Abstract: A groove is milled along a predetermined line using a cutter (2) mounted at the end of a rotary shaft (3) which is displaced under computer control (A) via a control interface (B) in such a manner as to ensure that its axis X.sub.4 remains constantly substantially perpendicular to the wall of the tube and that the depth to which the cutter penetrates into the thickness of the wall is under constant control.

Abstract: The invention relates to a device for sealing an opening (7) defined by an edge (6), comprising a sealing element (2, 102), the dimensions of which are at least equal to those of the opening (7), means for securing the said sealing element opposite the opening, and means for ensuring fluid-tightness between the sealing element (2, 102) and the edge (6). The means for ensuring tightness between the sealing element (2, 102) and the edge (6) consists of a flexible membrane (8), means for fixing the circumference of this membrane to the sealing element (2, 102) so as to define a volume (16) between the membrane (8) and the sealing element (2, 102), and a communication hole (18, 32) provided in the sealing element so as to connect the volume (16) to a source of pressurized fluid.