(This article was originally published October 3rd, 2017 in TrenchlessTechnology.com)
Every job, big and small, usually presents one or two unexpected challenges to a contractor. This is normal. But then there are jobs that test the limits of current technology and require a contractor or manufacturer to improvise new techniques of application that have never been attempted or been needed before.
Precision Trenchless LLC of Schenectady, New York, completed such a job earlier this summer at a chemical plant in upstate New York. As part of a major renovation to its facilities, the client had contracted with Precision several years ago to rehabilitate its aging chemical wastewater pipes that had been originally installed with the plant back in the 1950s. The pipe to be lined varied from clay to PVC to iron. Precision had gotten the job because it could reline the pipes with a pulled-in place chemically-resistant, non-VOC liner that could also withstand high temperatures.
Precision is a licensee of Montreal-based Formadrain Inc., which had developed the special industrial resin to be used on the project. Its FORMAPOX 301 resin has demonstrated that it resists almost any acid and can be used in process pipes running basic liquids (e.g., caustic) at temperatures up to 212 F. The FORMAPOX 301 resin and lining system has been used successfully to rehabilitate process water pipes for companies such as MolsonCoors, Coca-Cola, PPG, Anheuser-Busch, Lassonde, among others.
“While the majority of pipes to be lined were 4 to 12 in., what made this job a test of current technology is that it included the lining of 131 ft of 36-in. pipe, plus another 18 ft of 24-in. pipe carrying the company’s chemical wastewater plus steam to its water treatment plant,” says Precision senior project manager Lynne Farrell. “I knew of no technology, including that of Formadrain, that had ever attempted lining such monsters that also carried such caustic and high-temperature contents.”
As a result, Farrell consulted Carl Marc-Aurele, Formadrain’s technical support engineer. “I am not sure but I think Carl thought I was a little crazy at first but said he’d work with me on it,” says Farrell.
None of Formadrain’s licensees had ever attempted to line such large industrial pipes carrying such contents. The Formadrain CIPP system is ideally suited to lining laterals and doing spot repairs on 4- to 12-in. pipes. It lines multi-diameter transitions, elbows, and bends without special handling and its FORMAPOX 301 resin had already demonstrated its ability to handle high temperature and caustic process water for numerous clients.
But Marc-Aurele knew that to attempt such a job, new techniques of application would be needed. This included the manufacture of monster mandrels about which the lining would be wrapped, then inflated with steam to cure the liners when moved into place.
After the smaller diameter pipes had been completed, the Formadrain engineer traveled to the plant in June to help Precision’s crew with the lining installation on the large clay pipes. The job, which was under a time constraint, took seven days.
The scale and difficulty of the job required six to seven crew members outfitted in full personal protection equipment to do the wetout with a full crew of up to 15 to move the liners in place.
The maximum length of liner to be done at any one time was determined to be 14 ft due to resin weight restraints. But even with this short length, a fully wetted-out liner weighed 450 lbs and required a pallet jack and large forklift to move it to the insertion point.
Marc-Aurele says, “A lot of preparation was also done prior to the project (measurements, cleaning, camera, cutting fiberglass and resin schematics, etc.) for it to go as smoothly as it did. But it did not go 100 percent right as we had to scrap the first insertion because it bunched up in several places and could not be righted. We also had some scale up problems with quantities.”
So besides keeping the liner short, another fix had to be found and implemented to stabilize the liner to keep it from slipping and bunching as it had done on that first install. The weight plus the length of the liner made this critical because even though the liner required steam pressure to cure, the resin started to go off on that first install due to the extraordinary length of time that was being taken to try to unbunch it.
Even with these precautions and techniques, heavy rains caused a flow that pushed the mandrel on one lining insertion so that the liner missed overlapping the one previously installed. There was supposed to be a one-foot overlap on liner sections. Because of the miss, a point repair had to be done.
One saving grace of lining these monster pipes is that they were, for the most part, a straight horizontal run with only one section having a curve. But there were other challenges thrown in. There was a day on the site when there was no electricity because the plant was shut down. There was another day when there was no water.
However, it got done and on schedule, despite the initial misgivings it could be done at all.
“As much as we planned it out ahead of time and on paper for weeks and months, thinking through every possibility; with the time constraints involved and the fact that something of this magnitude had never been done before, I still ended up crossing my fingers a lot on this one,” says Farrell.
Marc-Aurele praised Precision’s crew. “All parties involved reacted quickly which ensured the success of the project. It was an unprecedented project (in size) and unprecedented diameter in such long lengths (and therefore weights, friction, workforce etc.) in such sizes for Formadrain.”