Abstract: The bearing unit of the sealing device of the thermocouple column (40) has an end part (23) in which is provided the bearing area (48) for the thermocouple column (40). This end part has two successive sections in the axial direction, a first section (25) being fastened to the outer end of the follower and a second section (26) being superposed on the first. The first section (25) has a peripheral annular throat (28) and at least three openings (29) traversing the sections (25) in an axial direction so as to open into the peripheral throat (28). The second section has openings (32) in the extension of the openings (29) of the first section. A mounting piece (30) consisting of two half-rings is introduced into the peripheral throat (28) and has tapped openings (35) in the extension of the openings (29, 32) of the first and of the second sections into which screws (36) are introduced and screws into the tapped openings ( 35). A sealing strip (31) is placed between the two sections (25, 26).