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Bolted Tank & Underground Water Tank Coated with Ecodur 201 (Ener-Spray)


Bolted steel tanks are one of the most enduring methods of storing liquids with great longevity and ability to hold up to 5 million gallons. Their fabrication remains almost as simple as when they were first built over a century ago. Technological improvements have largely focused on materials that ensure they do not leak or degrade from corrosive chemicals that are often contained in crude oils and production waters.

Galvanised tanks are assembled to one another on site using galvanized bolts. The tank shell sits attached to a concrete foundation. Sealing of the tank is usually a high-pressure curing mastic around the joints and bolt holes or with an internal synthetic rubber membrane liner. They are generally for storing water for fire sprinkler, potable water and irrigation markets.

This case study concerns two separate tanks at two different locations.

Tank 1 a 50ft diameter bolted water tank for Epcor in Alberta, Canada.

Tank 2 a 16ft diameter underground water tank. It was a corrugated galvanized steel wall with a concrete floor at The Crossing Resort in the Banff National park, Alberta, Canada.

Tank 1’s previous lining was worn. Without remediation, the steel would have deteriorated further and potentially to the point where it would not be economical to repair. Further complicating the project were the very tight deadlines. This meant all equipment, crew and materials had to be on hand for immediate application of the coating during optimum conditions. The client also wanted a high-performance coating that was free of Volatile Organic Compounds (VOCs) and was totally free of solvents, including for clean-up.

Tank 2 The tank was losing a large amount of water as the tank was heavily corroded with numerous holes, both small and large. It was the large holes which presented a particularly serious challenge. Any coating used had to be free of any chemicals that might contaminate the water.

Ecodur was chosen for both cases as it is VOC-free, BPA-free, and completely non-toxic and biologically inert. In the case of the water tank, Ecodur’s NSF/ANSI Standard 61 rating for use with potable water, made it the ideal choice on all counts.

Tank 1 Ener-Spray sand blasted the steel and ensured it was dry with no flakes.

They spray coated Ecodur 201S on the floor of the tank and with an additional coating 4ft up the wall from the floor. The base of the tank is where water can collect, often contaminated with chemicals that attack steel. This four-foot band of extra protection has been shown to be highly cost-effective for long term protection.

Tank 2 The tank was sandblasted revealing many small holes and a few large ones. They were easily sealed with Ecodur 201s and the large holes were sealed using fiberglass sheets and thoroughly impregnated with Ecodur ensuring a strong bridge over the hole. Again, the client wanted extreme longevity and performance from the coating.

Application Results

Tank 1 The project took 4 days to complete. The final inspection included a hydro test and all proved satisfactory, allowing the tank to be returned to full service immediately.

Tank 2 Again, flowing a satisfactory inspection the tank was returned to full service and the client expressed total satisfaction at having a highly economical solution for a problem that could have led to the tank being replaced.