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Castagra Ecodur 201: Coating 400 BBL welded steel tanks for Apache

Oil storage tanks in the 400-barrel range have been commonplace for decades in the oil patches of Texas and Oklahoma. Many have performed well but with the exposure to sourer crudes and acidic contents the erosion rates have sped up. Acidic water immediately attacks vulnerable steel where the original epoxy coatings have failed through a variety of causes.

One of the main problems with conventional epoxy coatings is their limited flexibility. They quickly micro-crack when exposed to wide temperature ranges that make steel contract and expand. But a coating comprised of vegetable oil and gypsum has been field tested for nearly a quarter of a century, maintaining exceptional adhesion and flexibility as well as acid resistance in frac tanks.

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Problem
The problem was simple. The job on five Apache 400-barrel tanks in Texas needed to be done quickly with a rapid return to service. Also, the coating needed to be completely VOC and solvent free for the safety of the workers.

The temperatures in the 50-degree Fahrenheit range were not going to be a problem and Ecodur composition meant it could be sprayed easily with no flash point risks. In fact Ecodur 201S has very high fire retardant properties and is also ANSI/NSF 61 rated for use with potable water, as it is also completely non-toxic. With that being said, applicators must follow strict safety protocols for its application, which include eye, skin, and breathing protection.

But for the few seconds that it is airborne during spraying, its pre-cure state has the potential to stick very aggressively to live tissue, hence the need for complete protection of potentially vulnerable areas.

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Solution
Ecodur 201S – and its manually applied product form, 201M – has a long history in tank applications with many hundreds of tanks of this size up to mega tanks coated successfully and speedily. It should also be noted that this coating is not only limited to internal application, as it has been used widely as an external coating and even in its foam form as a highly effective insulator.

Ecodur 201S in this case achieved a rapid tacky-free state in about 30 minutes. Because it has, for all practical purposes, no time limit on repair and touch up efforts, the applicators were able to ensure that any high-risk areas of the tanks were well coated.

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Application Results
24 hours after spraying each tank a final inspection was made and all were declared fit for service. The 24-hour period allows for full cure and for any anomalies to be found. On rare occasions these can include the occasional blister. This case again demonstrated the importance of the coatings being VOC-free and applied without the use of solvents either in the formulation, application, or cleanup. Solvent cleanup and disposal is very costly and a health hazard and as this case showed, it was something the client wanted to avoid, hence the choice of Ecodur 201S along with the other benefits of rapid application and the short turnaround for a return to service.