Abstract: What is disclosed herein deals with low to medium pressure, high temperature, all ceramic, air-to-air, indirect heat exchangers, novel ball joints; connecting slip ring collars for ceramic tubes, that are useful in such heat exchangers, systems comprising several heat exchangers or systems comprising heat exchangers that are fabricated such that they provide more efficient heat exchangers than has been possible heretofore.

Abstract: A plate-fin type of heat exchanger (400) facilitates exchange of heat between two process streams (S1, S2) e.g. high pressure methane and seawater. It comprises a matrix (M) of heat exchange plate elements (200') arranged side-by-side, flow passages (401) for the seawater process stream (S2) being defined between adjacent plate elements. The plate elements (200') are a high-integrity diffusion bonded sandwich construction comprising two outer sheets (101, 103--FIG. 3) and a superplastically expanded core sheet structure (102--FIG. 3) between the two outer sheets. The sandwich construction provides flow passages (117') for the methane process stream. Adjacent plate elements (200') are held in position relative to each other by serrated racks (403) which engage the edges of the plate elements.

Abstract: An annular seal for use in a heat exchanger connection comprising a tube and at least one annular seal, wherein the annular seal is compression seated upon the outside diameter of the tube.