The Bottom Unheading Valve Chute, also called the Discharge Chute, is a pipe that has a flange on the top end. This flange bolts to the bottom of the Unheading Valve. The chute passes through the hole in the floor of the bottom unheading deck immediately below the coke drum flange. The purpose of the Chute is to funnel the coke passing through the Unheading Valve during the cutting operation to the deck below where it is directed to the coke pit, rail cars, or crusher cars. The Chute is not a pressure containing device. The Chute length is specified during the design stage so that it remains engaged with the hole in the coke deck floor as the drum expands and contracts. The bottom end of the Chute typically does not have a flange. A seal is placed around the OD of the Chute where it passes through the coke deck floor. This seal acts as a barrier between the vapors exiting the Chute and the bottom unheading deck. Hope this helps.