Pipe Shield’s water line repair system delivers epoxy by air

Researchers continue to develop novel methods of rehabilitating water distribution mains. Canada’s Pipe Shield continues to make its mark on the other side of the wall, using an epoxy system to rehabilitate the networks of smaller waterlines that serve end users beyond the watermains.

Pipe Shield employs a multi-step process to rehabilitate water pipes, beginning with site analysis using medical grade fibre-optic cameras to inspect the interior surface of the pipe and to determine remaining pipe wall thickness. Typical causes of damage include erosion, corrosion, over-chlorination and poor workmanship.

Pipe systems are isolated and then dried using a specialized air compressor. The target pipes are cleaned using microscopic garnet grit that removes corrosion. The grit is then collected and weighed at the pipe exit to ensure all material has left the system. A coating of ANSI-NSF 61 Certified Epoxy is applied to the interior of the pipe using the same compressor. While the epoxy coating is fully cured in about four weeks, the average return-to-service time for a treated pipe section is about eight hours.

Brad Arnold, technical consultant of Pipe Shield, has been researching epoxy pipe rehabilitation systems and conducting shop trials since 2001.

"The thing that struck me about the existing systems of that time was that you might achieve some results, but they didn’t work consistently," he says. "There was no application of the scientific method. With one method you actually had to listen to hear the epoxy go by as it was blown through the pipe."

Arnold worked with the National Research Council and Mark Knight, director of the Centre for Advancement of Trenchless Technologies, to develop a system that employed the laws of fluid dynamics to predictably distribute the epoxy coating through twist, turns, elevations, elbows and variations in pipe diameter. Once applied, Arnold says that the epoxy coating is more than 40 times as strong as the copper pipe it repairs. Accelerated aging tests conducted by the U.S. navy indicate that it provides an operational life of more than 50 years.

Pipe Shield’s air distributed coating system works for piping with at least 20 per cent remaining wall thickness and with diameters of between 3/8" and four inches.  An interior spray system is used for long pipe runs of two inches in diameter and larger.

To the uninitiated, the laws of fluid dynamics may appear counterintuitive. For example, as the diameter of a pipe narrows, it takes longer for the epoxy to line the interior of the pipe. That’s because, as the volume of air is reduced through the narrower pipe, so is the efficiency of the distribution.

"We recently developed a software simulation program for possible application in nuclear reactors that will show us precisely how to coat any complex piping system with epoxy," says Arnold. "Each year we spend between $200,000 and $300,000 in research and development to improve the application of the product."

Among the company’s signature projects is the water park at the Great Wolf Lodge Resort in Niagara Falls.

"When the last spa or whirlpool was being framed, a contractor unknowingly drove a reinforcing rod through the two-inch water feed that supplied the water park," says Arnold. "A contractor was called in and tried for two weeks to find that leak. They pulled large cameras through the pipe and damaged other pipes and pipe fittings. They called us on a Thursday, two weeks before the park was set to open. Our video probe found the holes and cracks in 20 minutes and by Sunday we had relined all of the damaged sections of pipe in time for the opening."

More recent projects include a series of student residential buildings at York University and two projects at Toronto’s Hospital for Sick Children.

"As a full service plumbing contractor, we’re happy to replace the piping if that’s what the client wants," says Arnold. "But clients who have done their due diligence often realize there’s greater value and less disturbance in having the pipe epoxy coated."