Means for securing and sealing large diameter hatches in vacuum and pressure vessels

Claim 1

A REMOVABLE HATCH FOR A LARGE PRESSURE OR VACUUM VESSEL PROVIDED WITH A LARGE OPENING TO BE CLOSED BY THE HATCH, THE HATCH COMPRISING: A RIGID HATCH PLATE CONFORMING TO THE SHAPE OF, BUT SLIGHTLY SMALLER THAN, THE OPENING; A FIRST SET OF SPACED LUGS SECURED TO THE VESSEL AND PROJECTING BEYOND THE EDGE OF THE OPENING TO ENGAGE THE INNER SIDE OF THE PLATE; A SECOND SET OF SPACED LUGS SECURED TO THE PLATE AND PROJECTING BEYOND THE EDGE OF THE PLATE TO ENGAGE THE OUTER SIDE OF THE VESSEL; MEANS FOR REMOVABLY SECURING THE PROJECTING PORTIONS OF EACH SET OF LUGS TO PLATE AND VESSEL, RESPECTIVELY; A RING FLANGE MOUNTED ON THE OUTER SURFACE OF THE VESSEL ADJACENT TO AND SURROUNDING THE OPENING THEREIN; A SECOND RING FLANGE MOUNTED ON THE PLATE ADJACENT THE EDGE THEREOF; A SEPARATE COVER FLANGE MOUNTED ON EACH RING FLANGE AND EXTENDING TOWARDS THE OTHER RING FLANGE, WITH A CLEARANCE SPACE BETWEEN THE OPPOSED EDGES OF THE TWO COVER FLANGES; AND SEALING MEANS REMOVABLY SECURED TO BOTH COVER FLANGES ADJACENT THEIR OPPOSED EDGES AND EXTENDING ACROSS THE CLEARANCE SPACE BETWEEN THEM FOR SEALING THAT SPACE.