When do not pocket is required in P and ID?

A "no pocket" requirement in Piping and Instrumentation Diagrams (P&IDs) is typically necessary when there is a risk of fluid accumulation that could lead to operational issues, such as pressure build-up or contamination. This specification ensures that there are no dead legs or areas in the piping system where fluids can stagnate. It is particularly important in processes involving hazardous materials or where precise measurements and flow rates are critical. Ultimately, it helps maintain system integrity and safety.