Piping & Instrumentation Diagram Series


Drafting Guidelines for P&ID’s

  • Suitable  line thicknesses are shown at full sizes
  • Crossing lines must not touch-break lines going in one direction only. Break instrument lines crossing process and service lines.
  • Keep parallel lines at least 3/8″ inch apart.
  • Preferably draw all valves the same size-1/4-inch long is suitable-as this retains legibility for photographic reduction. Instrument isolating valves and drain valves can be drawn smaller, if desired.
  • Draw instrument identification ballons  1/4-inch up to 7/16th-inch diameter.
  • Draw trap symbols 3/8th-inch square

Next time:

Flow lines on P&ID


Total Cad Systems Inc.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: