We have Transition Nozzle of DUplex(UNS 31803) air cooled HX .
Now this is non standard and we need to form out of Pipe Sa 790.
If we formed it out of pipe then Div-2 is not listed Sa 815 in their material List.
Now Q is
-How we certify the formed product in Div-2 then ?
-Can we certify Nozzle as Plate material with (Like we formed dish) having supported by fiber elongation calculation?

Please reply expert opinion.

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Niraj