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Adding aesthetic appeal water tank protective coatings.

While the University of Notre Dame has certainly contributed to the fame and fortune of South Bend, Indiana, a recent addition to the city's landscape has created its own unique interest. The newly constructed, 157-ft high water storage tank tower is fast becoming an icon for South Bend, symbolizing the city's commitment to industrial development and growth. "The construction of the water storage tank was part of a master plan that forecasted the need for an elevated water supply because of increased industrial and residential development in South Bend's northwest area," says John Wiltrout, Director of Treatment, the South Bend Water Works. "This is a very appealing area for business and industry, and the tank is working like a beacon to bring in new growth."

Wiltrout is responsible for all water treatment activities from operations to maintenance and handles reporting requirements to the Indiana Department of Environmental Management. The 27-year veteran says his job is to ensure compliance of the water quality standards for the distribution system, while meeting the consumption needs of all users.

The $2.36-million water storage tank project includes the land, roadway, engineering, and tank and was designed, erected, and painted by Chicago Bridge & Iron (The Woodlands, Texas) during the summer of 2002. The 1.5-MG spheroid tank quenches the water needs of the city's 107,000 residents as well as its industrial and commercial users. The presence of the water storage tank is complemented by the colorful, aesthetically pleasing Sherwin-Williams (Cleveland, Ohio) protective coatings that were applied to the structure last summer.

While there are other tank storage designs which utilize several structural "legs" for support, the spheroid shape is constructed with a single giant leg support and was selected because of easy maintenance. "There are no hidden places or crevices where I-beams connect and moisture can collect creating an environment for rust to form," says Wiltrout. "The spheroid design makes painting easier and the structure looks nice as well."

AESTHETIC APPEAL

In the past, water storage tanks were coated in traditional shades of gray or other neutral colors with little thought to aesthetic appeal. But in today's diverse, colorful world, non-traditional uses of color are popping up all over on bridges, health care and manufacturing facilities, and commercial properties. So, why not water storage tanks that are visible for miles?

The South Bend Water Storage Tank averages 22 mgd. During peak summer months, consumption jumps to almost double that amount--44 mgd. To help ensure a continuous supply of quality water throughout the year, protective coatings were applied that would meet the ANSI/NSF-approved Standard 61 for potable water storage tanks and Federal EPA requirements.

Because parts of the fabricated steel water tank sat in storage for an extended period of time, a sweep blast of the exterior sphere material was performed. About 50 to 60 percent of the steel's surface was blasted back to bare metal and then power washed to prepare the steel's surface for a primer coat, according to Chicago Bridge & Iron's paint supervisor, Dave Hartman. Corothane[R] I Mio-Zinc Primer was applied as the outside primer because of its resistance to rust and corrosion. It is a two-component, VOC-compliant, moisture curing urethane with micaceous iron oxide, designed for low temperature application to blast cleaned steel surfaces.

"This primer can be applied at temperatures as low as 20 degrees F on steel where resistance to rust or corrosion undercutting is required," says Paul Quinlan, Sherwin-Williams Industrial and Marine representative for the Fort Wayne, Indiana area. "The primer is also used commonly as a spot primer in the field for touch up applications."

Exterior surfaces of the water tank and the interior "dry" surfaces (the mechanical room which houses all the electrical equipment, pumps, feed lines, and ladders) received a single primer coat of Corothane[R] I Mio-Zinc Primer at five to six mils wet film thickness. The primer is dry to the touch in about 20 minutes at 77 degrees F with 50 percent relative humidity and can be re-coated in four to six hours.

The interior of the water storage tank received two coats of the manufacturer's High Solids Catalyzed Epoxy at five to six mils dry film thickness and included coating the "wet" interior surface area, which is the actual bowl of the spheroid tower where the water is contained.

"This polyamide/bisphenol epoxy resin coating is formulated especially for immersion service in fresh, salt, and potable water," says Quinlan. "This epoxy was selected because it is an approved coating certified to the ANSI/NSF 61 Standard for use in potable water storage tanks and meets Federal EPA requirements."

Next, the intermediate coat, Macropoxy[R] 646, was applied to the exterior of the water storage tank. The high solids, high-build, fast drying polyamide epoxy provides coating protection to sharp edges, corners, and welds and will prevent rust forming through to the tank's surface. Certified to the ANSI/NSF 61 Standard, the intermediate coat was applied at five to six mils dry film thickness in a light blue color.

LASTING FINISH

While the colorful coatings on the water tower provide wonderful visual interest, they also serve a practical purpose. Designed for use in industrial environments, SherThane[TM] 2K Urethane, a chemical and abrasion resistant aliphatic urethane enamel, was applied as a topcoat at two to four mils in a dark blue color, providing very good color and gloss retention.

"The dark blue color will help hide the potential mildew and algae that may form on the bottom of the water bowl which is shaded from direct sunlight and heat," says Quinlan. "Generally, the bottom of the bowl is cooler and tends to accumulate moisture and sweats."

The final coating was Diamond-Clad[TM] Clear Coat Urethane applied at one to two mils dry film thickness to preserve the tank's fresh-painted appearance and resist color fading. "After a period of time, any coating will start to deteriorate and lose its color, gloss or protective properties," Quinlan says. "Diamond-Clad[TM] Clear Coating extends the service life and exterior weathering properties of the urethane coating, while enhancing the color and gloss of the finish."

The end result is a structure that looks great in its environment, but more importantly, resulted in a high level of customer satisfaction. The South Bend water storage tank represents a growing trend to transform large civic projects into aesthetically pleasing structures, and serves as an excellent example of how experienced color stylists can assist professional customers and industrial accounts with their graphic design and color needs.

A year later, the colorful coatings on the South Bend water storage tank are as crisp and true as they were last summer, still complementing the city's efforts to attract new business and industry to the area.
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Publication:Public Works
Date:Aug 1, 2003
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