When Mukilteo Water District’s manager noticed that the urethane coating on a 20-year-old potable water tank was showing its age, he decided a cosmetic makeover was in order using new fluoropolymer technology from Tnemec. “The main consideration was aesthetics and lack of gloss retention,” recalled Tnemec coating consultant Scott McConnell. “This was a 3 million gallon tank, and right next to it was a 6 million gallon tank that was 10 years old. The district manager had some repair work done on the newer tank when he noticed that its shine was different from the older tank. He had a good example of how a standard urethane coating ages and how the shine changes over a 10-year period.”
The district had used Tnemec coatings exclusively on all of its potable water tanks, both inside and out, since the 1980s. The original exterior coating system used in 1985 consisted of Series 66 Hi-Build Epoxoline, a polyamide epoxy, and Series 71, a polyester polyurethane. “The manager wanted to extend the color and gloss much longer than he was currently getting with standard urethane coatings,” according to McConnell. “We recommended Series 701 HydroFlon, a fluoropolymer polyurethane, which surpasses the life expectancy of traditional urethane topcoats while providing superior color and gloss retention.”
Series 73 Endura-Shield, an acrylic polyurethane, was applied over the existing Series 71, followed by a topcoat of Series 701 HydroFlon. “They were able to empty the tank, recoat it and put it back into service in less than three weeks,” McConnell explained.
Due to the proximity of the tank to neighboring property, both Endura-Shield and HydroFlon were roller-applied at 2.0 to 3.0 mils DFT. “It was the first time the applicator, Coatings Unlimited, had used HydroFlon,” McConnell added. “The applicator liked the product a great deal, to the point that he promoted it on his next job.”
Incorporated in 1920, Mukilteo Water District provides water and sewer services to more than 6,500 customers in the area between the City of Everett on the north and Puget Sound on the west, and the City of Mukilteo on the east.