windu,

The curious feature of the piping is the smaller 762 mm diameter at the node 140 connection. It would be more benefit to use a smaller diameter expansion joint there being more flexible. That would also reduce the cost of the second expansion joint. The 762 mm diameter is a large size, though smaller than the first expansion joint.
A simple straight system is stiff, while more flexibility is needed. The piping system could have been more flexible with a equipment arrangement that would have allowed more offset and length of piping for flexibility. The small lengths of large diameter piping require more complexity, not a simple system, to achieve adequate flexibility. A more flexible piping route might have turned to 'Z' first and then turn '+X' to loop back to the node 140. There would then be three or four elbows to provide more flexibility in the piping. The elbows of 1219 mm piping would take much space that might not be available.