A closure 10 is provided for retaining fluid pressure within a vessel, and comprises a hub 12 having an access opening to the vessel, with the hub having a circumferential stop 17 and one or more recesses 50 each extending radially outward from an adjacent inner surface 26 of the hub. A door 22 is positioned between the stop surface and the vessel, and a latch member 30 brings the door into sealing engagement with the stop member. One or more lugs 24 each extend radially outward from an exterior surface of the door, such that a respective lug engages the hub about a respective recess to seal the door to the hub, while the door may be moved to pass through the one or more recesses and out of the hub.