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What is MIC? – Common Questions Answered

Wednesday, March 25, 2015

What is microbiologically influenced corrosion (MIC)?

Microbiologically influenced corrosion or MIC, is an electrochemical process which involves bacteria that can accelerate previously occurring corrosion in both wet- and dry-pipe fire sprinkler systems. MIC always involves bacteria but MIC never occurs by itself.

What causes corrosion in fire sprinkler systems?

Wet and dry fire sprinkler systems are primarily composed of metal pipe, water, and trapped or compressed air. Any environment which has oxygen, metal, and untreated water in prolonged contact with each other is subject to corrosion (e.g. rust). Bacteria and other corrosion mechanisms can accelerate and concentrate previously occurring corrosion in fire sprinkler systems.

What causes pinhole leaks in fire sprinkler systems?

Pinhole leaks can be caused by a variety of corrosion mechanisms. Though mostly attributed to MIC in fire sprinkler systems, pinhole leaks can also be a result of oxygen differential cell or under-deposit corrosion.

Where does MIC occur in fire sprinkler system?

MIC can occur anywhere in a fire sprinkler system that provides an environment favorable to bacteria colonization. Bacteria must obtain food (eat), mature (grow), exchange gases (breathe), excrete (dispose of waste) and reproduce (multiply). Unfortunately, this type of environment may exist in a variety of places within a fire sprinkler system.

What are the warning signs that I have microbiologically influenced corrosion or MIC?

Obviously leaks and obstructions would be potential indicators of MIC or other fire sprinkler system corrosion problems. However, discolored or foul smelling water along with evidence of tubercles and/or deposits on the interior of the pipe wall are also indications of corrosion activity.

Worried about MIC? Contact Ahern to learn more or set up a system inspection!

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