Pipe relining is a common trenchless pipe repair procedure. It's appropriate for pipes that haven't been broken up by time, nature (tree roots are one example) or accidents. It's one way to prolong the useful life of a sewer or water system without mounting a full pipe replacement program. You might think of it as wrapping an adhesive bandage around a cut on your finger -- except the pipe's bandage is inside the pipe!

How Pipe Relining Works

During a pipe relining program, the trenchless repair team inserts a flexible tube (it's almost collapsable and its outside is coated with an adhesive resin) into a damaged pipe, usually from a manhole.

They maneuver the flexible tube into position so that it extends past the damaged area of the water or sewer pipe. Then the magic happens.

The repair crew blows a blast of compressed air into the tube, and the tube inflates evenly within the damaged pipe. As it inflates, the adhesive resin on the tube's exterior makes contact with and grips the interior of the damaged pipe, covering the damaged area and sealing itself securely to the pipe. It completely covers the damaged area from the inside.

Over a short period of time, the adhesive resin cures and the repair is complete. Sometimes, it's necessary to blow hot air into the tube to cure the resin. A specialized heater can be lowered into the manhole through which the tube was inserted.

Cured-In-Place Pipe

Because the liner's resin curing process occurs on-site, the tube is also called "cured-in-place pipe," or CIPP.

Relining costs less because it doesn't involve trenching to remove the pipes from the ground and because it's trenchless, it's less disruptive to surface activities.

Because the procedures are well-established, the materials are time-tested and the work is performed through the manhole nearest the damaged area, it's like very precise, minimally invasive surgery: it's very effective and less disruptive than the alternative.

Pipe Relining or Pipe Bursting?

Pipe relining and pipe bursting are both trenchless procedures. As previously stated, pipe relining is a method of patching a pipe that's damaged but doesn't require replacement.

Pipe bursting, however, is a replacement method. A special, oversized bit is forced into the pipe that's damaged beyond repair. The oversized bit tows the new, replacement pipe in behind it. The damaged pipe breaks apart as the oversized bit passes and its pieces are forced into the earth around it, as the new pipe is pulled into place. This process is known as fragmentation.