CoatingsPro Magazine

JAN 2019

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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Page 84 of 108

84 JANUARY 2019 COATINGSPROMAG.COM Never Again A wastewater clarifier started blistering only three years after put in service. By Rick Huntley, SSPC PCS, Senior Coatings Consultant, KTA-Tator, Inc. The Case of the Blistering Clarifier Coating System S ometimes, the culprit in a coating failure is something that you assume isn't there. A few years ago, a city in the Midwest decided to construct an additional wastewater clarifier to the three that were already in operation in their water treatment plant. e new clarifier was designed to have concrete walls and floors and carbon steel rake arms, troughs, and other associated equipment. e carbon steel equipment was coated in a shop with a weld-through primer and shipped to the location for installation. e field painter abrasive blast cleaned the steel components in accordance with NACE No. 2/Society for Protective Coatings (SSPC) Surface Preparation (SP) 10: Near-White Blast Cleaning at a location immediately adjacent to the clarifier. e specification allowed the contractor to select a coating system from one of three different manufactur- ers for application in submerged areas and required that any coatings used in the water supply system have NSF or UL certification. e specification required that three coats of whichever manufacturer's system was chosen had to be applied at an average thickness of 5 mils (127.0 microns) per coat. e coating manufacturer selected described the coating as a volatile organic compound (VOC)-compliant, 80 percent solids epoxy coating that was formulated for pipes and tanks containing, among other things, potable water. An earlier version of the product data sheet included a recom- mendation for use of the product in Photos courtesy of KTA-Tator, Inc. An earlier version of the product data sheet included a recommendation for use of the product in water treatment tanks, but that recommendation was not contained in the latest version published before the start of this project.

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