Pipe joint for an intermediate metal conduit

Abstract

Each section of an intermediate metal conduit with a constant diameter axial passageway has male pipe threads formed on its outer wall surface at one end. The other end of each conduit section has a short length of decreased outside diameter extending axially inwardly from the flat end face of the section, to form an external annular stop shoulder. A coupling sleeve has a pair of annular flanges which define central openings in mutual axial alignment but of different diameters such that the coupling sleeve may slide freely to a limited extent over the full external diameter of said other end of the conduit section. The coupling sleeve is retained captively on this other end by a resilent constrictable lock ring positioned in an annular lock ring groove disposed axially inwardly of the stop shoulder. When the coupling ring is unstressed, it protrudes, in part, radially outwardly of the groove and is in the path of movement of one of the flanges. The coupling sleeve can be retracted, i.e., moved axially inwardly, until the other flange, this being female threaded, abuts the stop shoulder. The axial extent of the short length of decreased outside diameter is such that when said other flange abuts the stop shoulder the end face of the coupling ring does not project beyond, e.g., is flush with, the associated end face of the conduit section. Assembly of conduit sections can be achieved without having to rotate either section. The end face of the threaded end of a first conduit section is butted against the end face of a reduced outside diameter end of a second conduit section. The coupling sleeve is screwed on to the threaded end until the one flange presses against the lock ring, causing the flat end juxtaposed faces of the two conduit sections to be pressed together with considerable force thereby forming a tight joint. Additional sealing means may be provided to ensure that the joint will be leak-proof. To disassemble previously assembled sections, consecutive coupling sleeves are backed off the threaded ends of adjacent conduit sections so that the end faces of the coupling sleeves are flush with the end faces of the associated conduit sections, permitting a section to be moved transversely away from a run of conduit without relative longitudinal displacement of adjacent conduit sections.