Abstract: A closed system that eliminates worker exposure during coker vessel decoking operations and thereby significantly reduces risks to workers also increase coking capacity by reducing the coking cycle time. The closed system preferably comprises a coker vessel with a side entry feed line attached to the vessel above the vessel bottom; a closure housing with laterally moveable closure member therein sealed to the vessel bottom either directly without, or indirectly with an adapting spool member and; a coke chute sealed to the bottom of the closure housing. The system can be remotely and repetitively operated through numerous coking/decoking cycles without removal of any system element.