Maintenance Q&As

What is a P&ID?

Answered July 28 2019

A piping and instrumentation diagram (P&ID) is a picture of the piping, instruments and controls for equipment in the process industry. It shows the control data, start-up and shutdown procedures, safety information, regulatory requirements, and operational details. The diagram illustrates how the branches, instrumentation, reducers and valves fit and work together to meet the needs of a particular process.

Example P&ID Diagram

Labeling Requirements

Although many pieces of critical equipment may contain the information in a P&ID within the details of its asset records, it can be very useful to tag individual components as well. The schematic of the P&ID contains a wide range of symbols that correspond to individual parts. By tagging parts to match the P&ID, a process company can organize unique collections of pumps and values easily, assemble and disassemble a process in a structured way, and record data such as specifications and materials for quick access when needed.

Database for Continuous Improvement

According to AICHE, the information in a P&ID is really just like a relational database of objects put together in a logical manner.

As a result, the P&ID is not only a one-time tool to be consulted at the beginning or end of a process, but something that should evolve over time.

As operation technicians work with the processes within a facility, they will discover ways to improve the system or see potential problems within the process.

TIP: By having a centralized computer system like a CMMS that contains P&ID tag data, it becomes easy to communicate those improvements to those who can make them.

In addition, a process related to production may need to be altered in order to address production or capacity changes. The P&ID can help provide the information on how to build out or reduce that process to meet current needs.

Foundation for Future Audits

Many companies will be required to conduct a process safety management audit or a hazard review from time to time, which requires accurate and current data. The P&IDs, along with the tagging data, can serve as an important resource in which to conduct those periodic audits and evaluations.

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