Abstract: Means to form a coupling between lengths of pipe, a male component having at least one annular rib on the outer surface of the male component and a female component having at least one annular groove corresponding in number to the number of annular ribs, one for each rib, to accommodate the at least one annular rib when the coupling is made to permit free rotation of the at least one annular rib in the at least annular groove when the coupling is made, and means to facilitate the entry of the rib into the groove, said means comprising at least one groove or slot corresponding in number to the number of annular ribs disposed at an angle between about 65.degree. and about 80.degree. to the longitudinal axis intersecting the at least one annular groove.