Ultraviolet light cures the UV material, while heat delivered via steam or hot water inside a calibration tube, similar to a balloon, will cure the material used in the drum and cannon. The calibration tube, or cal tube, is place inside the material inside the existing sewer line.
Air and water pressure inflates the cal tube pressing the liner material tightly against the sewer line, giving the material the same shape and curvature of the existing line.