In industrial installations where water plays a central role—such as cooling towers, storage tanks, piping systems, sprinkler systems, and water treatment installations—corrosion is a well-known issue. What is far less recognized is the role that microorganisms play in this process. Microbiologically Influenced Corrosion (MIC) is a stealthy but serious risk that can lead to accelerated damage to installations, often without visible warning signs.
What is MIC?
MIC, also known as biocorrosion, is a form of corrosion caused or accelerated by the presence and activity of microorganisms such as bacteria. This biological process primarily occurs in moist environments and affects metal materials such as steel (including stainless steel), copper, and aluminum.
MIC develops when microorganisms attach themselves to metal surfaces and form a biofilm. Within this layer, bacteria produce substances such as acids, slime, gases, and sulfides that attack the metal.
These processes result in localized and often invisible corrosion that is difficult to detect without targeted analysis. Unlike general corrosion, MIC often progresses rapidly and irregularly, making the damage unpredictable.
Which bacteria cause MIC?
The main microorganisms responsible for MIC are:
- Sulfate-reducing bacteria (SRB): Convert sulfates into hydrogen sulfide, a highly corrosive substance.
- Iron bacteria: Use iron as an energy source and cause deposits and metal degradation.
- Acid-producing bacteria: Produce acids that chemically attack metal surfaces.
- Slime-forming bacteria: Create dense biofilms that promote blockages and corrosion.
Why is MIC so dangerous?
MIC is difficult to detect because the damage is often hidden beneath biofilms or deposits. The first visible signs are often pitting (small holes in the metal), leaks, or pressure loss, but by then the damage is already significant. Moreover, traditional corrosion protection methods are often insufficient against MIC, as they focus on chemical rather than microbiological causes.
The process is usually localized, making structural risks hard to assess. In environments with stagnant or slow-flowing water, MIC can develop rapidly, causing severe damage within weeks to months.
How can you recognize MIC?
Watch for the following warning signs:
- Unexplained corrosion in unexpected locations
- Localized pitting (small holes) on metal surfaces
- Brown, black, or slimy biofilms
- Recurring problems despite regular corrosion control measures
Which sectors are at increased risk of MIC?
MIC occurs across a wide range of industrial sectors. In the oil and gas industry, pipelines and storage tanks are particularly vulnerable. Water treatment installations suffer from MIC in pipes, tanks, and cooling systems. In power plants, heat exchangers and cooling towers are risk points. The food and beverage industry, chemical industry, and pharmaceutical sector—where process and water purification systems are used—also face significant challenges from MIC.
Sprinkler systems and storage tanks for fire suppression water are at increased risk as well, due to prolonged periods of stagnation.
MIC often leads to increased maintenance costs, unplanned downtime, and sometimes the need to replace entire systems. A preventive approach is therefore essential.
Detecting MIC through water analysis
MIC requires a specialized and microbiologically based approach. At Ekopak, we have our own laboratory where we perform extensive water analyses, including BART tests (Biological Activity Reaction Tests). These tests detect the presence of microorganisms that cause corrosion and determine whether MIC is present.
Ekopak offers targeted solutions to control MIC and prevent corrosion in your installations.
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