Abstract: The invention relates to a shut-off valve 1 for pipelines and/or for tanks that hold liquids. The shut-off valve 1 has two-part valve housing 3 with a passage opening 4. In the passage opening 4, there is likewise a sliding and/or rotatably supported, spherical closure element 5 that likewise has a passage opening 4′. The closure element 5 is surrounded by two half-shell shaped sealing shells 6, 7. The sealing shells 6, 7 form a passage opening 4″ that corresponds to the passage opening 4′ of the closure element 5 and consist of a softer or more elastic material in comparison to the closure element 5. Each of the sealing shells 6, 7, at least on their opposite faces 8, has a ring-shaped device 9, 9′ for purposes of securing between the housing halves, the valve housing 3, 3′ or between the flange 28 of the valve housing 3, 3′.