Abstract: A high pressure seal assembly for use with an insert cover positioned in a downhole tubular housing, the assembly having a flange which is deformable by the pressure differential between higher pressure on the exterior of the insert cover and the lower pressure on the interior of the insert cover. A portion of the flange is deformed to mate against the tubular housing. In a preferred embodiment, the flange has two legs, one being attached to the insert cover and the second being the deformable portion having deformable spacer material positioned between the second leg of the flange and the housing.