I have two concerns about modelling and dealing with tank nozzles:

1. The displacements that are calculated by Caesar II according to API 650 due to the bulging effect are the "unrestrained" displacements. Since the nozzle will be connected to a piping system that has its own flexibility and weight and thermal effects on the nozzle, I think imposing those calculated "unrestrained" nozzle displacements to the whole system is not the true case and not correct.

2. Imposing the "unrestrained" tank nozzle displacements at the nozzle will cancel the nozzle flexibility resulting in very high loads which are not true, and that is what I got after a trial run.

My understanding, is that there is no way to get "near" true loads and displacements on the nozzle but to model the tank elements to account for the vertical and radial thermal growth, and completely ignore the "unrestrained" shell rotation, as imposing those displacements on the tank nozzle will cancel the shell flexibility out of the analysis and result in unrealistic very high nozzle loads.

Please correct me if I am missing anything.