Microbiologically influenced corrosion: attack driven or accelerated by microbes living in biofilms on the metal. Sulfate-reducing bacteria produce hydrogen sulfide and iron sulfide, acid producers lower the pH, and iron-oxidizing bacteria build tubercles that shelter aggressive cells underneath. MIC shows as clusters of pits, often with black deposits, in stagnant water lines, tank bottoms, fire sprinklers and piping where hydrotest water was left standing.
Hydrotest water sat in that line six months, now there's MIC pitting at every low spot.
Never leave untreated hydrotest water standing in a new line. Drain and dry it promptly or treat it, because stagnant water is a classic MIC starter.
Also heard as
- microbial corrosion
- biocorrosion
Related terms
SRB
Sulfate-reducing bacteria: oxygen-free microbes that make hydrogen sulfide and drive much MIC.
Bugs
Field slang for the bacteria behind microbiologically influenced corrosion and system souring.
Bug bottle
Field nickname for the serial dilution culture vials used to count bacteria in water samples.
Tuberculation
Growth of knob-like mounds of rust and deposits on the inside of iron and steel water pipes.
Pitting
Localized corrosion that drills small, deep cavities into metal while the surface around them stays nearly intact.