A process that uses friction stir welding to connect a tube, for example a thin gauge tube having a wall thickness of about 2.54 mm (0.100 inch) or less, to another element, such as a tube sheet of a heat exchanger. The process employs a tubular anvil that is installed into the end of the tube and which, in one embodiment, can provide material during the friction stir welding process. After the weld is complete, the weld zone between the tubular anvil and the tube is machined away and the anvil tube removed.

An anti-freezing pipe having a built-in tube and a high-efficiency heat exchanger using the same, includes a heat transfer pipe made of metal and configured to allow a fluid to move therethrough and a hollow tube located and supported in the heat transfer pipe. The tube has a sealed space defined therein by sealants fitted into both end portions thereof and is provided on an outer diameter surface thereof with a wing formed in a spiral shape, and the heat transfer pipe is 10 provided at an end portion thereof with a stopper to prevent escape of the tube therefrom due to the flow of fluid.

A tube transition fitting includes a body having a scalloped end having a raised portion and a depressed portion connected by a continuously sloping transition portion. The fitting is formed having a first wall thickness and a second wall thickness. A tube seat is formed on a surface connected to the body, the surface being adjacent a transition from the first wall thickness to the second wall thickness. A tube transition assembly includes a header portion, the tube transition fitting, and a heat exchange tube, each being connected using one or more simplified and/or heat-optimized connections.

An apparatus (e.g., tube sheet) includes a plate piece, a sleeve piece, and a tube piece. The plate piece defines a hole. The sleeve piece has first and second ends; the second end is shaped to fit through the hole for attachment of the sleeve piece to the plate piece. The tube piece also has first and second ends. Inner and outer cross-sectional geometries of the tube piece and the sleeve piece (e.g., in the case of round tubes, inner and outer diameters) are shaped for the first end of the tube piece to fit in the first end of the sleeve piece and to form a continuous interior fluid flow path from the second end of the tube piece through the plate piece when the sleeve piece is disposed in the hole and attached to the plate piece and the tube piece is disposed in the sleeve piece.

A tube transition fitting is formed having a first end, a second end, a head, a body, a weld area, and a first wall thickness and second wall thickness. A tube seat is formed on a surface connected to the body, the surface being adjacent a transition from the first wall thickness to the second wall thickness. A tube transition assembly includes a header portion, the tube transition fitting, and a heat exchange tube, each being connected using one or more simplified and/or heat-optimized connections.

This heat exchanger (100) includes a core portion (1), a header portion (2), and an intermediate member (3), and the curvature radius of a corner (31a to 31d) of the intermediate member is configured to be smaller than the curvature radius at a header portion side.

A process of producing shell and tube heat exchangers where the ends of the tubes are secured to a tube sheet while reacting applied FSW forces without introducing a crevice or local deformation near the ends of the tubes. In particular, an interference fit is used to lock the ends of the tubes into the tube sheet without flaring or expanding the tube ends. A FSW process is then used to weld the ends of the tubes to the tube sheet.

A process of producing shell and tube heat exchangers where the ends of the tubes are secured to a tube sheet while reacting applied FSW forces without introducing a crevice or local deformation near the ends of the tubes. In particular, an interference fit is used to lock the ends of the tubes into the tube sheet without flaring or expanding the tube ends. A FSW process is then used to weld the ends of the tubes to the tube sheet.

A process of producing shell and tube heat exchangers where the ends of the tubes are secured to a tube sheet while reacting applied FSW forces without introducing a crevice or local deformation near the ends of the tubes. In particular, an interference fit is used to lock the ends of the tubes into the tube sheet without flaring or expanding the tube ends. A FSW process is then used to weld the ends of the tubes to the tube sheet.

This heat exchanger (100) includes a core portion (1), a header portion (2), and an intermediate member (3), and the curvature radius of a corner (31a to 31d) of the intermediate member is configured to be smaller than the curvature radius at a header portion side.