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How to read piping drawings

  1. Sep 22, 2011 #1
    Dear all...

    Pls advise me how to read and understand piping drawings (process PID drawings)... I mean how does fluid flow and what process are running there. I am doing physics and I have quite good technical background. When interpreting electrical circuits we are having nodes with defind voltage and ground... so we know that current flows from higher potential to lower...is there similar approach to piping scheme... any books for beginner or quick manuals please...

    Thank you very much
  2. jcsd
  3. Sep 22, 2011 #2


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    Gold Member

    P&ID drawings don't typically (not that I've ever seen) give actual process information. The lines are typically drawn with arrows showing the direction of flow in P&IDs, but certainly in the proprietary Process Flow Diagrams. The arrows should be built into the lines, so look like a triangle overlayed onto the line itself, with one vertex directly on the line and pointing in the direction of flow.

    Pressure is what would dictate the direction of flow and the analogy between pressure and voltage is commonly (for good or bad) used, although that's because pressure and differential pressure are more easily understood than voltage.

    If the lines don't have arrows for indication, you'll have to get the information indirectly. The way lines are drawn for pumps is usually a clear indication of the direction of flow. Sometimes there is special instrumentation (shutdowns, interlocks, etc.) that will give away process limitations that could allow you to determine a little about the process.

    There are other types of equipment that are directionally specific (like a check valve) and are drawn that way. Learning these types of equipment would also be an easy way.

    Other than that, without any specific drawings or examples it could be hard to explain.
  4. Sep 23, 2011 #3
    P&IDs are just that - schematic representations of the piping and instruments - the installed hardware. They do not show the process parameters (flow, temperature, pressure, etc.) because those parameters will vary depending on how the system is operated.
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