Seal and clamp assembly for pipeline flanged connection

A seal and clamp assembly for sealing a flanged connection, said connection comprising a pair of flanges bolted together in substantially aligned and opposed relation, each flange having outward facing circumferential faces and radial faces the radial faces having a gasket positioned therebetween at the interface of the flanges, said assembly comprising:

• a pair of substantially rigid half rings for circumferentially encircling the flanges, said half rings having a lateral dimension substantially that of the flanged connection and having ends carrying means for securing the ends together to form a split ring having two breaks;
• each half ring comprising inner and outer wall portions, each half ring having its outer wall portion at one end and its inner wall portion at the other end recessed so that when the half rings are mounted to the flanges their opposed ends may assume an overlapping relationship and the overlapping ends enable the split ring to be contracted a limited amount;
• the inner wall of each half ring having laterally spaced apart side walls forming an internal channel of generally rectangular cross-section extending centrally and circumferentially thereof,
• each channel side wall at each recessed end forming a transverse shoulder having a radial end face, so that when the half rings are mounted to the flanges they provide a pair of inner, opposed and spaced apart radial end faces at each of the breaks;
• and
• a pair of flexible, resilient and annular seal elements, each seal element comprising parallel, coextensive, spaced apart side members of rectangular section and transverse end members, said seal element defining an elongate central opening, one such end member extending laterally beyond the side members to form a pair of laterally protruding lugs, each side member having an inner radial surface,
• each seal element being dimensioned to seat in the channel of a half ring so that it is closely supported by the channel's inner and side walls but protrudes inwardly therefrom, said seal element lugs being disposed to bear against the half ring's radial end faces, the inner radial surfaces of each seal element being non-constrained and open to pressure originating from the interface of the flanges,
• so that when the seal elements are positioned in the channels of the two half rings, the half rings are mounted to the flanged connection in the form of a split ring and the ring is contracted about the connection, then the seal elements are pressed against the flange's circumferential faces and seal against them, the flange interface communicates with the seal element central openings and the seal element inner radial surfaces, so that pressure originating from the flange interface acts to squeeze the side members against the flange's circumferential faces, and each lug-forming end member is squeezed by an opposing pair of inner opposed radial end faces to effect seals at the breaks.