Non API 650 nozzles

If the nozzle geometry does not satisfy the API 650 requirement, then do we have any other method to evaluate the nozzle loads?

Any thought will be appriciated.

FEA

So shall we consider nozzle stiffness per API 650 and then do the FEA?
Or there is any other way to follow

Thanks,

Appendix P (API-650) states its range of applicability. If you're outside this range, everything from this appendix is suspect.