Joint for conduit

Claim 1

In combination: a. a first two-ended conduit section having a length which equal to at least four times its outer diameter with a circular cylindrical outer wall surface of a constant diameter extending substantially the entire length of said conduit section and an axial passage of constant cross-sectional dimensions and configuration, one end of said first conduit section having external thread means thereon and a flat substantially perpendicular end face, the outside diameter of said thread means not exceeding said constant diameter, and said other end of said first conduit section being non-threaded and having a flat substantially perpendicular end face; b. a second two-ended conduit section identical to said first conduit section having a length which is equal to at least four times its outer diameter, having a circular cylindrical outer wall surface of a constant diameter extending substantially the entire length of said conduit section, said outer wall surface equal in diameter to said outer wall surface of said first conduit section and an axial passage of constant cross-sectional dimensions and configuration equal to said axial passage through said first conduit section, one end of said second conduit section having external thread means thereon with a flat substantially perpendicular end face matching and abutting said adjacent flat substantially perpendicular end face of said other non-threaded end of said first conduit section, the outside diameter of said thread means not exceeding said constant diameter, and said other end of said second conduit section being non-threaded and having a flat substantially perpendicular end face; c. a coupling sleeve having an end face and having first and second portions on opposite ends thereof, said first portion defining a central opening of a diameter slightly greater than the diameter of the entire length of said circular cylindrical outer wall surface so that said coupling sleeve may be slipped onto said first conduit section, said second portion defining a central opening of a diameter smaller than the diameter of said circular cylindrical outer wall surface and having female thread means formed therein extending from adjacent said end face and constructed and dimensioned to engage said external thread means on said one end of said second conduit section; d. means providing an annular lock ring groove having an axially inward side and axially outward side in said outer wall surface of said first conduit section, near and spaced inwardly from said end face at said other, non-threaded end; e. means providing an annular lock ring groove on the inner surface of said coupling sleeve in said first portion; and f. at least one resilient lock ring of a variable diameter received partially within each of said annular lock ring grooves in its unbiased condition, a said annular lock ring groove having a depth at least equal to the cross-sectional height of said at least one lock ring; g. at least one of said first portion of said coupling sleeve and said other end of said first conduit section provided with camming means to urge said lock ring fully into said annular lock ring groove when said coupling sleeve is first moved axially inwardly on said first conduit section, said lock ring in its unbiased condition spanning said annular lock ring grooves thereby captively holding said coupling sleeve on said first conduit section to form a coupling sleeve and conduit section unit and permitting rotation of said coupling sleeve on said first conduit section so that said coupling sleeve can be threaded onto said end of said second conduit section so as through said lock ring to force said end faces of said first and second conduit sections together; h. said central opening defined by said first portion being dimensioned to create a clearance between said first portion and said outer wall surface of said other non-threaded end of said first conduit section to thereby permit swivelling of said coupling sleeve on said non-threaded end of said first conduit section so that said female thread means on said coupling sleeve can mate with said external thread means on said other end of said second conduit section when said first and second conduit sections are not in exact axial alignment.