Abstract: A gas meter riser for conducting gas from an underground source of supply, such as a gas main, to a point of delivery above ground level, such as a meter or the like. The gas riser comprises a substantially totally plastic gas conduit formed by plastic tubing secured at one of its ends to an underground plastic service line. The tubing is surrounded by a protective and supporting metal pipe casing which extends partially above ground level and partially below ground level. The metal pipe casing, its lower end adapted to be disposed below ground level, is moisture sealed about the plastic tubing. The upper ends of the plastic tubing and metal pipe casing are adjacent and structurally secured to each other in sealed fashion by a plastic transition adapter and a cooperating metal fitting. The adapter, at its lower end, is secured to the upper end of the plastic tubing, and, at its periphery, sealingly engages the metal fitting which, in turn, is secured to the upper end of the metal pipe casing.