This would be easier and you would have more control if you use Contoured Flange rather than Flange.
You will have to have at least minimal rips and solder or weld to close the seams.
If you want overlap add corner feature as shown.
Please mark this response as "Accept as Solution" if it answers your question.
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http://home.pct.edu/~jmather/content/DSG322/inventor_surface_tutorials.htm
http://www.autodesk.com/edcommunity
Still waiting for -Draft option on any Rib feature.
