September 2014 Luncheon Seminar – Nitrogen Inerting for Corrosion Control in Fire Sprinkler Systems

September 2014 Luncheon
The Chicago SFPE chapter meeting on September 8, 2014, was held at the Parthenon, at 314 S. Halsted in Chicago. The speaker was Jeff Kochelek, Chief Executive Officer with Engineered Corrosion Solutions.

Jeff gave a very interesting and detailed presentation with an overview of various assessment parameters used to manage and control corrosion-related risk in water-based fire sprinkler systems. He reviewed, the process to identify and recognize likely locations for corrosion to occur; reviewed the options for corrosion control; described Wet Pipe Nitrogen Inerting (WPNI) process, and Dry Pipe Nitrogen Inerting (DPNI) process.

A large part of Jeffs discussion was on the 6 myths regarding corrosion in fire sprinkler systems. These are listed below with a short description see the ECS website for more complete details:

  • Microbiologically Influenced Corrosion is the primary cause of pin-hole leaks in fire sprinkler systems. Oxygen gas is the primary cause as it removes metal from the pipe walls and creates insoluble by-products. Bacteria is always present but there is little correlation between the level of contamination and corrosion related leaks.
  • Galvanized Steel Piping Performs Better than Black Steel in Preventing Corrosion in Dry Systems.Galvanized piping in dry pipe systems can begin leaking 3-4X faster than black steel piping under similar conditions and costs more. Corrosion is very localized, as compared to black steel piping which is more dispersed.
  • Once a Fire Sprinkler System Starts to Have Frequent Pin-Hole Leaks, It Must be Replaced to Stop the Leaks.
  • Bad Water Causes Fire Sprinkler System Leaks.When systems are replaced, it is usually found that only 20% of the piping is significantly damaged by corrosion. Its more cost effect to remove the damaged piping and institute a comprehensive corrosion management system.
  • Pipe Material Defect Causes Weld Seam Failures.Almost all fire supply water comes from municipal sources is for the most part very fresh and clean. Water chemistry does vary but in general it is the introduction of oxygen into the piping that causes increased leaking, not the quality of the supply water.
  • The Quality of Fire Sprinkler Piping and Fittings Has Declined.Failed piping that shows evidence of material defect from the manufacturer is very rare. Corrosion at weld seams is often recognized as the cause of leaks but is not the result of defective piping. When wet pipe systems are drained and refilled frequently they will develop more leaks. When pressure maintenance compressors run more frequently on dry and preaction systems they will develop more leaks. Removing the oxygen and preventing its introduction by inerting the systems with nitrogen can completely stop corrosion.
  • See the link for a more detailed discussion on this topic. Many of us attending found this presentation useful, as it helped demystify some aspects of sprinkler piping corrosion problems.

    Go to the website, www.ecscorrosion.com, for several white papers on the subject, product specification sheets, FAQs for General Fire Sprinkler Corrosion, FAQs for Wet Pipe Nitrogen Inerting (WPNI), FAQs for Dry Pipe Nitrogen Inerting (DPNI), Installation Schematics, Case Studies, etc.

    (submitted by K. Mniszewski)