Microbiologically Induced Corrosion

Living organisms can promote corrosion in many different environments.A variety of biological organisms thrive in both aerobic and anaerobic environments. Corrosion attributable to microbiological activity occurs most frequently
in stagnant water, which remains in a centrifugal pump when it is shut down for an extended length of time.


Living organisms can promote corrosion in many different environments.A variety of biological organisms thrive in both aerobic and anaerobic environments. Corrosion attributable to microbiological activity occurs most frequently
in stagnant water, which remains in a slurry pump when it is shut down for an extended
length of time.


Several more serious types of microbiologically induced corrosion afflict stainless steels.A certain class of metal ion concentrating/oxidizing microbes appears to concentrate ferric and manganic chlorides, both of which are potent pitting agents. These bacteria form colonies preferentially at welds in austenitic stainless steels and are capable of causing severe pitting corrosion in a relatively short time. This problem has been encountered in a variety of equipment in both salt and fresh water. It is often discovered only when the
welds begin leaking. slurry Pumps employing welded stainless steel fabrications can be afflicted by this problem if permitted to sit idle with stagnant water, either fresh or salt, for an extended period. Biocides can be used to mitigate this problem in some instances.


Finally, the decay of biological organisms can generate hydrogen sulfide, which
adversely affects the protective oxide film on copper base alloys. The enhanced biological activity in warmer tropical waters, especially under stagnant conditions, can impair the corrosion resistance of bronzes and reduce the threshold velocity at which accelerated corrosion will occur. Bronzes should be used with caution in applications where macrobiological activity is anticipated and the possibility of extended shutdowns is possible.