CoatingsPro Magazine

MAY 2016

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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COATINGSPRO MAY 2016 59 Science Behind It The Inside (and Outside) Scoop of Tank Coatings By John Anspach, Technical Director and VP Operations at Induron Coatings, LLC H igh-performance industrial coatings vary widely. Numerous products exist, and each one is designed for a specifc function. Tank structures, particularly those designed to store potable water, are a good example. Because the interior and exterior of the structure present unique coating challenges, they each require diferent performance requirements from the coating system. Te Papillion steel and concrete tanks are a great example of these diferences. The Steel Interior To properly coat the inside of the tank, the contractors on the Papillion's elevated steel tank started with a two-coat system using Induron PE-70 epoxy, which is more tolerant to the colder weather found in Nebraska. Tis system ofers excellent adhesion to the metal substrate and has very low vapor permeability due to a tight cross-link density, which results in superior resistance to water and other chemical environments. Likewise, this self-priming system is certifed by the National Science Foundation (NSF)/American National Standards Institute (ANSI) International for potable water. Te system also provides an ideal inert and safe barrier coating with no extractables afecting the potable water storage. The Steel Exterior Because the outside of this tank was being repainted, some remaining yet sound areas of coating remained on the structure. Terefore, a coating with superior adhesion was necessary. Induraguard semi-gloss epoxy system is a surface-tol- erant system designed for marginally prepared surfaces, including rusted steel, weathered galvanized steel, and most existing cured coatings. Induraguard is specifcally formulated for corrosive and abrasive environments. Its superior surface penetration combined with the epoxy amine chemistry allows the coating to penetrate sufciently into the surface profle as it cures. Tus, the product provided a ftting coating substrate for the Papillion tank 's subsequent systems, which were also designed to protect the outside surface. On this project, the tank exterior was fnished with Indurethane 6600 Plus. Tis product is an acrylic aliphatic polyurethane system, which is a formula designed for long-term surface protection. Not only does Indurethane 6600 Plus possess gloss and color retention, but it also ofers chemical and stain resistance. Tis means the coating can perform in aggressive environments, especially where splashes and spills are a concern. And lastly, because Indurethane 6600 Plus is designed to inhibit the growth of mold and mildew, it will preserve the Papillion image over time. Concrete Protection Another layer used on the exterior concrete was Induron's AC 403 Acrylic Elastomeric coating. Tis coating system is formulated with 100 percent acrylic resin and is used to fll and bridge hairline cracks. With an elongation capability of more than 100 percent, this coating formula will provide long-term protection against wind-driven rain and alter- nate freeze-thaw cycles. Te coating system will expand and contract to minor substrate movements, even at below-freez- ing temperatures. Te coating's acrylic chemistry resists ultraviolet (UV) rays from sunlight, but it will still allow the flm to " breathe," which allows moisture to freely escape from the substrate. Lasting Impression Determining what coatings are appropriate for a variety of substrates — concrete and steel, interior and exterior — is a crucial part in repair projects. Overall, the use of the difer- ent coating materials used on the Papillion tank project combine to create a protective system that should last for years to come. CP

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