July 2015, Vol. 70, No. 7
Features
UV Becomes Complimentary Process To Conventional CIPP
Earlier this year, Underground Construction magazine’s 18th Annual Municipal Survey documented that cured-in-place-pipe (CIPP) lining is the “most used” trenchless construction method for rehabilitation of failing sewer piping infrastructure.
Some believe the use of CIPP liners cured with ultraviolet (UV) light will expand the market by offering additional and complimentary rehabilitation options. Already a major force in Europe, UV CIPP technology is generating considerable interest in the U.S, providing additional options for the ever-growing CIPP market
UV-cured CIPP is just one more step in the evolution of CIPP in the United States where water/steam cured liners have been used successfully for years.
Looking back at recent CIPP history, felt CIPP lining manufacturers and sanitary sewer service providers and contractors routinely using CIPP received a scare five years ago when federal government efforts succeeded in designating styrene – a key ingredient used in felt CIPP sewer liners – “a reasonably anticipated carcinogen.”
Styrene-free resin alternatives were costly, and many in the industry were concerned that project owners would be wary of continuing to use a product containing styrene.
Those fears proved ungrounded and CIPP continued to grow. While standards for styrene use may become stricter, there does not appear to be any immediate actions pending that would ban or prevent the use of styrene based resins. However, specific rehabilitation locations may dictate where specific resins can or cannot be used.
Something different
The state of the CIPP industry and significance of UV CIPP in the U.S. were discussed by two respected industry veterans:, Lynn Osborn, P.E., technical director of NASSCO (National Association of Sewer Service Companies) and owner of LEO Consulting; and Gerry Muenchmeyer, P.E., owner of Muenchmeyer Associates and former NASSCO technical director.
“Looking back,” said Osborn, “Insituform invented and patented the CIPP UV cure process. There were a few tubes installed in Europe in the 1980s and it was evaluated for the U.S., but cost-effectiveness was an issue. The process did not gain traction until the patents expired and other companies entered the UV cure market.”
Osborn said resins for CIPP cured with water and steam and UV CIPP are essentially the same, but a different initiator package is used for UV cure.
“All of the steps and equipment on the job site up through pulling the tube into place are similar for both UV cure and pull-in steam-cure CIPP,” Osborn continued. “However, the process of curing UV CIPP liner is totally different than for a water or steam cure inverted CIPP. Also, UV cure uses a totally different equipment package for curing the tube. Whereas steam and water cure require a boiler, UV cure has the light train and supporting equipment.”
Osborn cites “pros” for UV CIPP:
• Nice, clean process;
• Minimal styrene emissions;
• Extended wet out tube life of six months or more;
• High strength;
• No cure water or steam condensate discharge; and
• Short curing times.
“Cons” include:
• Size of pipes that can be rehabilitated is limited;
• Cannot cure thick wall tubes without adding an initiator for heat cure which reduces wet out tube life; and
• “Short” cure times may not be shorter than some steam cure processes.
The future?
“Water and steam cured CIPP is a huge business in North America with many, many installers and thus, prices have been driven down to the rock bottom,” Osborn said. “Water and steam cure CIPP have had momentum in the U.S. over the last four decades and it has performed well. This makes it hard for new processes to compete. Many customers are satisfied with the status quo, product and prices, and change is hard. “
In the immediate future, Osborn believes more CIPP installers will begin installing UV CIPP.
“Long-term,” he concluded, “I believe UV cure will develop a good market share, but it will be a real challenge for that market share to be as large as water/steam cure.”
Gerry Muenchmeyer provided a brief history of CIPP about water/steam cure CIPP and UV CIPP.
Traditional felt liner cured-in-place-pipe was initially developed using commercially available fabric and resin materials, said Muenchmeyer. It was effectively first installed in 1971 with cold water, then heating the water causing the resin to cure and harden thereby forming a new pipe within a pipe. Improvements in the technology over the last 40 plus years has included better materials, improved resins specifically designed for municipal, commercial and industrial applications, more efficient equipment and faster production and installation methods.
Environmental concerns of using and discharging large volumes of water, during installation and curing, caused the industry to shift gears and steam curing became popular, Muenchmeyer continued.
“Steam curing eliminated large amounts of water usage and installers improved both the efficiency and speed of installing a CIPP,” Muenchmeyer said. “Additional products were developed to enhance the physical properties or strength of a CIPP by adding reinforcing material such as fiberglass and carbon fiber to the felt liner thereby producing thinner yet stronger lining products for large diameter pipelines and pressure pipe applications.
“These and many other improvements allowed outdated pipeline systems to be rehabilitated at a lower cost and without major disruption to other utility and street infrastructure, and CIPP has since grown from its inception in the early 1970s to a multi-billion dollar universal technology embraced in all corners of the world.”
Steam shift
A shift in the rehabilitation market changed when the use of water became undesirable and steam curing was not applicable, he said.
“Opportunities for other technologies evolved,” said Muenchmeyer, “including the UV Curing process. UV had been used for many years on special projects but was not sufficiently developed to compete effectively with the felt liner industry in terms of either speed or cost.
“However, over the last 10 to 15 years, UV curing has improved and developed to where it can compete effectively with other technologies. Better and more intense lighting, improved material manufacturing and more efficient installation methods have spearheaded the growth of this technology in Europe and other parts of the world. It is therefore logical that a large market like the U.S. would attract technologies which have enjoyed success in the European and other world markets.”
Early in 2006, Reline America first launched a UV-cured lining system at the Underground Technology Conference (UCT) and the technology raised the curiosity of industry leaders who began to investigate and find out more about this new way of curing a CIPP liner. Was the technology competitive to the more well-known felt liner technology? Was it the same or better quality and would installations be faster and less disruptive? And, of course, where had this technology previously been installed?
“The answer,” said Muenchmeyer “was in the European markets where UV cured lining systems were being successfully installed, and the market for their use appeared to be growing. However, UV technology has not diminished the use of other liner systems, but has provided the industry with an alternative or complimentary method for rebuilding the failing pipeline infrastructure.”
FOR MORE INFORMATION:
NASSCO, (410) 442-7473 (PIPE), www.nassco.org
Reline America: (866) 998-0808, www.relineamerica.com
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