Corrosion in Automatic Sprinkler Systems: FM Data Sheet 2-1 Update

Posted by Experts in Nitrogen Generators and Automatic Air Vents on Dec 2, 2016 11:50:14 AM

FM Global recently released a revised Data Sheet 2-1 entitled Corrosion in Automatic Sprinkler Systems. It has been approximately 15 years since the previous release and the new Data Sheet provides fundamentally different recommendations regarding the management of corrosion in fire sprinkler systems. While the previous data sheet focused primarily on Microbiologically Influcenced Corrosion (MIC), the new version recognizes oxygen as the primary cause of corrosion and nitrogen inerting as the recommended solution.

The new Data Sheet is a complete endorsement of the practices that ECS has been promoting for the past eight (8) years. ECS nitrogen generators and wet system vents are FM Approved and ECS has the longest track record of successful deployment of Dry Pipe Nitrogen Inerting (DPNI) and Wet Pipe Nitrogen Interting (WPNI) in fire sprinkler systems.


Here is what the OLD FM Global Data Sheet 2-1 (2001) included:

  • Focused on Microbiologically Influenced Corrosion (MIC) as the cause of leaks in fire sprinkler systems
  • Test supply water for nutrient loading for MIC and for the presence of MIC causing bacteria SRB and IRB
  • Treat supply water and existing contaminated systems with disinfectant or a microbicide
  • Datasheet provided a complete protocol for cleaning existing fire sprinkler pipes
  • Use MIC testing kits to measure contamination levels in the supply water and in the sprinkler piping
  • Use non-destructive ultrasonic measurement techniques to determine metal loss in existing fire sprinkler systems

Here is what the NEW FM Global Data Sheet 2-1 (October 2016) includes:

  • Oxygen in fire sprinkler systems drives the corrosion chemistry within metallic fire sprinkler piping
  • Install an FM Approved vent on wet pipe systems to remove trapped air to prevent oxygen corrosion – this reinforces the new NFPA 13 requirement for the use of an automatic vent on all wet pipe systems
  • Pressurize dry and preaction systems with an FM approved nitrogen generator or nitrogen cylinders – if the client chooses not to use nitrogen there are nine (9) system enhancements that must be done in lieu of nitrogen
  • In dry pipe systems constructed of galvanized steel piping complete failure can occur in 2-3 years when there is trapped water in the system piping – use nitrogen gas as pressure maintenance gas
  • Black steel is acceptable in dry and preaction systems when used with nitrogen gas
  • Use borescope and failed pipe sampling to determine corrosion leak risk in fire sprinkler systems; ultrasonic testing is not recommended
  • Detecting MIC in the system does not necessarily mean that corrosion damage from MIC has occurred
  • MIC causes only 10-20% of fire sprinkler leaks, MIC is not a major contributor
  • Do not use chemical cleaners or corrosion inhibitors
  • Chemical treatment for MIC is not recommended because it can accelerate pipe corrosion

Automatic Air Vent at ECS

Engineered Corrosion Solutions believes that educating the fire sprinkler industry about the risks associated with corrosion is imperative as fire sprinkler systems continue to age and degrade. The release of FM Global's updated Data Sheet is another positive step towards a fully informed industry.

A full list of FM Global Data Sheets can be found at their website linked here.

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Tags: MIC, FM Global