What Is Cured-In-Place Pipe?

Learn what cured-in-place pipe is and how it can save your sewer system.


A cured-in-place pipe (CIPP) is one of several trenchless rehabilitation methods used to repair existing pipelines. CIPP is a jointless, seamless, pipe-within-a-pipe with the capability to rehabilitate pipes ranging in diameter from 0.1–2.8 meter (4"–110"). As one of the most widely used rehabilitation methods CIPP has application in water, sewer, gas, and chemical pipelines.

A resin-saturated felt tube made of polyester, fibreglass cloth or a number of other materials suitable for resin impregnation, is inverted or pulled into a damaged pipe. It is usually done from the upstream access point (manhole or excavation). It is possible to invert the liner upstream (e.g. from the downstream access point) but this carries greater risk. It is possible to install a liner from the downstream access point, upstream to a blind end however this carried the highest risk of all the CIPP installation methods. Little to no digging is involved in this trenchless process, making for a potentially more cost-effective and less disruptive method than traditional "dig and replace" pipe repair methods. The liner can be inverted using water or air pressure. The pressure required for inversion can be generated using pressure vessels, scaffolds or a "Chip unit". Hot water, UV light, ambient cured or steam is used to cure the resin and form a tight-fitting, jointless and corrosion-resistant replacement pipe. Service laterals are restored internally with robotically controlled cutting devices in the larger diameter pipe. Smaller diameters (100mm)can be opened remotely however they are often reinstated by excavation. These can be sealed with additional seals into the lateral connection (Lateral Junction Repair)or T-Liner. The resin used is typically Polyester. Since all resins shrink and it is impossible to bond to a sewer that has Fats, Oils, and Grease an annular space exists between the new CIPP liner and the host pipe. The annular space exists in all installations just some are larger than others. The most effective way to prevent water from tracking in the annular space and entering back into the waste stream is through gasket sealing technology. Gaskets made from water swelling material (hydrophilic) can be placed at the ends of the host pipe and at the lateral connections. ASTM F2561 is the current industry standard for main to lateral connection lining by cured in place method. The rehabilitated pipe is then inspected by closed-circuit television (CCTV). CIPP is considered a trenchless technology.

As a trenchless technology, CIPP does not require excavation to rehabilitate a pipeline that is either leaking or structurally unsound. Depending upon design considerations an excavation may be made, but the liner is often installed through a manhole or other existing access point. Anything larger than 60" must be excavated in order to install. Liner is installed as it is wet out on site in these instances. In the case of sewer lines, lateral connections are also restored without excavation via a remote controlled device that drills a hole in the liner at the point of the lateral connection. If larger than 24" and it is safe to do so someone will reinstate laterals by hand. CIPP has a smooth interior and no joints. While CIPP can repair a pipe with bends, special design considerations must be taken into account to prevent wrinkling and stretching. CIPP can effectively reduce infiltration and leaks in pipeline systems without digging.

Eric Wood was born in South Yorkshire England. Attending Harper Adams Agricultural College- Wood became an agricultural engineer with a talent for invention. This talent was the motivation that created an entire industry.

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