agri....
Lets make sure that we are talking about the same things..
"Piping design" as commonly used refers to the physical layout, material, flange and valve selection of piping systems.
"Process engineering" refers to the development of PIDs, flowsheets and the mass and energy balances necessary to design a piping system. Process engineering commonly includes the sizing, but not the layout of piping systems.
Process engineering must start before piping design.
What are you talking about ??
-MJC