Abstract: The invention relates to on-off valve, particularly for insulation by-pass of exhaust gas expansion turbines of catalytic cracking plants, of the type comprising a hollow valve body, an opening for the inlet of the gas into the valve, an opening for the outlet of the gas from the valve, at least a shutter and the relevant at least one seat, the valve being characterized in that it comprises a conduit coupled to the inlet opening and a conduit coupled to the outlet opening, the at least one seat being coupled to the inlet conduit or to the outlet conduit and the at least one shutter having a cover shape and sealing engaging with the seat by a rotatory motion transmitted to the shutter by an actuator by a drive shaft and a drive arm.

Abstract: The invention relates to on-off valve, particularly for insulation by-pass of exhaust gas expansion turbines of catalytic cracking plants, of the type comprising a hollow valve body, an opening for the inlet of the gas into the valve, an opening for the outlet of the gas from the valve, at least a shutter and the relevant at least one seat, said valve being characterized in that it comprises a conduit coupled to the inlet opening and a conduit coupled to the outlet opening, said at least one seat being coupled to the inlet conduit or to the outlet conduit and said at least one shutter having a cover shape and sealing engaging with said seat by a rotatory motion transmitted to the shutter by an actuator by a drive shaft and a drive arm.