Model piping arrangement:
There are multiple options to model connected piping to a Vessel / Tank surface, here is one modeling approach.
See WIKI here for other modeling approaches
Insert Vessel / Tank
Insert internal piping with rigid options to surface of Vessel's / Tank's end Cap.Insert User SIF =1.0 at junction to overrideall other SIF calculations
Optional: Take credit for flexibility in end cap
Connect internal piping to inner surface of end Cap, then insert nozzle element tooutside surface of end cap.
Insert piping connected to nozzles
Also recommend to insert a User SIF at thesurface of the nozzle connection to the end cap.What value should be used, may need to handcalculate this value or use another software to provide that information, this would not be atypical code calculated SIF value.
Optional: Report Allowable forces and Moments
Insert reference points at nozzle connection to end cap to report loads that exceed allowable forces and moments.
Insert End cap to account for weight
Model piping connected the end of a tank / vessel