BUILDINGS - Smarter Facilities Management

08/29/2016

Safety Corroded: Why Your Fire Sprinkler System May Be At Risk

Understand and address the issues that undermine your fire safety system

By Justin Feit

 
  • /Portals/0/images/Magazines/2016/0916/Article_Images/B_0916_FireSprinkler_SprinklerVent.jpg

    NFPA 13 (2016) is the most recent version of fire sprinkler standards. Included are new standards to include air vents in wet-pipe systems like the one pictured. These new standards require the installation of a single air vent near a high point in systems using metallic pipes. The vent allows air to be removed from that portion of the system to reduce corrosion (7.1.5 & 8.16.6). PHOTO COURTESY OF ENGINEERED CORROSION SOLUTIONS

  • /Portals/0/images/Magazines/2016/0916/Article_Images/B_0916_FireSprinkler_N2-Blast-Install-2.jpg

    Nitrogen systems fill piping in dry-pipe and preaction sprinkler systems with inert nitrogen. This forces oxygen out of the pipes, thereby preventing corrosion. PHOTO COURTESY OF SOUTH-TEK SYSTEMS, LLC

The fire department of Hays, KS rushed to a hotel in June to find that it was not only facing a damaging fire, but also a flow of water that threatened to collapse the building. The cause of that threat – a malfunctioning sprinkler system.

The fire department could not effectively take on the fire through conventional methods, but it was able to evacuate the building safely and eventually extinguish the fire. However, this took nearly seven hours, and the hotel sustained considerable damage.

Typically, sprinkler systems are incredibly effective at reducing the impact of fires. The National Fire Protection Agency (NFPA) found that 96% of sprinkler systems worked in suppressing fires when they operated properly.

Sprinkler systems provide an important sense of security because of the safety they offer to buildings and their inhabitants. Yet, as with the incident in Hays, this is only possible when the systems are working properly. If not, they can allow and contribute to catastrophic damage.

Most sprinkler issues – like in Hays – can be avoided through locating and treating the problem in the sprinkler system. But even though you might inspect your own sprinkler system often, some major problems are just not visible. Damage from the inside of the pipes may be the source of the problem, and those are difficult – or even impossible – to detect on your own.

To maintain your sprinkler system’s efficacy, the NFPA – whose standards are often adapted into laws – requires inspections of the internal piping every five years. In temporarily shutting down the system, this inspection checks the piping for obstructions.

However, this standard may not adequately address the threat of corrosion, which works quickly and undermines the safety of fire sprinkler systems.

Finding the Causes of Corrosion

Because so many fire sprinkler systems are composed of metal pipes, water and compressed air, corrosion is always a risk and can begin quickly. “Corrosion processes can happen almost instantaneously – within seconds of flooding the pipe,” says Dr. Jeff Pfaendtner, Principal Engineer at Veracis Engineering in Minneapolis. Corrosion can damage internal piping quickly if conditions are not right.

Pfaendtner notes, “People might think that water is just water, regardless of the source. But it’s not.” Even water treated by municipalities can be suspect and cause corrosion simply because of the way it may be treated.

“To treat water and make it taste better, municipalities may bubble oxygen through the water to settle out iron. But you may end up with an excess of dissolved oxygen in the water,” says Pfaendtner. In wet-pipe systems, the dissolved oxygen often causes some of the more insidious problems because it goes unnoticed.

And oxygen should not be overlooked in sprinkler pipes. Corrosion in piping is generally rust accumulation from the presence of three simple substances: iron, water and oxygen. The removal of just one of these three will stop most kinds of corrosion, but that can be difficult in a sprinkler system where water and iron are often two of the main materials inherent in systems. Oxygen also finds its way into preaction and dry systems because they are designed to be filled with air.

“If you have a significant amount of oxygen and water coexisting inside your steel pipes, you can have corrosion and pitting all the way through the pipe wall in less than five years,” says Jeff Harrington, President and CEO at Harrington Group, Inc. in Duluth, GA. Harrington has even seen cases that have developed within two to three years of installation.

This means that the code requirement of checking piping interiors every five years may not be enough. However, there are actions you can take to prevent corrosion issues in your sprinkler systems.


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