The invention concerns a sealed tank including adjacent first and second walls each comprising a corrugated sealing membrane. The sealing membranes of the first and second walls join at the level of an edge, wherein the sealing membrane of the first wall includes a first series of corrugations and a second series of corrugations intersecting at the edge, and the sealing membrane of the second wall includes a third series of corrugations intersecting at the edge. The tank further includes a corner arrangement comprising a sealing membrane that is welded in sealed manner to the sealing membrane of the first wall and to the sealing membrane of the second wall, such that the corrugations of the first series of corrugations are connected to corrugations of the third series of corrugations and the corrugations of the second series of corrugations are connected to the corrugations of the third series of corrugations.