How Oxygen Scavenging Chemicals Prevent Boiler Corrosion

Boiler systems depend on precise water chemistry to stay safe, efficient, and operational. One of the most serious threats to system health is corrosion, largely driven by dissolved oxygen. Even trace amounts of oxygen can create long-term damage – weakening metal surfaces and triggering expensive failures.

To prevent this, facility managers and water treatment professionals rely on a critical tool: oxygen scavenging chemicals.

What Are Oxygen Scavenging Chemicals?

Oxygen scavengers are chemical agents designed to eliminate dissolved oxygen from boiler feed water and condensate systems. Once added to the water, these oxygen scavenger compounds react with oxygen molecules, forming stable byproducts and removing the root cause of corrosion before the water enters the boiler.

These oxygen scavenger chemicals are a key component of any water treatment program – especially in steam boilers operating at high temperature and pressure. Without them, even well-designed systems will suffer from internal pitting, leaks, or tube failure over time.

Why Is Dissolved Oxygen So Problematic?

Dissolved oxygen in feedwater leads to rapid metal oxidation inside the boiler. The reaction between oxygen and iron generates rust, weakens pipes and tanks, and contributes to sludge formation. In high pressure boilers, these reactions are even more aggressive due to elevated temperatures.

Consequences include:

• Accelerated corrosion of tubes and drums
• Reduced heat transfer efficiency
• Compromised system reliability
• Costly unplanned shutdowns

Even when using deaeration systems, trace oxygen often remains in the water. That’s why chemical treatment is essential to eliminate what mechanical systems can’t.

Types of Oxygen Scavengers

Oxygen scavenging chemicals come in two main forms:

• Inorganic oxygen scavengers – fast-acting, typically based on sodium sulfite; economical but increase total dissolved solids (TDS) and may require blowdown management
• Organic oxygen scavengers – such as DEHA or carbohydrazide; ideal for high-temperature systems, do not increase dissolved solids, with lower toxicity and minimal residue

The type you choose should match your boiler system’s pressure, feed water temperature, and treatment goals.

Dosing and Temperature Considerations

Oxygen scavenger performance is temperature dependent. At lower temperatures, chemicals react more slowly with oxygen. For that reason, low-pressure systems may need longer contact time or a different chemical formulation. At higher temperatures, especially in power and industrial applications, fast-reacting formulas and proper catalyst selection are critical.

Overdosing of oxygen scavengers increases cost and can elevate TDS; underdosing leaves metal surfaces exposed. That’s why careful dose control matters.

Monitoring and System Control

Using oxygen scavengers effectively means knowing your system’s chemistry in real time. STPs should:

• Monitor dissolved oxygen levels continuously or through regular lab sampling
• Track feedwater and condensate pH, as well as feedwater temperature
• Adjust dosing rates based on temperature and system load
• Maintain chemical logs for compliance and trend analysis

Automated feed systems can help maintain the right dose rate, especially in systems with fluctuating steam demand.

Part of a Complete Treatment Program

Oxygen scavengers, when inorganic oxygen scavengers or organic oxygen scavengers, work best when integrated with:

• External treatment like reverse osmosis or filtration
• pH and alkalinity adjustment with sodium hydroxide
• Internal conditioning with sodium phosphate or polymer blends

Together, these form a comprehensive defense against scale, corrosion, and boiler system failure.

Visit our Boiler Water Treatment page to explore Clearwater’s full-service programs.

Don’t Let Oxygen Ruin Your System

Corrosion doesn’t happen overnight – but once it starts, it’s costly to reverse. Oxygen scavenger chemicals are your best defense against long-term degradation, equipment failure, and unexpected downtime.

These chemicals don’t just prevent corrosion – they help extend the overall service life of your boiler system.

Need a smarter treatment plan? Contact Clearwater to evaluate your boiler’s water chemistry and start protecting your system from the inside out.