Dear All,
I need to verify a Copper-nickel water line as per ASME B31.3. There is a 10" header and six branches that connect the header to the two vessels by six nozzles (as per sketch attached).
Conservatively, I have considered an anchor at nozzles, But I think to be was too conservative; Operating stress (W+P+T) is only a little bit lower than allowable stress (safety factor= 98%<100%).
Then How Can I model the nozzles in order to avoid high stress values on the piping system and high forces at nozzles?

Consider using the WRC-297 flexibilities at the vessel connections.