Corrosion is a major issue for all sprinkler systems. Corrosion damage can restrict water flow to sprinklers and impair mechanical operation, rendering a system inoperable over time. However, corrosion in sprinkler systems is preventable and treatable with regular sprinkler system inspections and maintenance.

sprinkler system corrosion

How does corrosion occur in a sprinkler system?

Corrosion is the spontaneous electrochemical oxidation, ionization, and dissolution of metals into contacting water. When metals are exposed to electrolytes (water with ions in it), corrosion spontaneously occurs.

There are several ways sprinkler system piping can become corroded, and a variety of factors that come into play. These factors include the type of metal piping used, the environment, and the design of the sprinkler system.

Sprinkler systems can experience two types of corrosion:
• Generalized corrosion (rust) occurs when oxygenated air enters the interior metal piping of a sprinkler system.
• Microbiologically Influenced Corrosion (MIC) occurs in the presence of bacteria (Acid Producing Bacteria (APB), Sulfur Reducing Bacteria (SRB), or Iron Related Bacteria (IRB)).

Generalized corrosion is more common than MIC, causing 60 percent of all cases versus 40 percent influenced by MIC.

Dry System vs. Wet System Corrosion

Because all sprinkler systems have the necessary components for corrosion to occur (water, oxygen, and metal), all system types can experience generalized and MIC corrosion, just in different ways.

1. Wet system corrosion is typically caused by:
• Air pockets created during construction of the system

2. Dry system corrosion is typically caused by:
• Condensation from moist, trapped air
• Trapped air after system flow testing

In all systems, this presence of trapped air creates an environment more conducive to bacteria that can lead to MIC corrosion.

In fact, recent data suggests that “the ideal systems for MIC damage are those in which the water is seldom supplemented and does not circulate; ones with lots of dead end pipes; and those that are at ambient temperatures.” This means that basically any sprinkler system is at risk for MIC in addition to generalized corrosion.

Common Types of Corrosion Failures

There are several types of corrosion failures that can occur as a result of corrosion. The most common corrosive failures include:

1. Pitting
• The most common form of corrosion for dry systems
• Can lead to through-wall perforations and leaks

2. Build-up of corrosion products and scale
• Build up leads to loss of system flow

3. General wall loss due to ionization of iron atoms
• Leads to loss in the structural integrity resulting in the breakdown of the pipe system

Signs of Corrosion

Call your fire protection company at the first sign of corrosion. There are ways to remedy the problem if caught early. Depending on the type of corrosion, some signs may include:

• Pin hole leaks
• Black/smelly water in sprinkler system
• Water stains concrete with rust during flow tests
• No water comes out during testing

How to Prevent Corrosion of Sprinkler Systems

A fire sprinkler system is an asset to a building and the people in that building. Taking steps to prevent corrosion will assist in the longevity of a fire sprinkler system.

Routine maintenance and regular inspections of a sprinkler system are the best way to prevent corrosion of any kind, for all systems.
If a sprinkler system is prone to corrosion, your fire protection company may suggest preventative measures to help mitigate corrosion. These may include:

• Nitrogen generators that apply nitrogen gas as needed to eliminate the presence of oxygen (an element required for corrosion)
• Dynamic biohazard inhibitors that can prevent MIC
• Additives that are designed to coat the interior of the piping to resist or deplete corrosion

A fully functioning fire sprinkler system is a vital component to an effective fire protection strategy. These dynamic systems are often complex and require regular inspections and maintenance.

Performing regular sprinkler inspections with Fire Systems can help you to detect any signs of corrosion at an early stage. We inspect your sprinkler system using Fire Systems, Inc. technicians – with no sub-contracting.

Financing Repairs or Replacement of Your Sprinkler System(s)

Small and medium sized business owners are now able to write off expenses related to fire protection and alarm systems thanks to changes in Section 179 passed in December 2017.

Businesses are now allowed to claim up to $1 million in tax deductions compared to $500,000 in the previous year. The new law also increases the bonus depreciation percentage from 50 percent to 100 percent for any purchases made between September 27, 2017 to December 31, 2022. Depreciation can also be applied towards used equipment purchases.

Call 770-333-7979 to schedule a FREE consultation or visit our website to learn more.