Read about START-PROF pipe stress analysis software
The idea of modular design is following. The complex piping system is divided into several modules that is mounted on a frame structure. Modules can be transported to the site and joined to each other into entire piping system. One of the modules is shown on the picture below. At the points "1" external piping or other module piping are connected.
Stress analysis of separate module for temperature expansion and other loads acting on a whole system is impossible. Only whole system can be analyzed. Exception: when fixed anchors are added at all connection points between modules. But in this case design for temperature expansion will become extremely hard.
The practical solution for this problem is following:
Option 1. Module manufacturer perform it's stress analysis with using of several, the most unfavourable variants of external piping design. Stress analysis should be successful for all variants. After that manufacturer pass the START-PROF module piping model to customer. Customer adds the module model to own piping model and perform analysis of the whole system.
Option 2. Customer adds fixed anchors or moment free anchors at the points, where his piping model is connected to module. Performs stress analysis and optimize design. After that he pass the START-PROF piping model to the module manufacturer, who join this model to the module piping model and preforms whole system stress analysis.
Transportation stage should be calculated for both options described above. The system should have transportation configuration (locked springs, added temporary supports, detached flanges etc.) and analyzed for inertial loads and vehicle body deformations during transportation. Added ice, show, wind, impact, and other possible loads.