Managing soil-side corrosion problems on Above Ground Storage Tanks (AGSTs) presents an important challenge to refinery corrosion engineers. Cathodic protection and periodic internal inspection are two methods of managing soil-side corrosion. Mobil Oil Australia conducted a study into the need and feasibility of cathodically protecting up to 120 tanks at its Altona refinery in Melbourne Australia The need was determined by assessing the corrosivity of the environment under the tanks from soil samples and inspection data, and the feasibility determined by conducting current drainage testing on representative tanks. Results indicated that the tanks can be cathodically protected at less than 10mA/m2 current density, using perimeter anodes. They also showed that there is little correlation between bulk foundation or surrounding soil properties, and soil-side corrosion. The paper also demonstrates how the extension of intervals between internal inspections can economically justify the application of cathodic protection.

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