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Text Box: P&IDs—From The Drafter’s Perspective
Guide To Drafting Piping and Instrumentation Diagrams

P&ID Drafting Tips Archive

P&IDs - From The Drafter’s Perspective—Guide for Drafting Piping and Instrumentation Diagrams

Never draw P&IDs on a scaled border.   Flow diagrams are not drawn to scale as they are graphic representations of flow and do not represent actual sizes of equipment or instrumentation. 


Always draw P&IDs to fit within a 22”x34” or 24”x36” border, depending on what the company’s plotting standards call for.  Symbols from P&ID menus are configured to fit those border sizes.   If menu items are placed within scaled borders, text contained within symbols will be too small to read when the drawing is plotted to 11”x17”. 


Many companies plot P&ID drawings, to be issued in packages, 22”x34” because when they are folded, they fit perfectly with letter sized documents.

Tip #1

Disclaimer:  The web has been scoured to provide as much information about P&IDs as possible on this site.  This information comes from many sources and many different countries.  Reviewing it all will increase a person’s knowledge but it is the reader’s responsibility to insure that the information contained herein is verified by proper authorities as valid for use in any intended application.

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Tip #2

Rarely do two different designers mark up project drawings the same.  Some leave out vital symbology while others show every detail.  Do not simply draw what is shown on the mark-up.  If it is obvious that more should be shown, then show it.  Provide the designer with the project’s Symbol and Legend sheet and ask them to follow those symbols when marking up the drawings.  Be consistent.   Always keep a copy of the project’s current Symbol and Legend sheet near for easy referral.


Study the entire drawing before picking up any marks.  Make a list of questions, to ask the P&ID Lead, about anything that is not clearly marked.  Anything the P&ID Lead can not answer, take to the designer.  Try not to interrupt the designer more than once per drawing. 

Tip #3



Text style for P&IDs should be Simplex font.


There should be no text smaller than 1/8" on the body of a drawing unless absolutely necessary.  Text must be of adequate size to produce legible reproductions on reduced size prints of drawings.


Text width should always be 1.00 unless that is too wide for the working area.


All text must be inserted where it does not appear to be upside down or at an angle.  When reading a drawing vertically or horizontal (that is rotating the drawing clockwise), all text must be able to be read without turning the drawing.

Tip #4

Newly minted drafters frequently make the mistake of thinking that speed is the quality which will be most appreciated by their new employers.  Most are surprised to learn that the very people they are trying so hard to impress with their quick turnaround, would much prefer that they slow down a bit and concentrate more of their efforts on accuracy.


A drafter who thoughtfully picks up red marks and self back checks each drawing, before turning in the finished product, will more quickly gain the respect and trust of experienced drafters and designers, over  one who behaves as if they are always in a race to win a prize.


Less mistakes (accuracy) will actually lead to increased speed in the long run because costly rework will be avoided.  Motto for drafters—Get it right the first time.

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Tip #5

CAD Drafting Contests

This isn’t really a drafting tip but it is pretty cool anyway.  Test your drafting skills.  Compete with others to win cash prizes.


Browse contests for Aerospace, Electrical, Interior Design, Architecture, Machine Design, Oil and Gas and more at CAD Crowd website.

Tip #6

Color Code for Marking Up P&IDs


Marked up drawings should always follow the same color code.  If drawings are received which are not color coded correctly, provide the following list to the person who marked up the drawing.


red - incorporate items (add)

yellow – items marked as “correct” by designers

green - delete items

blue or black - comments to drafter or designers personal notes (do not add to drawing)

orange - items addressed by drafting (pickups) – to check your own work.


When drafting, always check your work twice.  As you make each change, use a thin orange line on the mark-up to show yourself that  picked up the mark.  Do not use heavy slashes.  And don’t cheat by making all your marks at the end...do each mark individually.  While back checking the print of the newly edited drawing, circle each change on the mark-up with a thin orange line.  At the same time, use the orange line method for each change on the check print.  Always use this method to self-check and you’ll rarely miss any marks.