Patent ID: 8429819

Claim:
A method for retrofitting a U-tube heat exchanger, the method comprising: providing a U-tube heat exchanger having a shell enclosure having first, second and third chambers therein, a tube sheet separating first and second chambers from a third chamber in the shell enclosure, and 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; forming a first inward-facing conically tapered sealing surface on the shell enclosure; forming an outward-facing conically tapered sealing surface on one of the group consisting of the closure and the tube sheet; wherein the first sealing surface of the shell enclosure and the sealing surface of the closure or the tube sheet form a first gap having a wedge-shaped cross-section; providing a first tapered seal ring having an outward-facing conically tapered surface complementary to the first sealing surface of the shell enclosure and an inward-facing conically tapered surface complementary to the sealing surface of the closure or the tube sheet; positioning the first seal ring in the first gap; and coupling the closure or the tube sheet to the shell enclosure.