What is a P&ID and Why is it So Important?

P038ID example as-built management

At As-Built Management, we work in a very complex field. We have decades of experience in designing new or redesign mechanical process systems across many industries. One of our specialties is instrumentation and piping design for liquid product or materials.

This specialty uses a lot of jargon and acronyms that may not be familiar to many of our clients or prospective clients, so we thought it might be helpful to take a few moments to explain one of our most common three-letter abbreviations.

If you work with us long enough, you’re sure to hear us talking about P&IDs (Piping and Instrumentation Diagrams). To us, P&IDs are second nature and something we work with every day, but to the layman, P&IDs can be much more difficult to understand.


P&IDs: The Basics Explained

On a very simple level P&IDs are essential in the engineering and design of piping systems and process plants. By diagraming the functional relationship of piping, instrumentation and equipment components, they illustrate the interaction of the process components used to control an entire process.

P&IDs include equipment, physical sequences of process branches, valves, instrumentation reducers and control interlocks.


Why Are P&IDs Important?

Obviously, P&IDs are essential to the design of a specific process. However, they are also important to the maintenance of the equipment used and the ability to adjust the process that they represent.

For processing facilities like those in the food and beverage industry P&IDs show:

  • Essential piping and instrument details
  • Safety and regulatory regulations
  • Start-up and operational information
  • Shutdown and control processes

In addition, P&IDs are useful to:

  • Serve as a foundation for programming controls
  • Create standards and guidelines standards for the overall operation of the facility
  • Assess the construction processes
  • Produce instructional documents
  • Create a universally accepted language for communication regarding plant operations
  • Create safety and control philosophies
  • Form equipment and design cost estimates

What Should All P&IDs Include?

Unlike many of the aspects of our industry and those that we normally find ourselves working with there are no set standards for P&IDs. However, engineering firms that produce P&IDs agree that they all should include the following:

  • Instrumentation and designations
  • Mechanical equipment with names and numbers
  • All valves and their identifications
  • Process piping, sizes and identification
  • Miscellaneous – vents, drains, special fittings, sampling lines, reducers, and increasers
  • Permanent start-up and flush lines
  • Flow directions
  • Interconnections references
  • Control inputs and outputs, interlocks
  • Interfaces for class changes
  • Quality level
  • Annunciation inputs
  • Computer control system input
  • Vendor and contractor interfaces
  • Identification of components and subsystems delivered by others
  • The intended physical sequence of the equipment

We won’t take the time to dive into each of these elements one by one, but ensure any P&ID you commission includes all of the items listed here. If not, you could be working from an incomplete document that will cost you time and money to fix.


As-Built Management and P&IDs

ABM is a professional engineering services firm with years of project experience in manufacturing, operations, & management within a variety of industries. We have produced countless P&IDs for Fortune 500 manufactures from all across the United States.

Whether you’re setting up a new manufacturing process or are making changes to an existing line, As-Built Management has the experience to develop a comprehensive P&ID that will create greater operating efficiencies and improve your company’s bottom line. Contact us today for more information.

Source: PIC001: Piping and Instrumentation Diagram Documentation Criteria

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