Corrosion is a more serious problem than many cooling tower operators realize. If left unchecked, corrosion can reduce the cooling tower’s efficiency, damage critical components, and shorten the lifespan of your entire system. It also weakens the structure of your cooling tower, leading to leaks and breakdowns and even compromising the safety of your crew.
At Pinnacle CTS, we advise customers to include corrosion control in preventive maintenance. This step is as critical as cleaning the cooling tower and calibrating equipment.
In this post, we will share a few ways to identify and keep cooling tower corrosion in check.
But first, let’s understand why cooling towers are prone to corrosion.
Why Cooling Towers Are Prone to Corrosion
Corrosion is a chemical reaction that starts when a material, especially metal, reacts with the surrounding environment. This reaction leads to rust and material breakdown.
When it comes to cooling systems, corrosion starts when water, air, and metal components interact. If ignored, cooling tower corrosion can lead to leaks, structural damage, and equipment failure.
Cooling towers are susceptible to different types of corrosion, including:
- Galvanic corrosion occurs when two different metals come into contact with water, causing one metal to degrade faster than the other.
- Pitting corrosion occurs when small, localized spots of metal are corroded. It leaves behind deep pits, which may eventually lead to leaks.
- Microbiologically influenced corrosion (MIC) results from bacteria and microorganisms growing in the water. They often create acidic by-products that speed up corrosion.
Several factors contribute to cooling tower corrosion, including:
- Water chemistry, or the lack of it, leads to poorly balanced pH levels or high levels of chlorides and sulfates, which can accelerate corrosion.
- Environmental conditions like temperature and humidity can also contribute to corrosion.
- Materials used in your cooling tower can affect how quickly corrosion happens. Metals, especially those made of steel, are particularly vulnerable.
Focus On Systematic Water Treatment
Water treatment is at the heart of corrosion control in cooling towers. If you fail to monitor water chemistry, it can put corrosion on the fast track. Maintaining the right water chemistry includes testing and treating the water using suitable chemicals.
1. Balance the pH
The first step is keeping the pH levels, alkalinity, and hardness within the recommended range. If the water is too acidic or alkaline, it can lead to corrosion. Likewise, hard water can put a wrench in your corrosion control. It is recommended to maintain the pH level between 6.5 and 7.5 to help minimize cooling tower corrosion.
2. Use Corrosion Inhibitors
Next, you should add corrosion inhibitors to the water to protect metal surfaces. These chemicals form a protective film on the metal, preventing it from reacting with water and oxygen. Chromate and molybdate are the most reliable corrosion inhibitors. You should choose the one that’s compatible with your cooling tower.
3. Monitor and Adjust
Monitor and adjust water treatment chemicals regularly. Frequently testing the water helps you maintain the desired pH levels and keep cooling tower corrosion under control. You can hire a professional for this preventive maintenance and ensure your system runs at its peak.
Choose Corrosion-Resistant Materials
Using corrosion-resistant materials is another effective way to prevent cooling tower corrosion. When building or upgrading a cooling tower, pick corrosion-resistant materials, which can lower maintenance and repair costs in the long run.
While stainless steel is a good choice, you can find several better alternatives, such as High-Density Polyethylene (HDPE). Unlike stainless steel and other metals, this thermoplastic offers excellent resistance to chemical corrosion and handles UV radiation. It’s also lightweight and can be molded into a seamless shell that doesn’t leak.
Fiberglass is another great option because it’s lightweight, durable, and immune to rust. If you don’t want to replace stainless steel, you can still use other materials for parts, like piping and fill media. As they are not susceptible to corrosion like metal parts, you can save on repairs and replacements in the long run.
Don’t Ignore Cathodic Protection
Cathodic protection is a highly effective corrosion control process. This technique uses the principle of turning active parts of a metal surface into passive or cathode. Essentially, cathodic protection neutralizes the electrochemical reactions that cause corrosion.
Cooling tower corrosion prevention relies on two types of cathodic protections:
1. Sacrificial Anodes
It is the simplest corrosion control method, where sacrificial anodes protect the cooling tower’s metal surface. Once the sacrificial anode corrodes completely, it gets replaced to continue the protection. Zinc, magnesium, and aluminum are the most commonly used sacrificial anodes, but some systems also use polyphosphate, polysilicate, and phosphonates.
2. Impressed Current Systems
Impressed current systems use an external power source to apply a small electrical current to the cooling tower, preventing corrosion. They use different materials as anodes, such as graphite rods, silicon-iron alloys, and lead-silver alloys. However, this corrosion control measure is not as cost-effective as sacrificial anodes.
Schedule Regular Inspections and Maintenance
Effective corrosion control rests on regular inspection and maintenance. Without regular upkeep, a small patch of rust can spread across the cooling tower, damaging its structure. All cooling tower manufacturers and service experts recommend creating a preventive maintenance plan and sticking to it.
1. Regular Inspections
Regular inspections are the first step in effective cooling tower maintenance. These inspections should focus on checking for signs of corrosion, such as rust, scaling, or leaks. Catching corrosion early allows for faster, more affordable repairs.
2. Cleaning and Descaling
Cleaning and descaling are also critical maintenance tasks. Scaling occurs when minerals in the water accumulate on the cooling tower’s surfaces, which affects heat transfer efficiency and increases the risk of corrosion. However, routine cleaning and descaling can prevent these mineral deposits from becoming a problem.
3. Replacements and Upgrades
Corroded components weaken the system and must be repaired or replaced immediately to prevent further damage. Regularly monitoring water quality can help check if your chemical treatments are working.
Talk to Our Cooling Tower Corrosion Prevention Experts
Your cooling tower can last longer with effective corrosion control, which involves regular water treatment and monitoring, using corrosion-resistant materials, implementing cathodic protection, and maintaining a consistent inspection schedule. Concerned about managing corrosion prevention? You can hire a team of professionals to handle the maintenance for you.
That’s where we come in. Pinnacle CTS specializes in all things cooling towers. We can help you with selection, installation, maintenance, and repairs. We serve the greater tri-state area and provide 24/7 emergency service.
Contact us today to schedule your consultation.
