Sealing ring for pipe coupling

Claim 1

In a coupling comprising a first annular coupling member having a face portion extending perpendicular to the longitudinal axis of the coupling, a second annular coupling member having a face portion extending perpendicular to the longitudinal axis of the coupling making contact with the first coupling member along an interface formed by said respective faces perpendicular to the longitudinal axis of the coupling, and a U-shaped sealing ring made of elastomeric material disposed in sealing relationship between said coupling members in such a way that it offers no resistance to fluid passing through the coupling, the improvement comprising an annular recess in said first coupling member face intermediate the ends thereof which retains and is filled by one limb and a middle portion of said sealing ring in sealing relationship therewith, an annular projection formed on said first coupling member face extending within the bight portion of said sealing ring, said other limb of the sealing ring having an initially concave sealing surface which is deformed into engagement with a flat surface on the face of the second coupling member so that the inner and outer rims of said concave surface are biased into firm sealing engagement with said flat surface to oppose any leakage of fluid under pressure along the interface between the first and second coupling members.