Abstract: A transverse cut (18, 19) is made on a heat exchanger tube (4) to be replaced in the vicinity of its connectors (14, 15), at each end. A cut (19') is made in the frustoconical zone (16') of connection of the tube (4) to the second connector (15). The cutting operations are effected from inside the tube (4) and through one of the tube plates (2, 3). The tube (4) to be replaced is extracted from the heat exchanger through the interior of the second connector (15) and the corresponding opening (13) in the second tube plate (3). A replacement tube is introduced into the heat exchanger through the opening (13) in the second tube plate (3) until a first end of the tube engaged in the heat exchanger reaches the level of the cut zone (18) of the first connector (14). The first end of the tube is welded on the first connector (14).

Abstract: The invention concerns a thermal transfer layer with high transfer coefficient between two materials which can have different expansion coefficients. The thermal transfer layer comprises expanded graphite inserted between the materials which are selected from among carbonaceous materials, ceramics and metals or metal alloys. The expanded graphite is either inserted in the form of a rolled or compressed sheet, or is compressed in situ. The invention also concerns a device for the cooling of a structure subjected to intense, continuous, intermittent or pulsating heat flux, by means of fluid circulation tubes placed in the passages in the structure. A flexible material which is a good heat conductor in a compressed state, such as expanded graphite, is placed between the structure to be cooled and each tube.