lower than the structure resistance and was comparable to electrolyte resistance. Water heater CP is complex and needs careful design to achieve optimum results.
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