Abstract: A valve arrangement for a pressurizable vessel includes a valve member mountable on a vessel for movement relative thereto. The valve member is formed with a passage which extends over part of the length of the valve member. A valve-actuating assembly is removably mountable on the vessel. The assembly includes a fitting surrounding the valve member with clearance at the exterior of the vessel, a housing movably mounted within the fitting, and force-transmitting elements partially received within the housing and operative for displacing the valve member between an open position in which the passage communicates the vessel interior with the clearance so as to permit fluid flow between the interior and exterior of the vessel, and a closed position in which such fluid flow is prevented.