Trenchless repair and rehabilitation methods are also oftentimes more cost-effective than the excavation and replacement of buried pipes. Due to the success of CIPP rehabilitation in sewer lines, industrial companies are beginning to embrace the technology for rehabilitation of process piping systems.
Recently, Veit, a specialty contractor located in Rogers, Minn., and a licensee of CIPP Corp., Hudson, Iowa, used CIPP technology to rehabilitate the fresh water main of a large upper Midwest industrial facility. The industrial nature of the application, combined with the location challenges and unique construction of the pipe, makes Veit’s use of CIPP a noteworthy project to detail.
Veit’s bid for the project called for the rehabilitation of a fresh water supply line used to feed the process cooling system at a large industrial facility in the upper Midwest. The 34-in. diameter wooden pipe was built and installed in the early 1900s and is reported to be one of few wooden lines still in use. The construction of the pipe was similar to that of an oak barrel, that is, individual tongue and groove dimensional lumber held together by steel banding.
Over the years, the pipe developed severe leaks that significantly increased the volume of fresh water needed to maintain proper flow for process cooling. Excavation and replacement of the pipe, which runs beneath a number of the buildings throughout the plant, was not feasible due to the economic and logistical constraints such as performing selective demolition on structures to gain access to the pipe trench. Further, the plant could not be shut down for the length of time needed to excavate and replace the pipe.
Ultimately, the decision was made to reline the pipe using CIPP over a five-day period during a major maintenance shutdown. The plant rarely has a shutdown where the water line could be out of service for the rehabilitation process. As-built drawings of the pipe were not complete, but generally indicated that 410 ft of pipe needed to be relined and that the pipe had four 45-degree bends at various intervals along its length. Based on this limited information and the lack of video inspection data from the pipe, it was unclear if the pipe could be rehabilitated in the five-day window that was available.
The installation crew faced many challenges on this project. The first was that the installation/inversion point for the host pipe was inside one of the buildings and located 130 ft from the installation equipment that included a boiler and refrigerated “reefer” semi trailer, used to store the prepared, resin-impregnated liner.
Furthermore, the inversion equipment had to be set up 10 ft above the existing floor to generate sufficient “head,” or water pressure, to invert the liner inside the host pipe. There was only one place in the building that could accommodate the necessary equipment height, but this required Veit crews to remove a steel staircase and overhead catwalk to make room for the equipment.
In addition to the vertical distance limitation, the horizontal distance from the reefer trailer to the installation/inversion point posed another challenge. The distance from the trailer to the installation/inversion location would expose 130 ft of the impregnated liner to ambient temperatures, which could potentially activate the catalysts in the liner resin, causing the liner to become hard prior to placement in the host pipe.
The final, but no less challenging, aspect of the project, would be navigating the liner through the 45-degree turns in the host pipe.
To counter the first problem of the distance between the reefer trailer and the installation/inversion point, Veit used small, wheeled carts to move the impregnated liner. Bagged ice was placed on top of the liner to keep the catalysts from activating the resins, but liner installation speed would prove to be the most critical success factor in preventing the liner from hardening prematurely.
The challenge of inverting the liner through 45-degree turns became a bit more complicated than was previously anticipated. Upon closer inspection, it was revealed that the pipe had four 90-degree turns and one 45-degree turn along its length, not just the 45-degree turns as initially indicated. When inverting the liner through the 90-degree turns within the host pipe, crews needed to ensure that the liner would not “deadhead” or become stuck on the host pipe wall.
Veit crews overcame this challenge by utilizing their proprietary process of turning liners through high-angled turns in host pipes. This is done remotely through the inversion manhole and does not compromise liner wall thickness at the turn area. Based on its performance on similar projects, Veit utilized liner supplied by Applied Felts and resin supplied by Interplastic Corp. for this application.
Despite the challenges crews faced at the site, the work was completed on budget and in a fraction of the time originally estimated. Veit completed the project in just over two days, well ahead of the five-day schedule originally allocated.
Rehabilitating the water line using CIPP technology resulted in the plant only being down for two days instead of the 30-plus days it would have taken to replace the water line using traditional excavation. Project pre-planning and innovation, combined with Veit’s high capacity hot water curing equipment, contributed to success of the project.
Chuck Geisler is director of sales and marketing with Veit, a Rogers, Minn.-based specialty contractor.