A flange plate closure for accessing a containment vessel has a metal base plate, having an interior and an exterior surface, at least one vertical metal tube having an open end, a metal flange ring at said open end defining an upper planar surface, and a lining made of non-corrosive material. The lining is disposed in overlying relation to the interior surface of the base plate, the interior of the tube and the upper planar surface of the flange ring. The lining is rigid, and is mechanically affixed to the metal components. The lining is made of Ultra High Molecular Weight Polyethylene.