The invention relates to a shut-off device for valve systems of industrial plants, in particular of chemical and petrochemical plants, with a disc (12) to shut off an opening for a fluid flow and with a seal seat (13a). The invention is characterised in that the disc (12) is arranged between the seal seat and a pressing means (26) to subject the disc (12) to a pressing force and can be pressed by the pressing means (26) against the seal seat (13a), wherein the pressing means (26) has in a housing (10) a plurality of pistons (48) and a transmission element for transmitting the pressing force to the disc (12), the transmission element being arranged between the pistons (48) and the disc (12) and extending along the disc circumference, and wherein the pistons (48) are fluidically connected by a feed line (49) for hydraulic fluid.