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Passivation is a technique used to make a metal passive. It reduces the corrosive effects of environmental factors, such as water or air, through the formation of a protective film on the surface of the metal.

In essence, it shields the base material and helps the surface to become resistant to corrosion.

Preserving the art of passivation is important.

Over time metals can suffer significant deterioration if not passivated. This may cause system failures, lead to higher repair costs and more frequent production shutdowns. It may also cause harm to people and the environment.

Despite the importance of passivation, the process is often overlooked during the commissioning phase. This is because there are perception issues surrounding the benefits of passivation.

This is due to the difficulty in confirming the efficacy of the process, but also because non or poor passivation will often have no immediate effect.

Hydrochem marketing lead, Neil Cox, said problems can take years to manifest, but when they do the failures are catastrophic.

“The difficulty in demonstrating immediate value to the client reinforces a perception the process therefore should not cost much,” he said.

“Circuit volumes are necessary to accurately calculate the dose for each treatment chemical required, yet these are often not provided. This can have a direct effect on both the cost and the overall outcome.”

Selecting the correct treatment is of paramount importance but can be destabilised by the presence of unexpected non-traditional metals, poor make up water quality or other unanticipated operating conditions. 

“Passivation can be impacted by a reticence to drain the system between processes for environmental reasons,” Cox said.

“This can viewed as shortsighted when considering the potentially curtailed life expectancy and enduring sub-par performance of non-passivated systems.”

Unfortunately, the passivation process is typically one of the last tasks in the commissioning schedule. The inevitable concertina of activity as handover looms can lead to insufficient time being allowed to properly complete the recommended passivating activities.     

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