51312-01246-Study of MIC impact in a full-scale ship ballast tank

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Product Number: 51312-01246-SG

ISBN: 01246 2012 CP

Author: Anne Heyer

Publication Date: 2012

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A. Heyer1 F. D’Souza2 G. Ferrari2 F.S.L. Marty3 G. Muyzer3J.M.C. Mol4 and J.H.W. de Wit4 1M2i Materials innovation institute Mekelweg 2 2628 CD Delft The Netherlands a.heyer@m2i.nl2TNO Bevesierweg 1781 CA Den Helder The Netherlands fraddry.dsouza@tno.nl G.Ferrari@quicknet.nl3Environmental BiotechnologyDepartment of Biotechnology Delft University of Technology Delft The Netherlands F.S.L.Marty@tudelft.nl G.Muijzer@tudelft.nl 4Delft University of Technology Department of Materials Science and Engineering Mekelweg 2 2628 CD Delft The Netherlands j.m.c.mol@tudelft.nl j.h.w.dewit@tudelft.nlMicrobiologically influenced corrosion (MIC) of steel is a serious problem in the marine environment and many industries such as the shipping industry. Under natural conditions biofilms form heterogeneous patchy surfaces which will result in pitting corrosion. While electrochemical measurements such as impedance measurements have been used in corrosion monitoring for many years the true capabilities of the technique and the optimal methods for extracting useful information from the collected data combined with microbiological techniques are now becoming clear. A new approach was made by using an experimental full-scale ship ballast tank (SBT) to study the impact of MIC. Working electrodes were immersed at two different height levels of the SBT (bottom and immersion zone) to model the corrosion behavior of ASTM A131 Steel grade EH36 exposed to natural seawater in these specific zones. Until now little information is available on microbial community composition and the corresponding corrosion rates within ship ballast tanks. To overcome this lack of information biofilm samples were taken from exposed corrosion coupons and PCR-DGGE analysis was performed to characterize the microbial community on the sidewall of ship ballast tanks as well as the water phase. Additional fluorescent staining in liquid allowed monitoring biofilm development and pit formation. This information was combined with conventional electrochemical measurements on site as OCP LPR and EIS to evaluate corrosion initiation by bacterial communities in closed seawater environments like ship ballast tanks. Substantial corrosion could be monitored by EIS indicating a clear difference in corrosion rates for bottom and immersion zone related to the variation of bacterial species. Keywords: ship ballast tank MIC biofilm LPR PCR