July 1, 2010

New Coating System Extends Life of Cooling Tower

By Sherwin-Williams, Cannon Sline Industrial, and OTB Technologies

Inspect, Don’t Expect

Another key team member was OTB Technologies Inc. of Phoenix, Ariz., the project’s independent third-party inspector. OTB personnel were on site 12 to 16 hours per day during application. “We kept ambient temperature records throughout the day,” said OTB Partner Jerry Colahan. “We used infrared thermometers to measure temperatures around the interior surface, sling psychrometers, and a DeFelsko Positector DPW [dew point meter] to measure the relative humidity and dew point. It was early spring, and it was critical for the surface conditions to be right for complete application.”

OTB Partner Randy Glover cited access to the surface as a primary issue. “It was my biggest surprise on this project,” he said. “There were only two ways to inspect the surface: from 60 feet high to 135 feet high, we could inspect using a man-lift, but from 135 feet and up, we had to go up in a crane basket over the top from the exterior or on a swing from the interior of the tower. It was time-consuming and required constant communication with representatives of the contractor, AEP, and the basket controller and crane operator, but we had to stay close to the edge to do our jobs and make certain that any pinholes were discovered and repaired.”

Sherwin-Williams provided on-site technical support throughout the project and provided just-in-time material delivery. Even though the project faced one of the wettest springs in Ohio Valley history—nearly 17 days of the nine-week lining and coating schedule were lost to rain—the project was completed on time and the tower returned to service on schedule.

“Our goal was to provide a new interior that would extend its overall service life,” said Bob Johnson, Sherwin-Williams market director, power generation. “This tower was in service for over three decades, and, while this project was not inexpensive, it’s certainly more cost-effective than replacing a cooling tower.”

—Contributed by Sherwin-Williams, Cannon Sline Industrial, and OTB Technologies.