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Ecodur 201: Coating Crestwood Tanks (Coatings Specialties)

North Dakota has some of the severest climatic conditions of anywhere in the Lower 48 and the fracking industry there bears the brunt of them, especially when it comes time to refurbish tanks that cannot be kept out of production for long periods in winter when perfect coating conditions are usually required for conventional coating products as they simply cannot be applied during prolonged deep freezes. North Dakota temperatures can fall as low as – 60 Fahrenheit (-51 C) and include frequent blizzards.

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Problem
Crestwood needed to coat a 200,000 BBL, 198-foot diameter tank during the winter period in Keene, North Dakota. It had been field erected and comprised of welded steel plates that are highly vulnerable to corrosion if not adequately coated quickly.

The area to be coated totaled about 37,000 square feet and included the floor and a wall height of 10 feet to provide full protection against the crude oil contents which inevitably lead to an accumulation at the bottom of a tank of water containing a variety of chemicals that can attack steel, making the bottom of the tank especially vulnerable.

The climatic conditions also highlighted the need for a coating that would remain highly flexible throughout its life as summer temperatures can go as high as 121 Fahrenheit (49C) in North Dakota, causing significant expansion and contraction of the steel plate.

Conventional epoxy resins are highly prone to micro-cracking, especially along weld seams, allowing for the ingress of steel-attacking chemicals. Ecodur 201 has double the flexibility of conventional epoxies throughout its lifespan, and has the additional important benefit of being rebondable on existing coatings for an indefinite period should repairs ever be required which is not infrequent in the fracking business.

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Solution
Ecodur 201S was primarily chosen for its winter performance advantages. Ideally, the application of Ecodur 201 should be at least 10 degrees F or 5 degrees C above the dew point at the time of application onto a dry surface to avoid the potential of trapping moisture. But, it being non-toxic, virtually odorless, VOC and BPA free, combined with the fact that solvent use is avoided completely, were further important considerations.

Conventional epoxies frequently require the use of solvents, especially for clean-up and the disposal of solvents is a highly regulated and expensive undertaking.

Ecodur spraying requires, as with the spraying of conventional coatings, standard safety gear use as while the droplets of Ecodur are airborne, they are highly reactive human tissue. However, Ecodur has another big advantage of setting up rapidly and being tack free within an average of 30 minutes and can allow workers to walk across it within two hours in all but the severest of cold conditions with a return to service of the tank within 24 hours and not two to three days for conventional coatings.

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Application Results
The project was carried out by Coating Specialties and, in the event, the coating was not done until June. The weather, however, still provided challenges with the threat of heavy rainstorms, but it did not delay the work as a satisfactory weather window of opportunity was exploited and Ecodur’s quick-curing abilities ensured a satisfactory result within the short period of time.

A 24-hour final inspection, including a check to see that the 201S had been applied to a depth of 20-30 mils, showed no anomalies and the interior was passed for immediate use as crude oil storage.

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