A marine riser assembly having a first tubular member having an external surface with a plurality of first axially spaced formations, a second tubular member having an external surface with a plurality of second axially spaced formations thereon, a segmented ring in surrounding relationship to the first and second tubular members, the segmented ring having an inner surface with a plurality of formations engageable with the formations on the first and second tubular members, the engageable formations serving to urge the first and second tubular members toward each other when the segmented ring is subjected to radially inwardly directed compressive forces, a sleeve in surrounding relationship to force the engageable formations together and a seal assembly for sealing against external and internal pressure.