CIPP Lining Extends Application to Gas Ventilation and Instrumentation Pipelines
The cured-in-place pipe (CIPP) lining process is perhaps best known for itsapplication in sewer pipes. Due to the work of the PIM Corp. of New Jersey forthe Consolidated Edison Co. of New York Inc. (Con Edison), the CIPP process isextending its application into lining ventilation and instrumentation pipelinecasings. The process is saving The City of New York and Westchester County fromthe disruption associated with open-cut excavation work, while also creatingsubstantial cost-savings for Con Edison.
Proper ventilation ofunderground concrete gas regulation structures is an important component to thesmooth operation of the gas distribution system, so when Con Edisons gasengineering and pressure control departments identified that many of themetallic ventilation lines were failing due to external corrosion and would needto be rehabilitated they contacted research and development for asolution.
Upon investigation, it was clear that age and I/I (inflow andinfiltration) were causing the gas regulation vaults and ventilation pipes tohave limited functionality, partially fill with water and debris, andthreatening proper ventilation because of obstructions throughout theunderground structures. The pressure control department had tried CIPP reliningin the past to address the same issues, but due to the thickness of the linersused it was extremely difficult to navigate the multiple bends in theconduit.
R&D discussed the problem with PIM Corp. Having knowledge ofthe advantages of a CIPP rehabilitation system called MaxLiner, PIM suggestedextending the MaxLiner application beyond sewer pipes and into the buried steelventilation conduits. PIM president Bob Torielli was familiar with the MaxLinersystem and understood its many benefits, specialized compact equipment, and,most important, its flexible, high-strength liners that are able to negotiatemultiple 45- and 90-degree bends to create a new pipeline within the old steellines.
In support of this innovative application, MaxLiner representatives went withPIM to propose the solution to the Con Edisons gas engineering and pressurecontrol departments. To ensure the jobs success, MaxLiner custom-designed itsproducts for this application and provided two onsite technicians to ensureproper training and implementation of this technology. Both departments agreedthat the MaxLiner system would be an innovative solution to handle the reliningof the ventilation pipes in the regulator manholes.
Before the liningprocess could begin, PIM crews needed to clean and prepare the old carbon steelcasings. They used custom-built, ultra-high pressure water blasting and cuttingequipment that enabled crews to pump 20,000 psi of water through the pipes andaround the multiple 90-degree bends to thoroughly clean the 2-, 4- and 6-in.pipelines and extract any of the old liners that had failed over theyears.
After the pipes were cleaned and free of the old liners, PIM was readyto line using the MaxLiner system.
The team chose to use theMaxLiner System because of its compact equipment and custom-made liners. Theteam selected Max WovoLiner with a 4-in. diameter, MaxLiners most flexibleliner, perfect for navigating 90-degree bends and strong enough to withstand theimpact of heavy traffic and I/I. The 4-in. diameter liner proved to be extremelyversatile as it was able to expand and contract, enabling it to line the 4-in.,6-in. and combination 4-in./6-in. pipes. For the smaller 2-in. diameter pipes,the team selected MaxLiners Intec Liner.
The team combined MaxPox 15resin with MaxPox 16 hardener, which work together to form the epoxy that, whencombined with the liner, constitutes the new pipe within a pipe. The MaxPox 16hardener was selected because it has a faster curing time by design, allowingthe team to have the pipes back in service within four to six hours. Thisenabled Con Edison to return the gas pressure regulation vaults to service veryquickly, rather than having to keep them out of service for longperiods.
The epoxy is environmentally friendly and does not containstyrene whereas vinyl and polyester resins contain about 40 percent styrene,making epoxy resin a better choice for an air ventilation pipe.
Within a 45-day period, PIMwas able to rehabilitate more than 30 gas regulation vaults and ninety 2-, 4-and 6-in. vent conduits with varying lengths from 10 to 50 ft. These previouslyfaulty pipes prevented fresh air from entering into the underground structures,causing severe damage to interior gas regulation piping and equipment. Therehabilitation process is continuing and the rehabilitation of the interiorpiping and manhole structures by cleaning and epoxy coating has also been addedto the program, and is under evaluation for long term viability in thesubterranean environment.
We had tried CIPP lining methods in the past,but before MaxLiner we could not find a liner that could negotiate the multiplebends the old liners would bunch at the elbows and cut off critical air flow tothe structure, said Len Toscano, operations manager-gas operations for ConEdison. The MaxLiner system with its compact equipment and its flexible liningproduct has proven to be a winner in this new application. Con Edison is pleasedwith the work of PIM and its ability to deploy this innovative solution.