Curran International Inc. (www.curranintl.com), a coatings application provider serving the global power, petrochemicals, HVAC, and shipping industries, has developed what it describes as a newer, faster, and more flexible method for applying polymer-based protective coatings to tubing in condenser water boxes operating in power plants. The new technique deploys a “flex-lance” apparatus that extends as much as 60 feet down the tubing within a small water box.
The technique, incorporating thin-film applications technology patented by Curran International, facilitates full-length tube coating from “inside the box” without disassembling waterboxes or headers. This solution, according to Curran, enables in-situ cleaning and coating of corroded condenser tube IDs at a fraction of the cost or schedule requirement of retubing.
“Our innovative technique for cleaning the interior walls of small-diameter tubes in condenser water boxes gives plant managers one less headache to deal with,” said Ed Curran, chief executive officer of Curran International, in a prepared statement. “The flex-lance application technique can then coat even the most obscure spots inside the tubing in the heat-transfer equipment, preparing the surface walls with a grit-blasting technique as well.”
The new flex-lance system uses patented applications technology for applying coating to full circumferential wall of tubes typically one inch of less in outer diameter. The flex-lance system can be passed through a 18-inch manway at the waterbox or header; once set up a technician can coat full length tubes to 60 feet in length. A thin film (<.003”) of polymer lining is atomized and driven onto the inner surface of the full length tube as the lance travels down the tube. The application has been used to recover corroded condenser tubes at several power plants. In one application, a steam ship condenser with failing tubes was repaired with coating in less than 10 days.
Tube cleaning to “white metal” is a surface-preparation standard required before applying protective thin-film coatings. The coatings application improves resistance to corrosion, fouling, and other common tubing blockages. This treatment also drastically reduces plant shutdowns and equipment stoppages for required maintenance and cleanings, positively impacting operational efficiency, asset utilization, and equipment performance. According to Curran, the use of thin-film linings has saved energy, petrochemical, and power generation clients millions of dollars annually in extra energy consumption and maintenance costs by improving the performance of fixed equipment running cooling water.