‘Spot, spot and full’ tank maintenance: the alternatives

Dwayne Lum at Carboline explores alternative storage tank coating maintenance methods that balance cost, service life and environmental responsibility Corrosion is the intractable foe of carbon steel storage tanks. Experts rightly devote considerable attention to critical areas such as internal linings, cathodic protection for tank bottoms and external floating roofs as maintenance in these areas requires taking the tank out of service. Less attention, however, is paid to tank exterior coating maintenance because this can be undertaken without a service outage. And,  unfortunately, that lack of industry focus leaves savings on the table. The most common protective coating system for tank shell exteriors today consists of an inorganic zinc primer, an epoxy intermediate and a polyurethane finish. The inorganic zinc primer provides galvanic protection, the epoxy intermediate acts as a barrier and the polyurethane finish protects the epoxy from ultraviolet degradation. For a while. Quality coatings properly applied can provide over 15-20 years of corrosion protection before first maintenance. Even if corrosion does emerge and become widespread, it seldom threatens the...