I am trying to develop a script to change pipe sizes based on the flow parameter but pipe fittings don’t have it, does anyone have any idea to change the pipe and the connected pipe fittings size?
Look into the MEPover package. It has nodes for getting connected fittings and full pipe runs.
You would check your pipe for flow values and then find the connected fittings to know which fittings to adjust along with the pipe. You may have to determine flow direction or watch out for pipe transitions depending on how things workout.