GRP lining is a hose relining method in which the inliner used is a seamless glass fibre fabric hose. GRP lining can be used to rehabilitate sewers with damage such as root penetration, deposits, socket offset, cracks and pipe fractures. Once the existing pipe has been cleaned and inspected by a camera, it is prepared for rehabilitation with milling and smoothing robots. A winch then pulls the folded inliner hose into the existing pipe through a shaft. When subjected to compressed air the inliner unfolds and applies itself to the inside wall of the existing pipe. The curing method is selected according to site conditions - using either ultraviolet light or a mixture of air and steam. Unsaturated polyester resins or vinyl ester resins are used, depending on the level of exposure to chemicals. The curing process is continuously monitored and recorded with the help of automated devices.