What does P&ID stand for?

• A. Process and Instrument diagram
• B. Piping and Instrumentation Diagram
• C. Pressure and Isolation Diagram
• D. Piping and Isometric Diagram

Answer: (B)

Piping and Instrumentation Diagram is the standard name for the drawings that combine piping layout with all the control and measurement devices attached to those pipes. It shows where pipes run, what valves and equipment are in the system, and where sensors, controllers, transmitters, and actuators connect to the process. This level of detail lets engineers design, install, operate, and troubleshoot the plant’s control loops and maintenance tasks, because you can trace a line from a process stream to its valve and to the instrument that senses or controls it.

The other options don’t fit the common terminology. One omits piping and would not be the recognized term for the detailed plant diagram; another suggests a different, uncommon type of diagram; and the last describes a 3D piping drawing rather than the instrumentation and control connections shown in a P&ID.