Corrosion is one of the most common and costly issues affecting fire pump systems worldwide. Whether you operate electric fire pumps, diesel fire pumps, or vertical turbine fire pumps, corrosion can gradually weaken components, reduce system performance, and even cause pump failure in critical emergencies. For industries where fire protection cannot fail, preventing corrosion is not just maintenance—it is a core part of risk management.
For facility managers, fire protection designers, and contractors, understanding why corrosion develops and how to prevent it is essential. This article explains what causes corrosion in fire pumps, how to identify early warning signs, and practical steps to protect your fire pump system and extend its service life.
Corrosion in fire pumps occurs when metal components react with water, oxygen, chemicals, or environmental contaminants. Different pump types face different corrosion risks. Vertical turbine pumps may suffer corrosion from groundwater minerals, while diesel fire pump systems experience humidity-induced corrosion due to engine heat.
Common causes include:
High mineral content, such as calcium, magnesium, or iron
Chlorides, especially in coastal areas, which aggressively attack metal surfaces
Dissolved oxygen that accelerates oxidation
Contaminants from industrial water sources
Poor water quality is one of the biggest triggers for internal corrosion of pump casings, impellers, and piping.
Fire pump rooms often have:
High humidity from water leakage or condensation
Poor ventilation
Significant temperature fluctuations
These conditions create ideal environments for external rust formation, especially on cast iron or steel components.
MIC is caused by bacteria that create acidic byproducts inside piping or tanks. These microorganisms thrive in stagnant water, making fire protection systems—especially those rarely activated—vulnerable to this type of corrosion.
Fire pumps located near chemical storage, industrial process areas, or wastewater treatment zones face additional corrosion risks. Chemical vapors or airborne salts can settle on pump surfaces and initiate corrosion.
Corrosion often accelerates when:
Pumps run infrequently
Routine inspections are skipped
Drain lines are blocked
Leaks are left unrepaired
Protective coatings are not renewed
The longer corrosion continues unnoticed, the more severe the damage becomes.
Ignoring corrosion can cause:
Corroded impellers and casings create rough internal surfaces, disrupting water flow. This results in:
Lower pump discharge pressure
Reduced flow rate
Higher power consumption
Over time, efficiency losses can cause the pump to operate outside NFPA 20 requirements.
Corrosion weakens critical components such as:
Shaft sleeves
Bearings
Couplings
Impellers
Casing bolts
A weakened pump is more likely to fail during an emergency.
Corroded pumps require more frequent component replacement. Severe cases may require complete pump replacement far earlier than expected.
Fire pumps must function instantly and reliably during emergencies. Corrosion that reduces system reliability can lead to:
Insurance compliance issues
Failed fire inspections
Increased liability for facility owners
In the fire safety industry, reliability is everything—corrosion undermines that reliability.
Effective corrosion protection requires a combination of proper materials, environment control, water quality management, and routine maintenance. The following strategies are used by top fire pump manufacturers and fire protection engineers worldwide.
The first step in corrosion protection begins during pump selection.
For environments with high corrosion exposure, consider pumps made with:
Stainless steel impellers
Bronze or brass components
Epoxy-coated cast iron
Duplex stainless steel for severe marine or industrial conditions
These materials resist water aggression and significantly slow corrosion development.
Manufacturers offer corrosion-resistant coatings such as:
Fusion-bonded epoxy
Polyurethane coatings
Powder coatings
Internal coatings protect the pump casing and impeller from direct water contact, helping maintain long-term performance.
Fire pump rooms should follow environmental standards to reduce corrosion risk.
Good airflow prevents condensation. Use:
Mechanical ventilation
Exhaust fans for diesel pump rooms
Air-drying systems in humid regions
Maintaining stable temperature reduces condensation on pump surfaces.
Aim for:
Temperature above freezing
Humidity < 60% when possible
Avoid exposing pump components to sudden temperature changes.
Standing water around pumps contributes to corrosion. Make sure:
Floors slope toward drainage
Leaks from valves and pipes are repaired immediately
Pump room is kept dry and clean
A dry environment is a corrosion-free environment.
Water quality is critical, especially for long-term internal protection.
Water should be tested for:
Chloride concentration
pH levels
Hardness
Total dissolved solids (TDS)
High chlorides and high hardness accelerate metal corrosion.
If water quality is poor, consider:
Filtration
Softening systems
Corrosion inhibitors (compatible with fire protection systems)
Vertical turbine fire pumps may require special treatment if groundwater contains corrosive minerals.
Flushing removes sediments and bacteria that contribute to corrosion.
A routine flushing schedule helps maintain clean internal surfaces.
Protective coatings provide a barrier between pump metal and corrosive elements.
Epoxy-based coatings are widely used because they:
Resist chemicals
Withstand high pressure
Bond well to cast iron surfaces
They are ideal for pump volutes and impellers.
External anti-corrosion paint protects the pump from humidity, salt, and environmental contaminants.
In certain severe environments, such as marine applications, cathodic protection systems can be installed to prevent electrochemical corrosion.
No corrosion-prevention strategy is complete without regular maintenance. NFPA 20 recommends routine operation and inspection to prevent degradation.
Running the fire pump weekly allows:
Water circulation
Reduced stagnation (which causes MIC)
Early detection of unusual vibration or noise
Weekly churn tests also distribute lubricants and prevent rust buildup.
Check for:
Rust on pump exterior
Leaking seals or gaskets
Flaking paint
Moisture accumulation
Shaft alignment
Bearing conditions
Early detection prevents large repair costs.
Annual maintenance should include:
Full inspection of pump casing
Internal component check
Recoating if necessary
Replacement of corroded parts
Testing relief valves and pressure controllers
A well-maintained fire pump can last decades with minimal corrosion damage.
Fire pumps cannot be fully protected if the associated piping is corroding.
Options include:
Galvanized steel
Copper (for smaller lines)
Stainless steel
Internally coated steel pipe
Stagnant water is the number one cause of MIC.
Use:
Regular flow tests
Proper system drainage
Balanced water circulation
Pressure fluctuations can draw in air, which introduces oxygen into the water and increases corrosion risk.
Diesel fire pumps face unique corrosion challenges due to heat and exhaust byproducts.
Corrosion often forms near exhaust piping. Ensure:
Heat insulation
Leakage-free joints
Proper ventilation
Diesel engines produce heat that increases humidity, leading to rust on pump bases and controllers.
Lubrication prevents oxidation on metal surfaces such as linkages and couplings.
Facility managers should watch for:
Rust stains on casing
Changes in pump vibration
Drop in discharge pressure
Brownish or cloudy water during churn tests
Visible pitting on metal surfaces
Peeling coatings
Misalignment due to corroded mounting bases
Any of these signs warrant immediate correction.
Corrosion may not be immediately visible, but it is one of the most silent and destructive threats to fire pump systems. By selecting corrosion-resistant materials, maintaining environmental control, improving water quality, using protective coatings, and performing regular maintenance, you can significantly extend the life of your fire pump and ensure maximum reliability when it matters most.
A properly protected fire pump not only reduces long-term operational costs but also ensures that your fire protection system remains ready for emergencies at all times. In fire safety, prevention is always better than replacement—and corrosion prevention is a critical part of that strategy.
