Closure for pressure vessels

A closure for a pressure vessel, comprising:

• a hub adapted to fit on to an opening on the pressure vessel;
• a door connected to the hub;
• a hinge assembly to secure the door to the hub;
• and
• a locking assembly attached to the door,
• wherein the locking assembly includes a slide lock operating around a central support, a plurality of locking lug arms radially actuated by the movement of a door handle, the door handle being connected to a side plate attached to the central support, wherein the plurality of locking lug arms are connected to the central support,
• wherein each locking lug arm is guided inside a groove on the hub by a lug bushing;
• wherein the door handle moves the locking lug arms from a locking position on which the locking lugs are seated into the grooves of the hub to an unlocking position on which the locking lug arms are out of the grooves of the hub;
• and,
• a pressure alert valve removably connected to the central support, said pressure alert value preventing movement of the locking lug arms when so connected to the central support.