A high pressure sealing connection for sealing between coaxially aligned members (22, 10) which are connected by metal bolt means having a different coefficient of thermal expansion from the aligned members. The connection comprises a metallic sealing ring (40) having at its largest external diameter a curved arcuate peripheral surface 52 characterized by a center of curvature which is co-diametral with the center of the seal ring but may be of greater or lesser radius than the radius of the ring. At its inner periphery, upper and lower flanges (61, 62) extend inwardly and perpendicularly to the axis of the ring. The coaxially aligned members (22, 10) are provided with recesses defined by opposed internal frusto-conical sealing surfaces (41, 42) at their adjoining ends, each tapering inwardly from the end of the member to an annular shoulder (43, 44) in the bore of the aligned member. The frusto-conical surfaces (41, 42) are of equal taper in the range of 5 degrees to 20 degrees. Drawing the coaxially aligned members together by suitable bolt means (31) results in a compression of ring (40) and a sealing relationship between the ring and the aligned members which is enhanced by fluid pressure energization. The internal flanges (61, 62) significantly increase the elastic zone of the ring to include the flanges themselves which continue to urge the seal ring in sealing engagement with the aligned members even after high pressure or temperatures have caused a deformation of the sealing ring or the aligned members. The curved outer surface of the seal ring in conjunction with the tapered frusto-conical surfaces of the seal grooves permits the points of sealing contact to roll as the geometry changes with differential thermal expansion.