All fire sprinkler systems corrode. That is an unfortunate truth that many building owners may overlook until leaks begin to develop in their facilities. In many facilities, it is rare that a building owner will be proactive regarding a corroding fire sprinkler system until damage has occurred and leaks have begun to develop.
The first several leaks are often just repaired, but once they become enough of a nuisance or expense the owner will look to their fire sprinkler contractor for a solution to the problem. More often than not, the contractor will recommend complete system replacement. However, this does not take into consideration the highly localized nature of corrosion in fire sprinkler systems and results in the significant expense of replacing pipe, much of which may still be in excellent condition.
Surgical replacement of the most damaged piping, followed by the implementation of a corrosion control strategy, is often a much more cost-effective approach to stopping future leaks.
The primary type of corrosion in water-based fire sprinkler systems is oxygen corrosion. Oxygen corrosion requires three components to occur: an electrolyte (liquid water), oxygen, and metal in contact with the water (most often iron and zinc in this industry).
These three elements are only abundantly present in certain locations in a given type of system, with the remainder of the system piping experiencing only minor corrosion rates.
Here are some characteristics of corrosion in wet and dry pipe systems:
Wet Pipe Systems
- Trapped air contains the vast majority of the oxygen available to cause corrosion.
- The most severe corrosion is isolated to where the trapped air is located (the system high points).
- Piping that remains water-filled (no trapped air) does not experience significant corrosion.
Dry and Preaction Systems
- The location of trapped water is the limiting component regarding corrosion, with severe corrosion occurring anywhere trapped water is present (the system low points).
- Oxygen is over-abundant, assuming the supervisory pressure is maintained with compressed air.
- Piping that is completely dry will not corrode.
Keeping the corrosion characteristics of each type system in mind, we can begin to determine what pipe has experienced the most severe corrosion (and may need to be replaced) with a walk-through of the facility and by identifying where leaks have previously occurred. In mission-critical environments, where leaks cannot be tolerated, it's often necessary to gather hard data on the condition of the system piping before making a decision on a path forward.
ECS offers two primary investigative tools to gather this data:
ECS Corrosion Risk Assessment
In a Corrosion Assessment, an ECS Engineer, along with a local fire sprinkler contractor, performs an on-site internal investigation to determine the location and severity of corrosion throughout the system piping. The assessment includes:
- Video scoping footage of the internal conditions of the system piping, along with a comprehensive report detailing all the on-site findings and observations, is provided to the client.
- Additional analytical testing may be performed to quantify the severity of the corrosion that has occurred.
ECS Pipe Sample AnalysisOur pipe analysis provides quantified data on the amount of metal loss that has occurred when video scoping is not needed.
- A local fire sprinkler contractor takes pipe samples from those locations expected to have experienced the most severe corrosion, including:
- High points on wet systems where air is trapped.
- Low points on dry and preaction systems where water is trapped.
- After receiving the sample, we compare pipe wall loss to current industry standards. This provides us with crucial information on whether pipe replacement is necessary.
With hard data on the severity of metal loss that has occurred in a given system, the building owner is equipped to make informed decisions on what the most cost-effective approach is to mitigate the damage that has occurred.
Regardless of how much pipe is replaced, if any, ECS always recommends the implementation of a nitrogen-based corrosion control strategy to prevent further oxygen corrosion damage from taking place. By removing oxygen from the system before it can cause corrosion, and preventing its re-entry, the service life of an existing system can be significantly extended.
Our team of experts is always available to help you devise and implement a corrosion control strategy. Contact us today.