Marine Corrosion

When microbes contribute to corrosion, it is known as Microbiologically Influenced Corrosion (MIC). MIC can affect most metals, including steel, aluminium, copper, and their alloys.

In marine systems, the primary corrosion mechanism often involves bacteria called Sulphate Reducing Bacteria. These bacteria reduce sulphate and produce corrosive hydrogen sulphide. The process through which induce corrosion is complex; it entails the formation of an iron sulphide film, which acts as a cathode to the steel beneath, as well as direct influences on electron flow, leading to the formation of pits.

Systems vulnerable to seawater ingress or those with seawater-compensated fuel tanks are particularly prone to MIC caused by Sulphate Reducing Bacteria due to the abundance of sulphate in seawater.

Microbiologically Influenced Corrosion (MIC) induced by Sulphate Reducing Bacteria is characterised by deep pitting. Pits may exhibit steep sides or saucer-shaped depressions; occasionally, they display terraced edges with a flat bottom containing additional smaller pits. MIC involving Sulphate Reducing Bacteria typically occurs at significantly faster rates than normal for steel exposed to seawater, typically resulting in an annual thickness loss of 1 to 3 mm.

Other mechanisms of Microbiologically Influenced Corrosion (MIC) include iron oxidising bacteria and the production of acids by microbes. For instance, fungal colonisation can lead to the corrosion of stainless steel heat exchanger plates.

 How ECHA can help with Marine Corrosion

• Perform material susceptibility assessments and analyse corrosion deposit samples from your vessel or facility in our UK laboratory to evaluate microbiological contamination extent and assess the risk of Microbiologically Influenced Corrosion. Discover more about our laboratory service.
• Supply on-board microbial Test Kits. ECHA’s Sig Sulphide test kit is suitable for on-site or laboratory use by non-microbiologists to detect Sulphate Reducing Bacteria.
• Conduct surveys of tanks and systems aboard your vessel or platform if Microbiologically Influenced Corrosion concerns arise. Learn more about our Site Surveys.

• Investigate corrosion incidents and offer guidance on remediation, control, monitoring strategies, and best practices. Find out more about our Consultancy Services.

• Deliver comprehensive, tailored training courses on microbiological contamination of marine fuels, including Microbiologically Influenced Corrosion.