Abstract: A disassembleable core heat exchanger is disclosed. The heat exchanger includes an elongated housing which defines a first passageway. A first end portion defines a second passageway which registers with the "passageway". A first tube retaining plate is metallurgically sealed within the first opening and a plurality of core tubes extend through and are sealingly engaged to the first tube retaining plate. The core tubes slidably extend through the passageway to a second tube retaining plate which is disposed remote from the first tube retaining plate. A first seal is disposed between the first end portion and the elongated housing. A second seal is disposed between a second end portion and the passageway. The second end portion cooperates with the second tube retaining plate. The two end portions are adjustably clamped relative each other to seal the second tube retaining plate relative to the elongated housing.

Abstract: A method of making the heat exchanger is also disclosed which includes a ring which is slipped over the periphery of the second tube retaining plate and brazed thereto and a gasket which is slipped over the tube core to form a seal between the first end portion and the elongated housing. An O-ring is slipped over the ring after the replacement of the core tubes within the housing. The O-ring seal forms a seal between the ring and the housing when the two end portions are moved towards each other by adjustable tie rods. An alternative embodiment of the invention includes an annular ledge defined by a ring or seal seat encircling the tube retaining plate and an annular shoulder extending between a bore and a counterbore of the elongated housing. The ledge and the shoulder are coplanar such that an O-ring pressed against a washer seated against the ledge and shoulder seals the annular groove between the tube retaining plate and the housing.