<p>COKE OVEN CHUCK DOOR A coke oven chuck door has a metal sealing member which has springiness and flexibility and is supported cantilever fashion on the inside of the door frame. An insulation block is interposed between the sealing member and door frame. The sealing member has a knife edge flange which extends around its perimeter and is automatically aligned with a sealing surface on the main door on which the chuck door is mounted.</p>