Shut-off device for gaseous media high temperature

Support structure of a technical plant from non corrosion-resistant material, the inner wall thereof, at least temporarily contains a corrosive and abrasive gas-vapor mixture and is protected from acid corrosion by a gas-steam mixture barrier. This is placed alternatively between a refractory coating (6) and the high heat-insulating layer (7) or in the refractory layer (6) or integrated into the heat insulating layer (7). The mechanical protection against penetration of the gas-vapor mixture through the thermal insulation (7) up to the inner wall of the carrier structure a heat insulating material with significantly reduced thermal conductivity can be chosen and thus the temperature can be lowered on the outside of the support structure, whereby the energy loss reduced and work safety is increased.