Abstract: A coupling assembly for leak proof connection of the ends of two lengths of pipe or tubing. One end of a first pipe is coupled to a coupling box which is connected to or integrally formed on the end of a second pipe. The coupling box has threads for engaging a nut for securing the coupling. The coupling box has a bore for receiving the end of the first pipe. The end of the first pipe has an outer tapered surface for engaging an inner tapered surface of the coupling box to form a metal to metal seal between the first pipe and the coupling box. The bore also contains an engager for coupling the nut to the first pipe. The engager includes a split ring which has a longitudinal slot. The split ring has internal circumferential projections or gripping teeth which are aligned with external circumferential projections or gripping teeth on the end of the first pipe.