Heat Exchangers Cleaning with the Right Water Treatment Chemistry

Heat exchanger cleaning is one of the most important maintenance practices in industrial water systems. Over time, scale formation and fouling can accumulate on the surfaces of heat exchangers, blocking flow paths and reducing heat transfer efficiency. Even a thin layer of deposits acts as insulation, forcing equipment to work harder and driving up energy use. Without proper care, scaling can shorten equipment life, increase operational costs, and lead to unexpected downtime. By applying the right water treatment chemistry, facilities can achieve efficient cleaning, protect critical components, and keep heat exchangers performing at their designed capacity.

Why Heat Exchangers Need Regular Cleaning

Heat exchangers are built to move heat efficiently between hot and cool fluids, but their performance declines quickly when scale and debris build up inside. In tube heat exchangers and shell-and-tube units, deposits cling to the internal surfaces, narrowing flow paths and disrupting fluid circulation. This buildup restricts flow rate, reduces heat transfer, and raises system pressure, which can strain pumps and other connected components.

The consequences extend beyond reduced performance. As scale thickens, the exchanger must run hotter to maintain output, raising energy demands and accelerating equipment wear. Corrosion often follows when untreated deposits trap moisture against metal surfaces. Left unchecked, fouling leads to costly repairs, frequent maintenance, and increased operational costs. Regular cleaning ensures tubes remain clear, surfaces transfer heat as designed, and the overall system runs safely and efficiently.

Common Types of Scale and Deposits

Not all fouling is the same, but most heat exchanger problems stem from mineral-based deposits. The most common is calcium carbonate, which forms when dissolved calcium and carbonate ions exceed their solubility and fall out of suspension. This type of scale hardens into tough deposits that line exchanger tubes and restrict heat transfer.

Other common forms of scale and debris include:

• Magnesium deposits – contribute to hardness scale and reduce heat transfer efficiency.
• Silica scale – forms stubborn layers that are difficult to remove with standard cleaning methods.
• Rust and lime – settle in tight spaces within shells and tubes, accelerating wear and pressure drops.
• Mixed deposits – combinations of minerals and particulates that create uneven, layered buildup.

These fouling materials lead to reduced flow, higher system pressure, and eventual equipment wear. Over time, they cause costly repairs and more frequent maintenance cycles. Understanding the composition of scale is the first step in selecting the right chemical solution for effective removal.

Chemical Solutions for Effective Heat Exchanger Cleaning

Removing scale deposits from heat exchangers requires more than just mechanical brushing or flushing. Chemical solutions are essential for dissolving mineral buildup and dispersing loosened debris so it does not resettle. The choice of chemistry depends on the exchanger’s construction materials, the type of deposits, and the severity of fouling.

For heavy deposits, hydrochloric acid is often used because it reacts quickly with calcium carbonate and other mineral layers. However, hydrochloric acid must be carefully applied with inhibitors to protect sensitive metals and prevent corrosion. In cases where equipment contains stainless steel or other delicate materials, citric acid or blended organic acids may be chosen. These alternatives deliver efficient cleaning without the aggressive attack of stronger acids.

Additional additives, such as dispersants, foam control agents, and corrosion inhibitors, are used to keep tubes and surfaces safe during the cleaning process. By selecting the correct acid base and protective chemistry, operators can prevent accidents, reduce cleaning time, and achieve a highly effective restoration of heat transfer efficiency.

Step-by-Step Cleaning Process to Avoid Costly Repairs

Heat exchanger cleaning must follow a structured procedure to ensure safety and reliable results. While each facility may adjust the details based on system design, the following general cleaning process highlights best practices:

1. Isolate the unit – Shut valves and remove the exchanger from active service to avoid cross-contamination and pressure hazards.
2. Prepare the cleaning solution – Mix the appropriate acid blend and inhibitors in a dedicated tank, ensuring compatibility with the exchanger’s materials.
3. Set up circulation equipment – Connect a pump to circulate the solution through the tubes and shell for even contact across all surfaces.
4. Monitor conditions – Track pH, pressure, and temperature during circulation to confirm the solution is actively dissolving deposits.
5. Neutralize and flush – Once deposits are removed, neutralize the acid and flush with fresh water to return surfaces to safe operating conditions.
6. Final inspection – Check for remaining debris, inspect components for wear or corrosion, and repeat the process if necessary.

This method ensures deposits are dissolved rather than displaced, leaving the exchanger clean, passivated, and ready to return to service.

Preventive Strategies: Early Detection and Water Treatment

While chemical cleaning restores performance, prevention is the best strategy to protect heat exchangers over the long term. Operators can spot potential fouling through early detection methods, such as monitoring flow rate, ΔT (temperature difference), and system pressure. A decline in these indicators often signals scale buildup before it becomes severe.

Beyond monitoring, pretreatment plays a critical role in protecting exchanger systems. Technologies such as water softening, reverse osmosis, and threshold inhibitors reduce mineral content, slowing scale formation and corrosion risk. When paired with regular water analysis, these methods help facilities maintain efficiency and extend equipment life.

Training staff to recognize early warning signs, documenting operating conditions, and scheduling proactive maintenance are equally important. With the right preventive methods, operators can avoid costly downtime and keep exchangers running at peak performance.

ETI’s Role in Heat Exchanger Cleaning

At ETI, we understand that no two water systems are exactly alike, which is why our solutions focus on chemistry tailored to your needs. Our expertise in custom blending ensures that each cleaning solution works effectively on the specific deposits, materials, and operating conditions of your system. Whether dealing with stainless steel, copper, or mixed metals, ETI formulations are designed to protect components while dissolving even the toughest deposits.

We also equip water treatment professionals with the knowledge to perform safe, efficient cleanings. Through our ETI Bootcamp and preparation programs, operators learn to recognize early warning signs of fouling, select the right chemical blends, and apply the proper cleaning methods to restore efficiency.

ETI’s Water Scale Remover line is specifically engineered to dissolve calcium carbonate, lime, and rust deposits in boilers, cooling towers, and heat exchangers. These blends not only eliminate existing scale but also condition surfaces to resist future buildup, helping facilities reduce maintenance costs, extend system life, and avoid costly downtime.

Ready to improve your system’s performance? Contact ETI today to discuss the best treatment program for your facility and keep your heat exchangers operating at peak efficiency.