After spending many years working with and designing sheet metal components, it has become obvious that if one of the major hinge manufacturers were to produce a two part weld on hinge (316L st st) then the design and manufacture of Hazourdous Environment enclosures in Stainless Steel would be so much easier. They would still need certification, but the basic problem of door sealing would be done and dusted. I have seen over half a dozen designs ranging from tapped Block hinges, flat spot weld on hinges, but all have basic faults ranging from cost through to chemical entrapment (electropolishing process). The hinge would need to be designed to allow the door to be easilly located but also for movement in the "Z" direction, a simple enough thing to do. For some reason some designers either over engineer or simply done understand basic concepts.