Patent ID: 7854254

Claim:
An improvement in a U-tube heat exchanger, wherein the heat exchanger comprises a shell enclosure, a tube sheet separating first and second chambers from a third chamber in the shell enclosure, a closure a plurality of tubes extending through the tube sheet into the third chamber, wherein each tube has a first end in fluid communication with the first chamber and a second end in fluid communication with the second chamber, the improvement comprising a first seal between the shell enclosure and a second seal between the tube sheet and the shell enclosure; the closure wherein the first seal includes a first radially inward-facing conically tapered sealing surface on the shell enclosure, a radially outward-facing conically tapered sealing surface on the closure, and a first tapered seal ring having a radially outward-facing conically tapered surface complementary to the sealing surface of the shell enclosure and a radially inward-facing conically tapered surface complementary to the sealing surface of the closure, wherein the first sealing surface of the shell enclosure and the sealing surface of the closure form a first gap having a wedge-shaped cross-section and the conically tapered surfaces of the first seal ring form a wedge-shaped cross-section which is complementary to the first gap; wherein the second seal includes a second radially inward-facing conically tapered sealing surface on the shell enclosure, a radially outward-facing conically tapered sealing surface on the tube sheet, and a second tapered seal ring which is separate from the first tapered seal ring having a radially outward-facing conically tapered surface complementary to the second sealing surface of the shell enclosure and a radially inward-facing conically tapered surface complementary to the sealing surface of the tube sheet, wherein the second sealing surface of the shell enclosure and the sealing surface of the tube sheet form a second gap having a wedge-shaped cross-section and the conically tapered surfaces of the second seal ring form a wedge-shaped cross-section which is complementary to the second gap.