“CP Criteria & Application” Symposium

Paper Requirements

April 27, 2007 Deadline

Current and potential distribution modelling for CP of tank bottoms

Bruno Bazzoni°, Sergio Lorenzi°°, Paolo Marcassoli°°, Tommaso Pastore°°

°CESCOR, Milan

°°Dipartimento di Progettazione e Tecnologie, Università di Bergamo

ABSTRACT

Above ground tanks for storage of liquid hydrocarbon are often erected with secondary containment membrane in stalled below the tank bottom to prevent the soil contamination in case of leakage.

The design of impressed current cathodic protection in presence of the plastic membrane is based on distributed anodes installed in the space between the tank bottom and the membrane; among available anodes, the most commonly used are the titanium grid or ribbon activated with noble metal oxides.

The configuration of the grid or ribbon anode system confined in the closed space between bottom and membrane creates specific issues concerning the electrochemical reactions occurring at anode and cathode, the ohmic drops in the anode system and the potential and current distribution at the cathode.

The paper reviews the specific aspects of this application of cathodic protection and provides results of a number of numeric simulations performed to predict the actual distribution of current and potential.