The P&ID and Its Uses

Piping and instrumentation diagrams (P&IDs) are the graphic and symbolic summation of the processing aspects of a facility. Although the piping, instrument and equipment information collected on a P&ID can be found elsewhere in a facility’s design records, only the P&ID displays them in comprehensive, coherent relationship to one another.

Activities in which P&IDs have a key role include the following:
• Design and design review. Defines piping, instrumentation and control systems
• Design and construction progress. Provides a graphic framework in which to monitor design and construction
• Construction completion check. At plant completion, the construction agency (either a contractor or Company) is responsible for delivering completed asbuilt P&IDs. This permits a piece-by-piece review of compliance with the design
• Startup. Provides critical information during startup of a new facility
• Operation. Provides the primary source of operating information and training aid for a plant or facility
• New engineer training. Provides a sound example from which to design similar facilities
• Maintenance planning and safety. Provides a framework for planning and monitoring cleanup and isolation, inspection, and similar work prior to startup, as well as future maintenance
• Governmental communications. Provides a vehicle for communication with regulatory and governing agencies
• Additions and modifications. Up-to-date P&IDs provide a basis for estimating, design and implementation of future additions and modifications