An example of microbiologically influenced corrosion: The behaviour of stainless steels in natural seawater

Abstract

The aim of this paper is to summarize the most significant experimental data collected so far by our Institute on the corrosion behaviour of stainless steels in natural seawater. The purpose of the review is to illustrate the microbiological interference mechanisms with corrosion processes suggested by these experiments. The higher corrosivity of natural, as compared with sterile, seawater seems to be due to a change in oxygen reduction kinetics caused by the presence of microbiological slime on stainless steel surfaces. The observation that the accelerating effects occur only with biologically active slimes suggests the hypothesis of an enzymic catalysis affecting the oxygen reduction rates. The aerobic microbial slime components are confirmed to be the main cause of this effects. Any external action able to remove the slime physically or to inhibit its viability by toxics or by temperature rises affects the electrochemical phenomenon also.