US Patent 7628287 Reusable container unit having spaced protective housings

A hazardous material transport container employing a conventional 55 gal. ring ribbed drum in which a protective shell is slidingly fitted, wherein the shell contains an inner containment vessel, wherein protective spacings are provided between the shell and the vessel and between the shell and the drum, wherein a plurality of elongated strengthening ribs are affixed generally longitudinally to the outer surface of the shell and lie closely adjacent to but slidable within the inner surface of the drum, wherein an upper portion of the shell is welded to a top inner portion of the drum wall, and wherein thermal insulating and impact resistant materials substantially fill the protective spaces.