A hub clamp will be used to connect two conduits together in end-to-end relationship. Each conduit has a pair of generally parallel load shoulders that extend around the conduit and are axially spaced from each other. The clamp has two sets of load shoulders, one for engaging each set of load shoulders on each end of the conduit. The clamp is in two halves, and when bolted together, draws the ends of the conduits toward each other. Each load shoulder is separated by a flank. The two flanks of the mating load shoulders are separated by a gap when fully made up. The first load shoulder of each conduit has multiple angled sections. The lead section is at a greater angle than the load section relative to a plane perpendicular to the longitudinal axis of the conduit. The clamp will be mounted releasably to an upper conduit so that it can slide inward and outward, for vertical conduit applications.