Abstract: A method of lining a main fluid conduit 1 having a branch conduit 2 and apparatus for use in the main conduit includes a carrier 7 which is longitudinally displacable in the conduit 1. A portion 9 of the carrier is rotatable above a longitudinal axis and carries a scissors-type extendible linkage 10 having a platform 11. By rotation of the portion 9, displacement of the carrier 7, and extension of the linkage 10, service structure on the platform 11 can be maneuvered to be located in the branch conduit 2. The service structur=e may be a water jet cutter or a locating member 15 having a chamber which is expandible by fluid pressure to engage the sides of the conduit 2 and be retained therein. The locating member 15 includes a metallic part which a metal detector can detect through a lining which is fitted in the main conduit 1 to determine the position at which a port has to be cut in the lining to coincide with the branch conduit 2.