Seek advice on the classification, differences, and requirements of process flow diagrams
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I would like to ask everyone: strictly speaking (or according to the standards of established design institutes), 1. How many types are there for process flow diagrams in the process engineering field? 2. What is the difference between them? 3. What requirements do each need to meet? 4. What is commonly referred to as a “process flow diagram” – is it the PFD, a process flow diagram with control points, or PID? Also, I was wondering if it would be possible to share the standard and requirement documents from design institutes and design firms? Thank you!
PFD is the initial stage; as the design progresses and reaches the level of construction drawings, what results is PID. Your fourth point is correct. The main difference between PFD and PID lies in the level of detail: PFD includes only the primary instruments and valves, while PID encompasses all control instruments and valves.
The PFD shows the main processes; many auxiliary processes need not be depicted. Within the main processes, for example, a control valve is represented simply as such, without the need to draw a detailed diagram of the entire control valve assembly. PFD is primarily used to express material balance and heat balance. PID is a very detailed, extremely detailed process flow; not a single pipeline or valve can be omitted.
Strictly speaking, PFD and PID are finished documents belonging to different fields of expertise； PFD is provided by the process engineering team, while PID is provided by the systems engineering team. The level of detail for both is continuously improved as the project progresses through its design phases; PID is not merely a detailed design document based on the PFD. The classification mentioned by the original poster is not very clear; in addition to the common PFD and PID, there are also things like UID (Process Flow Diagram for Utility Pipelines), etc. As for the level of detail required for these design documents at different stages of design, reference can be made to GB/T 50933-2013, the Standard for Preparation of Design Documents for Petrochemical Plants.
What was said upstairs is quite detailed; it would be better for the original poster to first take a look at the design manuals or specifications to gain a basic understanding.