Although plant officials at a Texas refinery have been protecting their steel storage tanks for years with exterior coatings from Tnemec, it wasn’t until 2007 that the company’s interior high-build epoxy linings were used there for the first time. “The contractors applied the interior coatings on a few smaller tanks and were so impressed they basically said they didn’t want to ever use anything else,” according to Tnemec coating consultant Eddie Borne. The lining system has since been used on a 270-foot diameter petroleum storage tank, which required more than 2,000 gallons of coatings.
The primary product used was Series 350 Tank Armor, a high-build epoxy lining that offers excellent chemical resistance. The liner was spray-applied at 30 mils dry film thickness (DFT) using a Graco Xtreme plural component proportioning pump. Surface preparation was in accordance with SSPC-SP5/NACE No. 1/ISO SA 3.0 White Metal Blast Cleaning, with a minimum angular anchor profile of 2.5 to 3.5 mils.
The refinery’s tank coordinator for coatings and linings has since announced his intention to use Series 350 for all internal steel tank relining projects scheduled through the first half of ‘09. “He liked the product’s flexibility, its application properties and rapid curing time,” Borne acknowledged. “He also liked the fact that it resists a wide range of chemicals typically stored in these tanks. When he walked in the tank the next morning and saw the bright, glossy and smooth finish, he was convinced he had made the right choice.”
Contractors also applied Series 351 Tank Armor, a specialized polysulfide/novolac epoxy repair and base coat putty for seams, rivets and chime area of the tanks. “Series 351 is used at the floor-to-wall transition to increase the surface area of the radius so that all the stress isn’t coming in that sharp corner, but is spread over a larger area,” Borne explained. “Series 351 prevents cracks from developing in the Series 351 liner, which protects against chemical attack from a wide range of petroleum products, fuels, gasohol, waste, alkalis and organic and inorganic acids.
On smaller steel storage tanks containing sulfuric acid solutions, alkalis and solvents, Protherm spray-applied Series 365 Tank Armor, a novolac epoxy lining, at 40 mils DFT. “The applicators thought it was the best product they’ve used for lining acid tanks,” Borne noted.
“Since all Tank Armor products are 100 percent solids, they don’t contain solvents like many other liners,” Borne added. “Because there is no risk of solvent entrapment from epoxy tank linings applied at high-film build, the occupational, health and safety issues are minimal.”
Tnemec coatings were also used on the exterior of the refinery’s steel storage tanks and include Series 30 Spra-Saf EN, Series 66 Hi-Build Epoxoline, Series 90-97 Tneme-Zinc and Series 1074 Endura-Shield II.