P&ID Diagram : Process Vs. Piping

Technical

Whats ‘P’ Stands for!

In office someone told me, lets not spend (tone was ‘waste’) time in making P&ID, as our machine has no piping! an I was like … confused on matching the description of P&ID with need of P&ID. and hence this article.

I just went back to basis, and tried to find out whats the ‘dictionary’ meaning first.


  • ISA 5.4 Says, This standard establishes minimum required information and identifies additional optional information for a loop diagram for an individual instrumentation loop. This loop is typically part of a process depicted on the class of engineering drawings referred to as Piping and Instrument Drawings (P&IDs).
  • EN ISO 1068 Says,  a piping and instrument diagram (P & ID)
  • Document on ISA Website , refer The process and instrumentation diagram (“P&ID” as it often called) represents a document that can take on many different forms . 


  • IS 3232: Says, RECOMMENDATIONS‘ ON GRAPHICAL SYMBOLS FOR PROCESS FLOW DIAGRAMS, PIPING AND INSTRUMENTATION DIAGRAMS
  • South Austria Water Technical Standard TS 112 : Process and Instrumentation Diagrams (P&ID)

So, is it Piping of Process diagram? What we understand?


The challenge, limiting it to piping application, user can ignore its advantage  on discrete machines, where there is no piping (or less of it), but its highly automated.  

To answer this question, we need to see what the diagram help us with.

It help us with
  • Understanding the design philosophy.
  • Understanding of process flow (energy and mass flow)
  • Process Control parameter, loops, interlocks
  • Economics of system, process optimization
  • HAZOP Study
  • Unit operation, interlinking between plants and machines. 

It will be more appropriate to consider P&ID and Process & Instrument Diagram, which shows following but not limited. 

  • Material & Energy Flow
  • Interconnecting Piping 
  • Stations of operations
  • Instruments
  • Interlocks and data flow
  • Loops and control logic
Let me know your views on this.