Microbiologically Influenced Corrosion (MIC)

Definition - What does Microbiologically Influenced Corrosion (MIC) mean?

Microbiologically influenced corrosion (MIC) is metal deterioration as a result of the metabolic activity of various microorganisms.

This corrosion is promoted or caused by microorganisms, typically chemoautotrophs. This type of corrosion applies to non-metallic objects as well as metals. For instance, aerobic bacteria such as acidithiobacillus thioxidants can cause significant corrosion as it serves as a factor in biogenic sulfide corrosion.

Microbiologically influenced corrosion is also known as biological corrosion and microbial corrosion.

Corrosionpedia explains Microbiologically Influenced Corrosion (MIC)

There is a wide range of bacteria in water known to provoke MIC in such materials as:

  • Stainless steel
  • Carbon steel
  • Copper alloys
  • Aluminum alloys
Such bacteria can be both aerobic and anaerobic. For instance, sulfate reducing bacteria (SRB) is considered to be accountable for many instances of hastened corrosion to offshore steel as well as ships, although it only exists in stagnant, deep water. In surface sea water, other specific types of micro-organisms are responsible for catalyzing the reduction of oxygen in the biofilm, leading to the formation of hygrogen peroxide. These are typically related to accelerated corrosion pitting attacks involving stainless steel.

Various industries that are affected by this type of corrosion include:

  • Offshore and onshore gas and oil industries
  • Waterflood and mothball systems as well as gas and oil handling systems
  • Industries related to chemical processing: flanged joints, tanks made of stainless steel, specifically in welded portions
  • Water treatment facilities such as piping and heat exchangers
  • Metal working facilities where increased wear, emulsions and machining oils may be present
  • Nuclear power plants with stainless and carbon steel tanks and piping as well as aluminum bronze and brass cooling tubes
MIC can be prevented through:
  • Periodic mechanical cleaning
  • Chemical treatment using biocides to prevent bacteria population
  • Dry storage and total drainage

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