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Five Year Internal Inspections and MIC

July 07, 2017 David Spence Jump to Comments

The following is a guest blog from one of BuildingReports service members, Integrated Fire Protection. If you would like to contribute as a guest blogger, please contact marketing@buildingreports.com.

Your fire sprinkler system is a vital part of your overall life safety system. But, as with all mechanical equipment, your systems must be maintained in order to provide proper protection to your facilities and occupants.


Over time, your sprinkler system’s piping can age or wear, leading to the build-up of foreign material or corrosion. A Five Year Internal Inspection can determine whether your pipes contain microbiologically influenced corrosion (MIC), rust, or slime. Obstructions like these within the piping, valves, or other devices can interfere with the system’s ability to function, in some cases rendering it inoperable, which can endanger lives in the event of a fire.

Internal investigations are done at the system valve, riser, cross-main, and branch lines. If any corrosion or obstructions are found in these areas, appropriate action must be taken to ensure your fire sprinkler system is always at a peak state of readiness.

What is microbiologically influenced corrosion (MIC)?

Microbiologically influenced corrosion or MIC, is an electrochemical process involving bacteria that can accelerate previously occurring corrosion in both wet and dry-pipe fire sprinkler systems.

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.

What are the warning signs that I have 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.

Code Reference

NFPA-25 (2011 edition) 14.2.1 states: “An inspection of piping and branch line conditions shall be conducted every five years by opening a flushing connection at the end of one main and by removing a sprinkler toward the end of one branch line for the purpose of investigating for the presence of foreign organic and inorganic material.”

Complying with NFPA: 25 Five Year Internal Inspections can assure these components function properly in case of a fire.

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