Microbiologically Influenced Corrosion (MIC) of Mooring Systems: Diagnostic Techniques to Improve Mooring Integrity

Microbiologically Influenced Corrosion (MIC) is the term used to describe corrosion where the presence and activity of microorganisms accelerates the corrosion rate or modifies the mechanism of corrosion. MIC is strongly associated with the high rates of localized pitting corrosion observed on moorings installed in some offshore fields, including fields in West Africa and South East Asia. Diagnosis of MIC in the field can be problematic, and is largely reliant on visual inspection and microbiological reactivity tests, techniques that are limited in their accuracy and reliability. As a result, other forms of corrosion and wear can be easily misdiagnosed as MIC, with potential negative consequences for the subsequent management of the integrity of the mooring system. This paper presents an overview of the most recent research regarding factors influencing rates of conventional corrosion and MIC (as determined within the SCORCH JIP). It describes recent advances in the application of functional genetic and chemical analysis techniques to diagnose MIC, improve understand of the biochemical processes causing MIC, and identify pathways to interrupt and mitigate MIC on mooring components.