Image Number 3 for United States Patent #4057170.
A cargo container door construction is disclosed. The construction utilizes a relatively thin sheet metal door skin having a plurality of formed-in longitudinally extending stiffener grooves, with the door edge parallel to the grooves being formed into stiffener edges comprising a lip with a recess on its inner side. One such edge supports hinges which connect with a surrounding frame of a cargo container. The two remaining edges of each door lying perpendicular to the grooves, are each stiffened by an elongated bar and plate which are welded continuously to the edge of the skin and which form closed end walls on the grooves. The bar and plate establish edges which are similar to the lip and recess formed edges and the sides of the door, so that a uniform peripheral edge results. The lip and recess at each edge seat a gasket for sealing the door or pair of doors with a cargo container frame. Longitudinally-extending locking bars, which engage with the container frame, are mounted near the stiffener grooves to withstand closure stresses.