Closure for pressure vessel

Claim 1

A closure mechanism for use with a pressure vessel having an annular area defining a circular access opening therein, comprising a circular cover having an external diameter less than the internal diameter of said access opening, an annular gasket supported about the periphery of said cover and having an external diameter slightly larger than the internal diameter of said access opening to seal said cover to said vessel when said cover is positioned in said annular area with the plane of said gasket parallel to said opening, cross brace means positionable across said opening in engagement with said cover for holding said cover in a closed position against the pressure exerted thereon when said vessel is pressurized, double hinge means connecting said cross brace means to said vessel adjacent said access opening to permit said cross brace to be moved parallel to said opening and to be swung outwardly away from said opening, latch means carried by said vessel at a location for locking engagement with said cross brace means when it is moved in a direction parallel to said opening toward said latch means, and for preventing outward swinging of said cross brace means when it is positioned across said opening in locking engagement with said latch means, and means pivotally connecting said cover to the said cross brace means about an axis parallel to the pivotal axes of said hinge means to permit tilting of said cover into said vessel out of sealing engagement with said annular area while said cross brace means is in a locked position across said access opening and thereby permit movement of said cross brace in a direction parallel to said access opening out of latching engagement with said latch means, said tilting of said cover into said vessel being opposed by the pressure in said vessel, whereby said closure mechanism prevents accidental opening of said cover while said vessel is pressurized.