Abstract: An annular facing is machined in an inside surface of the spherical wall around the periphery of a zone where the wall has a bore for securing the tube passing therethrough. A first welding material is deposited in the facing, and the bore is made by drilling through a portion of the spherical wall that is surrounded by the facing. The tube is engaged tightly in the bore, and a second welding material is deposited in the facing at the periphery of the tube in order to weld the tube to the first welding material. At least one of the operations of depositing the first and second welding materials in the facing is performed automatically by causing a welding torch to turn around the axis of the bore while moving the torch in a direction that is parallel to the axis of the bore and while causing it to pivot about an axis that is orthogonal to the axis of the bore while rotation is taking place.

Abstract: An annular facing is machined in an inside surface of the spherical wall around the periphery of a zone where the wall has a bore for securing the tube passing therethrough. A first welding material is deposited in the facing, and the bore is made by drilling through a portion of the spherical wall that is surrounded by the facing. The tube is engaged tightly in the bore, and a second welding material is deposited in the facing at the periphery of the tube in order to weld the tube to the first welding material. At least one of the operations of depositing the first and second welding materials in the facing is performed automatically by causing a welding torch to turn around the axis of the bore while moving the torch in a direction that is parallel to the axis of the bore and while causing it to pivot about an axis that is orthogonal to the axis of the bore while rotation is taking place.

Abstract: In order to prestress a tube (4) of a heat exchanger in tension in the axial direction, with precise tailoring of the prestress, at least one of the end parts (4a, 4b) of the tube (4) is expanded diametrally using a hydraulic pressure while the tube (4) is fixed at its ends in the tube plates (3a, 3b). The value of the prestress in each of the tubes (4) of the heat exchanger is tailored by altering the initial radial clearance between the external surface of the end part (4a, 4b) of the tube (4) and the internal surface of the hole (5) passing through the tube plate (3a, 3b) in which hole the end part (4a, 4b) of the tube (4) is engaged before diametrally expanding the end part. The end part (4a, 4b) of the tube which runs substantially over the entire length of the hole (5) passing through the tube plate (3a, 3b) is hydraulically diametrally expanded.