CoatingsPro Magazine

MAY 2015

CoatingsPro offers an in-depth look at coatings based on case studies, successful business operation, new products, industry news, and the safe and profitable use of coatings and equipment.

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After two coatings failed on this 25-year-old 200,000-gallon (757,082 L) wastewater tank, this food processing facility decided it was time to try something else. The client called in Carolina Management Team (CMT) to fix it! Feature 48 MAY 2015 COATINGSPROMAG.COM BY JACK INNIS, CONTRIBUTING EDITOR PHOTOS COURTESY CAROLINA MANAGEMENT TEAM, LLC T here's simply no way to sugarcoat this. A failed polyurea liner on a wastewater tank cost a North Carolina food processing company more than a million dollars! Te nightmare began years ago when a 200,000-gallon (757,082 L) tank that receives discharge directly from the plant foor suddenly sprouted a spray nozzle-type leak. Te 25-year-old steel-walled tank sits frst in a series of vessels that condition wastewater charged with food components, such as batter, eggs, milk, sugar, and fruit juice. Te tank is always in use and went uninspected for years. "Due to the nature of the tank, we couldn't take it down to inspect," said a company supervisor; the company prefers to remain nameless. "Te liquid level would rise and fall, but there was no way to inspect below the liquid. Tat was our biggest problem." As it happened, years of harsh wastewater (with an average pH value of 3–4) undermined the old coal tar coating, chewed through the steel in places, and created the leak. Te tank needed major welding and a new coating system. Plans were made, bids sent out, and a feet of mobile wastewater tanks trucked to the site. Te food processing company brought the mobile tanks online and drained the damaged tank. A coatings contractor removed the worn-out coal tar liner, welded a steel repair girdle into place, and spray-applied a polyurea liner to the interior. Everything looked peachy at frst. But something was about to go terribly wrong. Six months later, the polyurea started peeling away. Small chunks and king-sized sheets of failed coatings clogged the tank 's drains, jammed its mechanical aerator, and caused other problems. With nowhere for the wastewater to go, the company had to close the plant down temporarily. Te contrac- tor returned and installed a new polyurea system. Within a year, the second coating failed. Te string of temporary closures ultimately cost the facility one full day of production, which equates to one million dollars in lost revenue. Wastewater Tank Fix No Cakewalk! TANK STEEL POLYURETHANES

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