Abstract: In a hydraulic method, tubes (3) of an heat exchanger are rolled in in tube plates (1), and rounded tube inlet pieces are formed from the same tube (3) by means of the same device in the same work operation. For this purpose, the tubes (3) are inserted into the bores (2) of a tube plate (1) and cut off with an excess length. The tube (3) is widened by means of a widening machine over the entire depth of the bore (2), so that the tube (3) adheres to the inner wall of the bore (2). At the same time, the projecting tube end (10) is pressed on the mandrel (4) of the widening machine in the direction of the tube plate (1) by means of a further hydraulic shaping device (11) with a swept-back shape (12) until the tube end (10) achieves a trumpet shape. The advantage of the method resides in shortening the operating time with a device which executes both widening and formation of the tube inlet piece hydraulically.

Abstract: A convective countercurrent heat exchanger comprises a nest of pipes (36) which is arranged in a cylindrical shell (35) and is equipped with ribbed pipes (37). The pipes through which a liquid flows are connected to a collector (33, 34). The shell is provided with a gas-inlet connection piece (31) and a gas-outlet connection piece (32). The nest of pipes (36), which is composed of a plurality of layered pipes, is mounted in a rectangular case (40). The pipes are provided in their straight parts (37) with welded-on ribs and are connected to one another by unribbed pipe bends (38). The pipe bends are accommodated in compartments (45) through which flow does not take place. The case (40) through which flow takes place opens on the outlet side (50) in a dome (51) which is delimited by the shell (35). The gas-outlet connection piece (32) is situated in the shell at that end of the annular chamber (44), enclosed by the shell and case, which is remote from the dome (51).