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2006 ACEC Honor Award

Water Tank Reconditioning Case Study
Owner: City of Anoka, MN

SEH, in partnership with the City of Anoka, nationally recognized paint manufacturer Sherwin Williams and a qualified contractor, conducted a case study of a new single-coat organic zinc called Galvapac on the City’s 400,000-gallon water tank.

Corrosion caused by coating system failures is a huge problem in water tanks. Traditional coating systems call for multiple layers of epoxy or a zinc-based paint with an epoxy topcoat to protect the tank from the corrosive effects of their humid interior environment. SEH’s test case put these two traditional coating systems up against a new NSF 61-approved single-coat organic zinc paint (Galvapac) from Sherwin Williams.

The interior design of the City of Anoka’s tank, which consists of a roof support system of intermittently welded structural angles connected to a center compression ring, made it an excellent testing candidate. Lapped roof plates and spacing between welds makes painting in these tight areas difficult, which often results in rustbleed and premature corrosion failures.

Following a two-year warranty inspection, testing indicates no substantial difference among the systems. If results remain positive, the single-application method has the potential to save municipalities across the country thousands of dollars in water tank painting labor and material costs over the multi-coat systems.