Abstract: A method of replacing an outwardly opening manhole cover that provides access to the interior of a tank or the like with an inwardly opening cover that includes the steps of removing the outwardly opening cover from the bolting flange of a tank installed manway and attaching a mounting flange to the manway bolting flange. A pair of hinges are connected to the mounting flange and an inwardly opening cover assembly is rotatably mounted on the hinges. The cover of the assembly is arranged to close and seal against either the mounting flange or the inner rim of the existing manway.

Abstract: A large volume, thermally insulated tank is formed by constructing the tank sidewall in superimposed sections. Each section is constructed without the use of external support forms by laying a first outer course of thermal insulating material and then forming a first inner course of refractory material spaced therefrom. The cavity between these two courses is then filled with cementitious material, and the process is repeated until a tank wall of the desired height is completed. The resultant tank wall will have an outer layer of light, thermal insulating material, an inner layer of refractory material and a core of cementitious material joining the two layers.