Flange joint with welded lip seal

The invention relates to a flange joint (2) with a welded lip seal (34) on a pressure vessel or the like, the welded lip seal having a diaphragm tube (36) which extends in the interior of the vessel, along the parting line (42) of the flange joint, is cut open longitudinally and the two edges (38, 40) of which formed in this way are connected in a sealing manner- at least one of them by means of a welded joint - to the two vessel components connected to one another by the flange joint. It is characterised in that a flat edge (40) of the diaphragm tube (36) projects to the outside through the gap (42) and is there welded to the relevant second vessel component. The internal arrangement of the diaphragm tube (36) makes it possible to arrange the flange bolts or the like close to the wall (16, 18) of the vessel, this being a desirable feature, while the externally located weld (46) makes it unnecessary to have access to the interior of the vessel in order to produce the weld or undo it. A suitable welding or separating device can furthermore be guided on one of the flanges (10).