Influence of fouling on the efficiency of sacrificial anodes in providing cathodic protection in Southeast Asian tropical seawater

Abstract

Aluminum and zinc based sacrificial anodes are routinely used to provide corrosion protection to metals (typically steel) exposed to seawater, for example in steel pipelines and storage tanks. However, the high fouling rates experienced in South East Asia means that both the anodes and the metals to be protected rapidly become coated with macrofoulers, which could potentially prevent the anodes from being effective. The present study, involving exposure tests of up to 18 months, indicates that both aluminum and zinc sacrificial anodes remain effective even after being completely coated with biofouling. Furthermore, it was easier to remove the biofouling on the cathodically protected samples than on their unprotected counterparts, possibly due to the higher local pH produced by cathodic protection at the metal and seawater interface.

Keywords:

• cathodic protection
• tropical seawater
• corrosion

Acknowledgements

This work was jointly funded by the Defence Science & Technology Agency (POD 0411835) and the US Office for Naval Research (N00014-04-1-789). The authors would also like to thank CPtech Pte Ltd for providing the sacrificial anode materials and the Republic of Singapore Yacht Club for allowing the use of their marina.