If its your 1st time modelling Jacketed pipe suggest you visit the Caesar II 'Jacket' example file and the manual has a step by step on how to model it.
As for Vacuum pressure can someone please answer this? I know 5.2 version does not take negative pressure for 'buckling' reasons. But if we are still using 5.2 for project purposes how should we input negative / FV pressure for jacketed piping?