Process Plant Schematics: A Key to Understanding

What is a key document that process plant schematics are typically referenced to?

a. Wiring diagram
b. Vendor manual
c. P&ID
d. Instrument index

Answer:

Schematics are typically referenced to the P&ID, which provides detailed information about the plant's systems, differing from wiring diagrams, vendor manuals, or the instrument index.

A schematic will most always be referenced to the P&ID (Piping and Instrumentation Diagram). The P&ID provides a detailed representation of the piping, instruments, and systems of a process plant and is used as a blueprint for construction and a guide for maintenance and modification.

A schematic differs from a wiring diagram in that it provides a more abstract representation of an electrical system without focusing on physical layout. While a vendor manual may provide specifics on components supplied by external vendors, it is not typically the primary reference point for an overall schematic.

Similarly, the instrument index is a comprehensive list of all instruments in the facility, which doesn't offer the detailed connection and system view that a schematic tied to a P&ID does. Schematics take into account the shapes and dimensions of all physical components, knowledge of which components are externally sourced or internally fabricated, and the related materials and fabrication processes, as well as the detailed schematic diagram of electrical subsystems and any computer code for embedded systems.