A cured-in-place pipe (CIPP) is a trenchless rehabilitation method used to repair existing pipelines. It is a jointless, seamless pipe lining within an existing pipe. As one of the most widely used rehabilitation methods, CIPP has applications in sewer, water, gas, chemical and district heating pipelines ranging in diameter from 0.1 to 2.8 meters (2–110 inches).
The process of CIPP involves inserting and running a felt lining into a preexisting pipe that is the subject of repair. Resin within the liner is then exposed to a curing element to harden it and make it attach to the inner walls of the pipe. Once fully cured, the lining now acts as a new pipeline.