Corrosion and biofouling on stainless steels in Baltic sea water environment: a cooling water pilot study

In power plants, a reliable operation of the cooling water circuit is of primary importance. Where natural water is used for cooling, corrosion and biofouling may pose challenges to materials integrity. The brackish water in Baltic sea is characterized by a relatively low salt content and unique microbial communities, thus the material challenges may be different from those occurring in sea water. In this study, biofouling on and corrosion behaviour of stainless steels AISI 304L (EN 1.4307), AISI 316L (EN 1.4404) and 254 SMO (EN 1.4547) were investigated in a pilot scale cooling water circuit using brackish water of Baltic sea, obtained from Tvärminne zoological station. The pilot was in operation for 8 weeks, during which open circuit potential recording (OCP) was performed. Other electrochemical methods, cyclic anodic and cathodic polarization measurements and electrochemical impedance spectroscopy (EIS) were applied before and at the end of the pilot experiment. The biofilm coverage was calculated on surfaces. In this paper the obtained results are presented and discussed.