Your dilemma illustrates the importance that boundary conditions have on the overall response of the model. I agree with the comment about using specific flexibilities for your nozzle condition. You have limited automatic options here (WRC-297, API-650, and BS-5500), all of which have their own set of rules and limitations.

The <em>finite element</em> option is probably your best alternative. If you don't have access to the necessary software, perhaps assistance from outside could be considered.

Another alternative to check would be the cooler manufacturer. Can they provide the necessary nozzle flexibilities? After all, they gave you the load limits ...



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Regards,
Richard Ay (COADE, Inc.)