Pipe joint for an intermediate metal conduit

Claim 1

In combination: a. a first two ended conduit section with a circular cylindrical outer wall surface 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 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 circular cylindrical 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 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, said coupling sleeve including female thread means 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. each of said conduit sections including a length of reduced outside diameter extending axially inwardly from said flat substantially perpendicular end face at said other end of said conduit section to form a stop shoulder in said outer wall surface at said non-threaded end; e. each of said conduit sections having means providing an annular lock ring groove in said outer wall surface near and spaced axially inwardly from said stop shoulder; f. a resilient lock ring of a constrictable diameter, said lock ring in its normal unbiased condition projecting in part above said outer wall surface and being constrictable entirely into said annular lock ring groove; and g. abutment means extending radially inwardly on said coupling sleeve adapted to cooperate with said stop shoulder and said projecting part of said lock ring to permit free rotation of said coupling sleeve on said first conduit section and limited axially inward and axially outward movement of said coupling sleeve along said non-threaded end of said first conduit section, said abutment means including first and second radially inwardly extending flanges at opposite ends of said coupling sleeve, said second flange having said female thread means, said first flange defining a central opening of a diameter slightly greater than the diameter of said outer wall surface, said second flange defining a central opening smaller than the diameter of said outer wall surface but slightly greater than the diameter of said area of reduced outside diameter, said central openings being in axial alignment so that said coupling sleeve may be slipped on to said other non-threaded end of said first conduit section; h. an axially extending annular clearance formed between said first and second flanges; i. at least one of said lock ring and a cooperating surface of said first flange having camming means to constrict said lock ring into said annular lock ring groove when said coupling sleeve is moved axially inwardly on said other end of said first conduit section; j. said lock ring returning to its normal unbiased condition in said annular clearance when said first flange clears said ring; k. a surface of said first flange and said lock ring having cooperating abutment means to prevent said lock ring from being forced radially inwardly entirely into said lock ring groove; l. so that said coupling sleeve is prevented from being pulled axially outwardly from said conduit section over said lock ring as said coupling sleeve is threaded onto said externally threaded end of said second conduit section so as to force said end faces of said first and second conduit sections together; m. said area of reduced outside diameter extending axially inwardly at least the width of said second flange so that said coupling sleeve may be backed off said externally threaded end of said second conduit section after said first and second conduit sections are assembled whereby said second flange will abut said stop shoulder and said end face of said coupling sleeve will be at least flush with said flat substantially perpendicular end face of said first conduit section to permit said first conduit section to be laterally displaced from said second conduit section without longitudinal movement of either conduit section.