Heat exchanger tube base

An improved tube base (1, 2) for a bundle-type heat exchanger and an inner wall of a casing (3) of the exchanger, for cooperation with a tube bundle (4) of the exchanger;

• the tube base consisting of a poly laurin lactam material that has an elastic return capacity up to about 80%, a unit of thermal expansion coefficient of 0.8 to 1.0.times.10.sup.4 per degree Celsius at -60.degree. to +30.degree. C., and 1.0 to 1.9.times.10.sup.4 per degree Celsius at +30.degree. to +100.degree. C., which unit is higher than that of the tubes in said bundle and of said casing;
• said bundle being entirely cast at least at one end into said material in a gapless manner;
• said material also acting as sealing means (17, 18) between said tubes and the tube base, on the one hand, and the tube base and an inner wall of said casing, on the other hand;
• wherein a contour of a covering face of the tube base, which face is opposite said inner wall, is profiled to have a peripheral curved portion (16) for the formation of at least one sealing edge (17, 18) that forms part of said sealing means.