A Breakdown of P&ID Methodologies: Pros, Cons, and Costs

Methodologies for highlighting and updating P&IDs varies across plants, but everyone has a vested interested in finding a better way. In this blog post, we identify the four most common industry approaches, break down the pros and cons of each method, and give you the tools you need to make the best decision for you.

Case study Summary Chart

Case study Summary Chart

In our 10 plus years of experience highlighting over 100,000 P&IDs, we’ve done it all: paper and marker highlights, PDF markups, CAD layer markups, and data-driven electronic highlights. But which is best? To answer this, we considered the effort required for each initial highlight, the utility of each method’s end product, the maintainability behind each approach, and the ultimate compliance benefit each provided. We also examined the time and cost associated with each method.

What did we find? In short, data-driven highlighting is well worth the initial setup time involved, resulting in quality compliance data that reduces the possibility of human error. Companies prepared to set up data-driven highlighting significantly reduce labor and costs associated with P&ID QC and maintenance, resulting in a 77.55% cost savings compared to manual highlights. If you’re not quite there yet, CAD layer markups are the next best thing, though they’re laborious for the CAD department to maintain and require scheduling environmental oversight. CAD layer information is also not exportable and isn’t linked in real-time to equipment. Despite this, the CAD layer method still results in a 32.84% cost savings compared to manual highlights. Next best to this is the Adobe or other PDF-markup method with 17.91% cost savings, followed by the traditional marker-on-paper method.

See our breakdown of the four methods below, followed by our time/cost analysis to make the best choice for you.

Paper P&ID Markups (Paper + Highlighters)

Example Paper P&ID Highlight

Example Paper P&ID Highlight

This traditional method includes printing out copies and manually highlighting P&IDs.

Initial Effort

Pros to this method include a limited investment in technology, but highlighting paper P&IDs is a cumbersome process that requires manually tracing every line. Depending on the complexity of the P&ID, it can take up to 45 minutes to highlight a drawing. Mistakes result in one of two choices: reprint and start over, or use white-out (which often ends up hiding equipment).

Utility

This method is better than nothing, but efficiently managing redline markups and updating P&IDs is close to impossible during a turnaround or retag. What’s more, juggling several hundred P&IDs in the field is difficult because you can’t search them easily. Additionally, paper P&IDs can get ruined or lost in the field.

Maintenance

While printing paper P&IDs is a simple process and anybody with a sharpie can make changes, the cost of rework is high. Whenever a change is made, highlighting needs to be started over.  

Compliance Benefit

Manually highlighting P&IDs presents a challenge for maintaining compliance and offers little to no benefit in comparison to newer technology. Juggling field notes amongst P&IDs is a daunting task in high numbers, QC is time consuming, and efficiently recording tag numbers is difficult. It also requires organization and time to combine and merge information from field-recorded pen-and-paper notes.

Adobe PDF Markups

Example Adobe PDF Highlighted P&ID

Example Adobe PDF Highlighted P&ID

Adobe PDF markups involve loading scanned copies of the P&IDs into a PDF editor, such as Adobe, and drawing electronic highlights with the native highlighting tool.

Initial Effort

PDF tools eliminate the need to whiteout (or start over) because of mistakes and the final result is cleaner than a manual highlight. However, the time required to highlight drawings in a PDF editor offers little time savings. PDF viewers were not designed specifically for piping and instrumentation diagrams, so drawing each and every line is a challenge, especially for one-off bleeders and stub-outs. Each line requires two mouse clicks (for straight line markups) or careful and steady hands for free hand-drawn lines.

Utility

With multiple P&IDs bundled in a single file, it is easier to review P&IDs in Adobe than manually. Search functions are available through Optical Character Recognition (OCR), but they’re often limited to text that can be recognized, which constraints functionality. Entering tag numbers is cumbersome, as each valve or equipment piece must be annotated individually. Depending on the complexity of the P&ID, this could double the time necessary to highlight. If highlighted markups are not printed transparently, process line information will remain hidden. P&ID PDF files tend to occupy large large file sizes which make them inconvenient to share.

Maintenance

The ability to copy-paste markups between drawings is one of Adobe’s most advantageous features. Highlighted process streams can easily be modified to change their color. However, if significant changes have been made to the P&ID, the drawing needs to be re-highlighted. Not only does this increase time, it also increases the cost of rework. The time required for simple updates is also greater than that required for paper P&IDs.

 Compliance Benefit

Although it’s a cumbersome process to initially enter tag numbers, once entered, they can be searched to identify and locate valves through OCR technology. However, the inability to export compliance data and the shortcomings of OCR provide little benefit for the time invested.    

CAD Layer Markups

Example CAD Layer P&ID Highlight

Example CAD Layer P&ID Highlight

CAD layers are produced on a vanilla CAD platform created for 2D drawings and can be used to create basic P&IDs. Instead of using a highlighter on paper, a CAD drafter draws a CAD highlight over applicable process lines. As defined by AutoDesk, they can be thought of as transparent plastic sheets kept atop of each other. Each layer has the ability to store basic information such as name, color, linetype, and thickness. Layers can be setup in a drawing template, any additional layers, or subtractions, have to be made for each individual drawing.

Initial Effort

Layer highlights prepared in AutoCAD look clean, and can be managed by the CAD department alongside the P&IDs. Multiple property standards such as linetype and color can be assigned to each layer. However, this is a time-consuming process, as the drafter must manually plot lines over the process lines being highlighted. This includes individual bleed valves and complex piping configurations. Additionally, performing highlights requires somebody familiar with CAD software and environmental regulations.

Utility

CAD layers can be thoroughly searched and do not rely on OCR software. Unfortunately, as in Adobe PDF, highlighted stream information are not exportable. During an MOC, any changes made to P&IDs result in required changes to corresponding CAD layers. Changes to linetype and color must be manually updated, which doubles the work of the CAD department.   

Maintenance

While CAD layers are easy to update, they’re hard to maintain. Any markups made on the P&IDs in the field can be updated, but substantial piping changes may result in rework. This leads to higher costs, and requires additional resources. During the highlighting process, it is crucial for the environmental department to be involved in order to ensure that the highlighted streams have been assigned correctly. However, CAD layers are predominantly handled by CAD drafters. This often leads to clashing schedules, resulting in unnecessary delays.

Compliance Benefit

Layers provide a neat set of P&IDs that are easy to interpret, search, and annotate, providing transparent compliance and an opportunity to enter LDAR tags within the same workflow. Since they’re generally updated with every MOC, chances of overlooking a component are reduced. Unfortunately, layers are not data-driven, so ...

Ei Data-Driven Electronic Highlights

Example Ei Data-Driven P&ID Highlight

Example Ei Data-Driven P&ID Highlight

Data-driven electronic highlights present a unique method for highlighting P&IDs. Data is gathered and used to automatically generate highlights, which results in a workflow-enhancing tool that is also cost effective.

Initial Effort

Ei chemical engineers conduct a review to extract data and information present in your P&IDs. Highlights are automatically generated from the information available and built-in QC checks safeguard against any potential issues (such as lines changing stream name across pages).

Utility

Data-driven electronically highlighted P&ID are easy to search. During an MOC or retag project, information extracted from the drawing is used to populate the facility’s LDAR database. This data can further be utilized to drive QA/QC efforts and leverage compliance. Apart from LDAR highlights, Ei’s intelligent software helps contain BWON, Flare Mapping, and PSM highlights within the same P&ID.


Maintenance

Whether a stream’s applicability determination changes, or whether substantial changes have been made to the P&ID during an MOC, Ei’s intelligent P&IDs are the easiest to update and maintain in comparison to conventional techniques. Unlike layers, which are time consuming,
changes made through Ei Intelligence can be universally applied across P&IDs. Any markups made in the field can be electronically imported into CAD, which simplifies the updating process.

Maintenance does require a CAD plugin use or coordination with Ei.

Compliance Benefit

Data can be exported and compared to equipmen inventory to proactively identify compliance gaps, detangling equipment inventories and compliance. Searchable P&IDs (including searchable tag numbers) increases usefulness and accuracy of MOC process and repair workflow. All equipment and information can be exported into a spreadsheet for review.


Cost Analysis

To analyze the cost impacts of the P&ID highlighting methodologies mentioned above, our Engineering and CAD team calculated the time and cost impacts of each method. The results of our analysis are summarized in the table and chart below.

 
Table: Time Analysis Summary for Leading P&ID Highlighting Methodologies

Table: Time Analysis Summary for Leading P&ID Highlighting Methodologies

P&ID Highlighting Time Analysis Result Summary

P&ID Highlighting Time Analysis Result Summary

Ei’s data driven highlights are 77% more cost effective over traditional paper markups, 60% more cost effective over Adobe PDF highlights, and 45% more cost effective of CAD layers.

Conclusion

There are many P&ID highlighting methodologies used in industry, and each offers different pros and cons. When choosing which methodology you want to use at your plant, it's beneficial to think through the time and cost to perform highlights, as well as the time and cost to update in coming quarters or years. 

For our next post, we'll dive into the time and cost case study, with an emphasis on the payback period (cost to earn back the cost of P&ID highlighting) across various approaches. Check back, or subscribe to our newsletter to get notified when we post.