Abstract: A coupling sleeve for joining the ends of two conduits. One end is threaded, the other is unthreaded. The conduit has a female thread which engages the threaded end. The unthreaded end has a terminal portion of reduced external diameter running to an inwardly displaced groove in which a locking ring is disposed. The end of the coupling sleeve which engages the unthreaded conduit end has a recess in which the locking ring is axially slidable and a flange that engages a full diameter external section of the unthreaded end. The recess is long enough to permit the coupling sleeve to be fully received on the unthreaded conduit end when the female thread is disengaged from the threaded end of the conduit.

Abstract: A coupling sleeve for joining the ends of two conduits. One end is threaded, the other is unthreaded. The coupling sleeve has a female thread which engages the threaded end. The unthreaded end has a terminal portion of reduced external diameter running to an inwardly displaced groove in which a locking ring is disposed. The end of the coupling sleeve which engages the unthreaded conduit end has a recess in which the locking ring is axially slidable and a flange that engages a full diameter external section of the unthreaded end. The recess is long enough to permit the coupling sleeve to be fully received on the unthreaded conduit end when the female thread is disengaged from the threaded end of the conduit.

Abstract: Each section of a conduit with a constant diameter axial passageway has male pipe threads formed on its outer wall surface at one end. A coupling sleeve is retained captively on the other end of the conduit section by a resilient lock ring means positioned partially in an annular lock ring groove disposed on the outer surface of the conduit section axially inwardly of the end face of the conduit section, i.e. -- in a direction along the conduit section away from this end face, and partially in an annular lock ring groove disposed on the inner surface of the coupling sleeve. The lock ring means spans the two annular lock ring grooves to prevent the coupling sleeve from being pulled axially outwardly off the conduit section.

Abstract: Each section of a conduit has a male pipe thread 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 with a decreased axial passageway through the reduced diameter length. A sloping annulus is formed between the length of decreased outside diameter and the remainder at the conduit section. The other end is flared and has a flat end face substantially perpendicular to the longitudinal axis of the conduit section. A coupling sleeve has an annular flange at its axially inward end which defines a central opening such that the coupling sleeve may slide freely to a limited extent over the length of decreased diameter of the other end of the conduit section. The axially outward end of the coupling sleeve has female machine threads formed thereon. Intermediate the inner surface of the flange and the threaded portion is a sloped shoulder.

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.