What are piping and instrumentation (P&ID) diagrams?

A piping and instrumentation diagram (P&ID) shows the piping and related components of a physical process flow, most commonly used in the engineering field to represent key piping details, control schemes, safety requirements, and operational information.

A process flow diagram (PFD) is a simplified or conceptual design that shows fewer details and provides a bird's- eye view, while a P&ID is more fully developed with detailed piping, instrumentation, and control schemes.

A P&ID should include mechanical equipment with names and numbers, all valves and identifications, process piping sizes, flow directions, control inputs and outputs, interlocks, and interfaces for vendor-delivered components.

P&IDs are typically created by engineers designing manufacturing processes and are used by field techs, engineers, and operators to understand processes and instrumentation interconnections, and to train workers and contractors.

P&ID symbols adhere to ANSI/ISA's S5.1 standards and include standardized representations for equipment, piping, vessels, heat exchangers, pumps, instruments, and valves based on ISA S5 standards.

Yes, P&IDs can be created digitally using software like Lucidchart, which offers ISA S5-standard shapes, drag-and-drop functionality, and collaboration features.

P&IDs are not drawn to scale or geometrically accurate, and there is no universally accepted standard, so they may look different from company to company based on internal standards and software preferences.

P&IDs are foundational to maintenance and modification of processes, provide the basis for developing system control schemes such as HAZOP, and serve as vital reference documents for process safety management and management of change.