Abstract
Biofouling countermeasure evaluations have been conducted on C70600, Alclad 3003 and titanium tube material in natural seawater. The effectiveness of chemical and/or mechanical cleaning methods in controlling the growth of microbiological and corrosion product films has been determined by heat transfer resistance measurements. Concurrently, the effect of cleaning methods on the corrosion performance of C70600 and Alclad 3003 has been evaluated.
Aggressive cleaning by daily injection of chlorine and sponge rubber balls was found to successfully maintain a near zero heat transfer, or fouling, resistance for all three materials. Such methods were, however, detrimental to the corrosion performance of C70600 and Alclad 3003.
The corrosion resistance of both C70600 and Alclad 3003 in seawater depends on the formation of protective corrosion product films. Optimized cleaning methods were devised based on heat transfer measurements to minimize mechanical cleaning and its distruptive effect on film formation. Cleaning was performed only as required to maintain the fouling resistance within an acceptable range. Such optimized cleaning methods were found to provide effective control of fouling resistance without accelerating corrosion rates on C70600 and Alclad 3003. Because of its inherent biofouling resistance in seawater, C70600 required less frequent ball cleaning than Alclad 3003 or titanium to successfully maintain an equivalent range in fouling resistance.
