New Cooling System Coming Online: How Can I Minimize Corrosion and Protect My Plant?

We were recently called to assist an engineering company working nationally that were suffering significant corrosion issues with a newly installed evaporative condenser. Despite being in service for only a few months, the system showed severe corrosion due to inadequate passivation and poor chemical dosing control.

Startup is the most critical phase for a new cooling water treatment program. If metal surfaces are left unpassivated or insufficiently passivated, they will corrode rapidly when exposed to water for the first time. The resulting corrosion products typically form loose, porous deposits that impair heat transfer and hinder the effectiveness of future corrosion inhibitors.

To prevent this, new cooling systems must be properly prepared for passivation. This involves removing mill scale, oil, grease, and other debris left from manufacturing to expose clean metal surfaces ready for treatment. The selection of cleaning agents—such as chelants and dispersants—must be carefully chosen based on the system's specific metallurgy.

Once the system is cleaned, the exposed metal is highly vulnerable to flash corrosion, so it’s essential to quickly initiate passivation. Passivation is a chemical process that forms a protective oxide layer on the metal surfaces, reducing their susceptibility to corrosion. This is achieved by introducing passivating chemicals into the cooling water.

After the passivation process is complete, a high dose of the chosen corrosion inhibitor should be applied to establish a protective film on the metal surfaces. This helps create a durable passivation layer on top of the initial oxide layer that can then be maintained with regular dosing.

Additionally, Legionella control is a key concern. Before operating your system, ensure you are registered as a cooling tower operator with the local council. You must also conduct a Legionella risk assessment and develop a comprehensive chemical treatment and monitoring plan. Disinfection of the system is required before it can be brought online.

Finally, to maintain the integrity of the passivation layer throughout the system’s life, careful monitoring of water quality is essential. Fluctuations in pH, overdosing of halogens, and underdosing of inhibitors can damage the underlying oxide layer, leading to corrosion. Continuous care is necessary to both create and protect this crucial layer over time.

If you are planning to put a new cooling system into service why not get in touch with Hydrology and we can advise you on the correct start up process to help you avoid a costly mistake and protect your assets into the future.