A good P&ID should be easy to understand, modify, and use during design and construction. Some common issues I frequently watch for are:

✅ Inconsistent equipment/instrument tags
✅ Missing or incorrect signal lines
✅ Incorrect valve symbols or fail positions
✅ P&ID not matching the I/O or instrument list
✅ Overcrowded layouts and poor line routing
✅ Redlines not completely incorporated
✅ Missing final QA/QC before issue

Small drafting errors can create significant confusion later during programming, construction, and commissioning.

What P&ID mistake do you encounter most often?