How to read P&ID’s to get most out of it

A: A: Line size, service code, material family, and flange class are encoded here. That's exactly what the tag gives you. B: Class 150 is a flange rating, not MAWP. Pressure depends on material and temperature. C: Corrosion allowance is a line class detail, not readable from the tag alone. D: Temperature derating exists. Class 150 at 200 °C is already constrained.

A: A: Low suction reduces available head; the FCV sees low flow and opens, driving recirculation. B: A trip only occurs if a PSL is shown; many pumps don't have it. C: With lower suction, differential head falls, not rises. D: Level control is downstream and reacts slower, if at all.

A: A: Control duty plus pressure regulation points you to globe-style trim. B: Ball valves shut tight but behave poorly in continuous throttling. C: Gate valves aren't built for modulating service. D: Size alone doesn't drive valve type in control loops.

A: A: Stroking the valve first can mask signal issues. B: Sensor to logic to final element matches the signal path on the P&ID. C: Tuning comes after the loop is proven. D: Fail position matters, but not before basic loop continuity.