First of all, prior to starting to build a piping model you have to know what you wish to achieve in any analysis.
1) Determining the stresses in the system and comparing with the range allowed by the Piping Code
2) effect of piping loads on the rotating equipment nozzle
3) effect of piping loads on the heat exchanger, pressure vessel or tank nozzle?
4) the piping loads on the structural supports such as V-stop and anchors
5) movements of the piping system due to thermal growth or contraction
6) effects of wind loads, Wave Loads, erathquake and other occassional load cases on the piping system and/or attached equipment
7) effects of soil resistance to movement for underground or buried piping system and/or any attached equipment
8) effects of changes in temperature, pressure and weight on flanged couplings and to determine if there is a tendency for the connections to leak?