UV Cure Provides Solution for CIPP Repair

19 April 2012

The Knoxville Utilities Board (KUB) have installed cured-in-place pipe (CIPP) to an underground sewer pipe in Knoxville, Tennessee, US.

When the pre-installation video showed active leaks in the pipe, KUB engineers were concerned how the deterioration might affect a traditional CIPP liner. They explain that 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. The 8-inch (203 mm) diameter clay pipe had been in service for more than 50 years and KUB expect the CIPP to bring faster, lower-cost repair.

Engineers decided to have the pipe repaired with BLUE-TEK ultraviolet cure technology from Reline America. They explain how 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 KUB 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.”

According to KUB, the pilot project for 2,991 feet (912 m) was awarded to Portland Utilities Construction (PUC).  They say that PUC has years of experience in pipe bursting methods but had yet to perform a CIPP repair.  Mike Woodcock of PUC explained how Reline America technical support and AOC resin quality helped turn the pilot project into a new capability for PUC.

“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.”

KUB say the first installation was so successful that right after the pilot phase was finished, they added 6,533 feet (1,991 m) to the project for a total of 9,524 feet (2,903 m).  PUC continues to get more UV-cure CIPP projects, including work under Phillip Fulmer Way, a busy street near the University of Tennessee football stadium and basketball arena where any manner of excavation can cause major disruption.

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