Hello,

Yes, it is a requirement in ASME B31.3 Appendix D. However, you can try ASME B31J if it is there or FEA using FEA Tools and see if this will help. Maybe the flex factor using the alternative methods might be different.

If you have a high temperature system, using hot elastic modulus will help to reduce nozzle loads.

Just correct any wrong statement I've made.

Warm Regards,