DE2744739

A coupling for sealing two tubes together in end-to-end sealing engagement, comprises an outer tubular sleeve having an interior bore with a plurality of radially extending grooves therein at spaced axial locations and an inner tubular seal arranged within the outer tubular sleeve and having an exterior wall with radially outwardly extending ribs which engage into the respective grooves. The seal has an interior bore with an entrance diameter at each end at least as large as the tubes to be joined or larger so as to have an inwardly tapered entrance. The seal includes a bore wall defining a compression flange with an inwardly, gradually tapering wall adjacent each entrance which tapers inwardly in an axial direction for diameters substantially smaller than the tube. The compression flange also includes an opposite steeply tapering wall which extends in an axial opposite direction to the gradually tapering wall. A lip of less axial length than the flange is spaced axially inwardly of the flange on the seal member and has a minimum diameter substantially the same as the minimum diameter of the flange. The seal member has a first portion between the flange and the lip which accommodates the deflection of the flange and a second portion inwardly of the lip toward the center of the seal which accommodates a deflection of the lip. The flange is sized so that it will be deflected by the tubular member up to a point at which it engages the rear part of the lip which is also deflected into an undercut part of the seal member which has a diameter less than the exterior diameter of the tube to be joined. The seal also advantageously includes a centering flange at the center thereof which has a diameter much smaller than the diameters of the tubes to be joined so that they do not come into engagement.