“Where the traditional, galvanized metal-clad cooling towers have done a good job at cooling process water, they have also been highly prone to corrosion and, therefore, frequent cleaning, recoating and replacement,” says John Flaherty, president of Delta Cooling Towers. In addition, the use of water treatment chemicals to maintain water chemistry can also cause faster deteriorating of the metal shell, says Flaherty.
Using plastic (high-density polyethylene or HDPE) as an alternative to galvanized steel might cost a little more than galvanized steel, but since HDPE isn’t affected by chemicals that cause oxidation, its lifetime will be much longer, and maintenance is less, says Flaherty. Plastic will survive more aggressive chemicals when they’re used to clean the towers. In addition, plastic can easily be molded so sharp corners usually associated with metal towers are gone. Flaherty says plastic towers outlive their galvanized counterparts such that his company places a 15-year warranty on them.