Best Practices For Cured-In-Place Pipe

Known as a “trenchless sewer repair” solution to broken pipelines, the cured-in-place pipe (CIPP) has been a low-maintenance savior for water utilities since the late ‘70s.

The technology was first patented by London’s Eric Wood, who called the process “insitu form” meaning “form in place.” First, a limp “pipeliner” husk is run through a roller to saturate it with resin. The pipeliner is sealed at one end and attached to a rope, then rolled into an inversion tank like a garden hose wrapped around a wheel. Air pressure is used to feed the unsealed end of the pipeliner into a broken pipe. The pipeliner is flexible enough to navigate bends and take the shape and size of the host pipe, serving as a new barrier to keep water and wastewater from leaking.

But it’d be folly to mistake low-maintenance for foolproof. There are smart ways to utilize CIPP and there are ways it can be messed up. Make sure you consider these best practices, with thanks to Underground Construction, if you’re planning a trenchless sewer line replacement or pipeline rehabilitation.

1. Let’s Roll: CIPP pipeliner can consist of polyester, glass fiber, or a combination of the two. No matter what it’s made of, success will depend on how well it has been saturated with resin. The resin is what guarantees a water-tight seal and to get it wedged into the microscopic holes in the material, a calibration roller and vacuum pump must be employed. Using your hands, a piece of pipe, or a linoleum roller against the ground can’t get the seal you’ll need.
2. Blowing Up: Possibly the most delicate portion of the CIPP installation is the inflation step. Some decide to invert the pipeliner into the broken pipe with water or pressurized air, some will manually pull the pipeliner into position, and still others will have the pipeliner fill the tube by inflating it. If a pipeliner is installed without the proper pressure it will not fit properly. The pipeliner manufacturer should provide a “minimum inversion head” to inform the user of the necessary pressure level and guarantee a smooth installation.
3. The Cure: Once the pipeliner is in place, heat or ultraviolet light must be applied to cure the resin and harden it. In the case of heat-cured resin, the system manufacturer should supply a minimum temperature guideline and the user must ensure the resin is reaching this level at as many points as necessary. For those using hot water or steam to cure the pipeliner, make sure to note that the bottom of the CIPP will receive less heat than the top.
4. Cool It Now: The ever-sensitive resin, now heated or brightened to its curing temperature, must be cooled down to a stable temperature as a final step to avoid shrinkage. Once any heat source used for curing has been removed, internal pressure can be changed and the CIPP will be ready for business.