Abstract: A pipe coupling particularly for use in connecting plastics piping having an appreciable coefficient of thermal expansion and required to withstand appreciable pressures, and avoiding the need for an internal groove for housing a sealing ring in the coupling which would require machining or a collapsible core, comprises a socket portion with two internal radial enlargements, an end cap having an outer portion secured on the outside of the socket portion and an inner portion with an internal diameter substantially equal to that of the initial bore, a washer adjacent a shoulder at the junction between the enlargements and having an internal diameter substantially equal to that of the bore, a resilient sealing ring housed between the inner portion of the end cap and the washer, and a toggle ring slidable along the first enlargement and having an aperture smaller in diameter than that of the bore, so that a pipe-end inserted into the socket makes sealing contact with the sealing ring and is gripped by the toggle