CORROSION CONSEQUENCES OF SECONDARY OXIDATION OF MICROBIAL CORROSION

Microbial corrosion scenarios based on the action of sulfate-reducing bacteria (SRB) under disbonded tape coatings on the outside-of gas pip elines have been described previously. Secondary oxidation of these si tes leads to formation of unique corrosion products. These have been a ssociated with serious corrosion damage in the field. Laboratory studi es were performed under simulated field conditions on an iron sulfide- steel (FeSx-Fe) galvanic corrosion cell sustained by anaerobic microbi al activity. The effects of transitions from anaerobic to aerobic cond itions on corrosion rates were documented. Results were correlated wit h field observations, and potential mechanisms were discussed.