UV Cure Provides Solution For CIPP Repair

July 2012, Vol. 67, No. 7

The Knoxville Utilities Board knew cured-in-place pipe (CIPP) would bring faster, lower-cost repair to an underground sewer pipe in Knoxville, TN. The 8-inch diameter clay pipe had been in service for more than 50 years.

When the pre-installation video showed active leaks in the pipe, engineers were concerned how the deterioration might affect a traditional CIPP liner. With traditional CIPP, the new liner is impregnated with resin that chemically cures, or hardens, into a solid when exposed to heat. Active leaking creates cool spots where potentially incomplete cure can result in lower mechanical properties.

Engineers decided to have the pipe repaired with BLUE-TEK ultraviolet cure technology from Reline America Inc. The fiberglass fabric liners for the job were impregnated with Vipel unsaturated polyester that AOC Resins formulates for UV cure. Because the resin hardens when exposed to UV light instead of heat, BLUE-TEK impregnated liners are not affected by cool spots. These liners can also be shipped without refrigeration, unlike liners which cure when exposed to heat.

“When Knoxville Utilities Board engineers heard that our liner was not affected by active leaks, they decided to use our technology for a pilot project,” said Danielle Verderame, marketing coordinator for Reline America. “The project site was located in a combination residential and industrial area that has very limited access, lots of trees and is close to buildings. Open cutting and pipe bursting would have been expensive and disruptive options.”

The pilot project for 2,991 feet was awarded to Portland Utilities Construction Co. LCC (PUCC). PUCC has years of experience in pipe bursting methods but had yet to perform a CIPP repair. Mike Woodcock of PUCC explained how Reline America technical support and AOC resin quality helped turn the pilot project into a new capability for PUCC.

“Reline America did an outstanding job in training our crew,” said Woodcock. “Their team helped us thoroughly learn the technique and become knowledgeable about the equipment and technology.

“The liners were impregnated with the AOC resin under controlled conditions in Reline’s ISO-certified facility,” Woodcock continued. “The AOC resin did everything that was expected – reacting smoothly during installation and performing very well in the finished liner.”