A sealing gasket for providing sealing in a mounting gap on a furnace body where a rotating control member is positioned, is located in a mounting opening and includes a sealing wing, in contact with the wall of the body, a retaining member in contact with the outer surface of the furnace body, and at least one bump form extending towards the control member at the continuity of the retaining member and in the direction of the gasket extension for preventing water from reaching to the control member and furnace body.