It is designed not to be fully sealing, but with sealing air connection could be zero leakage when applied sealing air. It is designed with inspection hatches for manual soot cleaning when required.
The flue gas damper with double combined discs is operated by manual clutch or single pneumatic actuator (could be FC or FO position when power failure).To close the damper, each damper disc touch the sealing rings (two couple of malposed half rings) to get the plane sealing effect; the damper shaft and half rings are unique designed for surface sealing; both side of shaft end are sealed with H.T. resistant soft material stuffing. The air sealing connection for sealing air (sealing air pressure is slight higher than the flue gas pressure) is option according to customer’s requirement.