I suspect it wasn't the flanges, but the welding that resulted in the problem. There doesn't seem to be enough load on the seams to result in failure when running up on the ground.
John Thorp was the Lockheed connection I mentioned previously. His tank designs were butt welded. Another friend, a top level auto engineer with extensive tank design experience felt flange welds were fine. all else being equal.
FWIW
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Marc
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