Abstract: An improvement to the sealing ring of U.S. Pat. No. 4,085,951 is disclosed, wherein the sealing ring is of a special design including an in situ sealing flange generating corner, and the stepped thread pin and box members have been modified in the shoulder areas between the thread sections thereof to provide a pressure transmitting area for transmitting torque to the ring, and an undercut area to provide room for formation of the in situ sealing flange which extends beyond the faces of the improved ring.With the improved design, the sealing ring is capable of retaining hot gases or liquids with a pressure differential across the sealed joint exceeding the yield pressure of the rubber or plastic of which the ring is made, in at least a given direction.