F1867-98 Standard Practice for Installation of Folded Formed Poly Vinyl Chloride PVC Pipe Type A for Existing Sewer and Conduit Rehabilitation This practice covers the procedures for the rehabilitation of sewer lines and conduits 4 in 102 mm to 18 in 457 mm in diameter by the insertion of a folded formed PVC pipe that is heated pressurized and expanded to conform to the wall of the original conduit forming a new structural pipe-within-a-pipe This rehabilitation process can be used in a variety of gravity applications such as sanitary sewers storm sewers and process piping