Plant Documentation Series: Piping & Instrumentation Diagrams (P&IDs)

Week Three: Piping & Instrumentation Diagrams


What are they?

Piping and Instrumentation Diagrams (P&IDs) are one of the most critical tools across operations support teams. As the blueprints for a manufacturing facility, they contain all process-related assets and their connectivity. Therefore, P&IDs are a holistic resource for understanding how the process is controlled – visualizing all process equipment, piping, and instrumentation.

Beyond being an essential tool, they’re also required process safety information for many manufacturing plants as part of the safe management of hazards associated with processes using, storing, manufacturing, or handling highly hazardous chemicals (see: OSHA 29 CFR § 1910.119)

A P&ID | Credit: Creative Engineers Inc.

Just like Process Flow Diagrams and Isometrics, P&IDs are a deliverable during the initial construction project. They illustrate the facility from raw material unloading to finished product off-loading, including auxiliary systems. Though the concept is simple, these drawings contain a significant amount of valuable information about the process:


  • Major process equipment transforming raw materials into the final product, including everything from large tanks, towers, and reactors to small pumps

  • Equipment information summaries typically include equipment IDs, descriptors, dimensions, materials of construction, design and/or maximum allowable pressure/temperature, horsepower, duty, # of tubes, etc.

  • Minor process equipment such as blinds, valves, vents, drains, etc.

  • Piping and associated line numbers coded to signify information such as fluid service, piping size, class, and insulation

  • Instrumentation and interconnecting signals that allow monitoring and control of the process



How are they used?


P&IDs are the basis for everyday decisions in industrial facilities. They visualize the plant configuration and can be accessed away from the field. Remote access to P&IDs allows facilities to reduce personnel risk, too.

A P&ID broken down to HAZOP nodes

As we’ve previously mentioned, P&IDs can be critical in reducing human, environmental, and economic loss. They serve as reference tools when conducting incident investigations and preparing process hazard analyses (PHA) like HAZOPs, what/ifs, and checklists. P&ID visualizations also support the proposal, evaluation, and implementation of process changes within a facility’s Management of

Change (MOC) structure.


P&IDs commonly support different types of troubleshooting. For example, when an upset occurs, P&IDs are an immediate reference tool for identifying upstream & downstream equipment that could be affecting the process.


Because P&ID use is so ubiquitous, they serve as a great learning tool to train new personnel. For existing employees, P&IDs provide a quick reference to the process and act as an important communication tool. P&IDs are commonly used to communicate maintenance needs, identify isolation bounds, and visualize project scopes.


As you can see, there are a variety of plant personas and tasks that use P&IDs, making it one of the most common reference tools in the plant.



What are the common challenges of using P&IDs?


While P&IDs contain a wealth of information, there are common pain points that plant personnel encounter when trying to use them in their current form:


  • It can be hard to find the right P&ID – P&ID libraries can be overwhelming, numbering up into the thousands for a single site! In some cases, brownfield P&ID libraries contain an equipment index page to help readers find major equipment for an area. But if you are trying to find minor equipment and instrumentation, you probably need to have some tribal knowledge – or ask someone who does.

  • P&IDs contain too much information – While all that process control information is essential, it can make interpreting the P&ID time-consuming. Some P&IDs are jam-packed with information, either right from inception or due to small additions over time. (We like to joke that reading P&IDs is an art form!)

  • P&IDs contain too little information - Even in their "jam-packed" state, users will find some equipment unlabeled on a P&ID. This can be problematic in situations like performing a LOTO - where unlabeled minor equipment creates ambiguous procedures and increases safety risk.

  • Static P&IDs can get out of date fast! – Because of their widespread use, P&IDs can fall out of sync. In situations where users have hard copies, any new change immediately puts the P&ID out of date. Even with digital repositories, multiple groups may check out the same diagram and request updates. These inconsistencies create a tall task for drafters to true up the information into one source of truth.



How P&ID Digitization can support a better field experience:


Digitization of P&IDs is more than just re-creating the drawing on a computer.


Bringing P&IDs into the digital world transforms a wealth of process information into a digital foundation for any industrial site. P&ID Digitization allows for advanced search, navigation, analytics, and interaction with a modern interface to enhance current workflows and develop new capabilities.


At a high level, our team sees a variety of ways that P&ID digitization can provide benefits to plant personnel:


  • Faster, smarter troubleshooting – Improved searchability of P&IDs reduces the time spent finding process & equipment information in an upset, non-optimal operation, or even an emergency.

  • Improved accuracy of process safety information – Reduce the headaches associated with out-of-date P&IDs and increase trust in critical plant documentation.

  • Improve searchability & digestibility – Quickly query or filter for the level of information that you need. Find specific valves to help build your LOTO procedure or filter out information when tracing utilities.

  • Support collaboration in the field – Quickly generate P&ID visualizations and easily share them with others when building procedures and documentation, such as a work scope packages.


Have additional ideas? We do too!


Stay tuned...



This blog is part of Cerebre’s Plant Documentation Series. Our previous posts in the series include:


10/12 - PFDs (link)

10/19 - Isometrics (link)


As the industrial world races into digital, plant documentation is an important tool for everyday decisions. Specifically, there are many different kinds of industrial drawings used to support process, safety, mechanical, and management decisions.


We see tremendous opportunity in how the digitization of these documents can support a variety of digital and field objectives and want to share that with you!