Tower transition ...

In a project that took place over the past month, the City of Waukon water tower located on the north side of town within the Allamakee County Fairgrounds was sandblasted, sealed and repainted by K&W Coatings of Elkader both on its interior and its exterior as a maintenance measure. The photos above show the transformation from prior to any exterior work being started (left photo), to having its riveted seams sealed following sandblasting and preparing the exterior for sealing and painting (center photo), and the finished exterior with new lettering and more of a matte finish (right photo).

Stan Wagner of K&W Coatings explained that the interior coating for the water tower is a solvent-free aromatic polyurethane, brand name “Polibrid”, which is similar to liners used in pick-up truck beds. It is applied with plural component spray equipment. The compound begins as two separate components, resin and catalyst, heated to 100-110 degrees to equalize viscosity before being mixed by two static mixers in the 1/4-inch applicator line. Wagner said once mixed the material will set rapidly and is very effective in older riveted  tanks, as it remains flexible and can fill or bridge gaps and will even tolerate movement of joints without cracking. Wagner said 140 gallons of coating were applied to the tank interior.

The exterior coating is a three-coat system, according to Wagner. The prime coat is a zinc-rich aromatic urethane which provides outstanding corrosion protection, with Wagner explaining the zinc acts as a sacrificial metal, when the coating is damaged the zinc will oxidize more rapidly than the substrate and the zinc oxide produced will essentially “heal the wound”. He said an epoxy was used for stripe coating of the seams and rivets to ensure coverage (center photo above). The intermediate and finish coats are both acrylic polymers, the intermediate having corrosion protection and bonding properties and the finish coat has UV protection and color/gloss retention. Wagner noted the zinc and acrylic coatings are “dry fall” products that can be safely spray applied because they dry within a few feet after leaving the spray gun and will not adhere to surrounding objects.

The water tower was isolated and drained by consumer use prior to the project getting underway, with no interruption in service. According to City of Waukon Water Superintendent Jim Cooper, consumers normally served by the water tower located in the north portion of Waukon were serviced by the remaining water tower located in the south portion of Waukon and the City’s underground storage tank system connected to high pressure pumps. Standard photos by Joe Moses.
 

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