An Innovative Method for Rapid Detection of Microbiologically Influenced Corrosion.

Microbiologically influenced corrosion (MIC), the interaction of biological activity with corrosion processes, is a significant cause of degradation of piping and heat transfer surfaces in cooling water systems. MIC can produce localized corrosion and through-wall penetration of piping and heat exchanger tubing at rates 10 to 1000 times more rapid than those normally encountered. Monitoring of biofilm formation on line provides the system operator with the information needed to initiate mitigation activities, such as cleaning and water treatment, well before the structural integrity of piping or Components is jeopardized. On-line monitoring of biofilms, and timely actions, taken before corrosion has initiated or thick biofilms are formed on piping or heat exchanger tube surfaces, can significantly improve the effectiveness of mitigation activities. Continuous monitoring of biofilm activity permits close control of biocide additions (to avoid over-treatment of the water) and scheduling of preventive maintenance activities so that Unplanned downtime due to MIC is avoided. The electrochemical aspects of MIC have been discussed by a number of authors 1-8. Since MIC affects electrochemical reactions that influence corrosion, biofilm activity may be tracked by electrochemical monitoring methods that are specific to those electrochemical reactions by which biofilms can influence corrosion. An electrochemical device, the BIoGEORGE(TM) probe, has been developed to provide a method for determining the onset of biofilm formation on metal surfaces and tracking biofilm activity on line in a power plant or industrial environment 9.

Presented at the Tri-Service Conference on Corrosion Held in Orlando, Florida on 21-23 June 1994. Prepared in cooperation with Corrosion Failure Analysis and Control, San Ramon, CA.