Corrosion protection is an integral part of the layup/startup checklist that is too often overlooked—sometimes solely due to lack of information, says Cortec Corporation, a corrosion specialist.
Simple corrosion prevention strategies not only minimise complications such as clogging and high iron levels at startup but also offer long-term benefits by discouraging the onset of leaks and promoting a longer asset service life overall.
The following tips offer helpful insights into how water treatment service providers and boiler/cooling water system operators around the globe can make their lives easier and their assets last longer.
Northern hemisphere: best practices for cooling system layup and boiler startup
For many, cooling tower winterisation or chiller layup mean little more than shutting down the system and hoping for the best. However, without standard water treatment chemistry circulating through the system, the metal surfaces are vulnerable to corrosion that will gradually eat away at the asset, thinning the walls and releasing corrosion products into the water year after year.
Adding a simple treatment such as the Cortec Cooling Loop Gator prepares the system for wet or dry layup. Circulating these film-forming corrosion inhibitors through the system for 12-24 hours leaves behind a protective layer that offers protection above and below the water level (as long as the system remains closed) and does not need to be removed at startup.
Boilers are often brought back online at the same time cooling water systems are shut down, when the need for residential and commercial cooling gives way to heating demands.
Boilers are especially vulnerable to corrosion as fresh, unheated, highly oxygenated water floods the system before the normal operating water treatment chemistry programme is in place. Pitting corrosion is common and can easily be counteracted by adding a Boiler Egg to the boiler before startup. This water-soluble pouch dissolves in the makeup water, releasing active chemistry that scavenges oxygen and passivates metal surfaces in the critical startup phase. It also has NSF G7 certification for use in food processing areas where the treated water or steam has no food contact.
Southern hemisphere: boiler layup and cooling system startup tips
Those south of the equator are experiencing the opposite seasonal change and need to think about boiler winterisation and cooling system commissioning. In this case, boiler layup can be simplified by applying the VpCI Gecko, Boiler Lizard, or VpCI Dragon (depending on boiler size) to drained boilers and closing all openings to trap Vapour phase Corrosion Inhibitors within the space.
In many cases, the boiler can be restarted without product removal. Boilers undergoing wet layup can be treated with the VpCI Chameleon, a corrosion inhibiting blend that includes NSF G6 certification for use in food industry boilers where steam may come into contact with food.
The Cooling Loop Croc is the Boiler Egg’s counterpart for cooling system startup. It is an excellent option for both a full return to service and temporary startup during winter warm spells. The Cooling Loop Croc comes in water-soluble bags that can be added to a turbulent area of the cooling tower basin after partially filling the system with water and turning on the circulating pumps. The Croc dissolves and releases multi-metal corrosion inhibiting chemistry for the protection of both ferrous and yellow metals.
A valuable addition to the seasonal shutdown/startup checklist
Adding corrosion protection to the seasonal shutdown and startup checklist is a relatively small step that promises significant returns in terms of headaches avoided and repairs and replacements delayed.--TradeArabia News Service
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