Use this General Process Symbols Legend CAD reference when preparing or reviewing process and instrumentation diagrams for industrial facilities. The DWG resource brings common equipment and process-unit symbols together so designers, drafters, and reviewers can work from a consistent visual reference.
This resource is especially useful alongside P&ID terminology guides, piping references, and CAD block libraries. It supports drawing coordination, but project-specific drafting conventions and approved symbol libraries should always take precedence.
This General Process Symbols Legend CAD sheet is a quick reference for P&ID and process plant drawings. It includes commonly used symbols for towers, reactors, furnaces, and major process units, helping you standardize diagrams and improve readability across projects.
The legend typically includes:
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Tower and cooling equipment symbols (crossflow/induced draft, counterflow/forced draft, chimney tower)
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Plate tower and packed tower icons
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Reactor and unit symbols such as fluidized reactor and other process vessels
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Major process unit references (as shown) like:
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Fluid Catalytic Cracking (FCC)
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Fluid Coking
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Hydrocracking
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Hydrodesulfurization (HDS)
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Alkylation
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Utility/plant items like tubular equipment, screens, transport/loader icons, and motor references
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Furnace symbols (multiple styles shown on the sheet)
Use this CAD legend for:
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P&ID documentation sets for oil & gas and industrial plants
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Standard templates for process engineering teams
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Training and QA reviews to keep symbols consistent
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Faster drafting with a ready-to-use symbol reference sheet
What this process symbol legend covers
The reference sheet groups symbols by the type of equipment or plant function they represent. This makes it easier to locate a suitable graphic during initial layout work, drawing updates, or a quality review.
- Towers and cooling equipment: Review symbols for crossflow and induced-draft arrangements, counterflow and forced-draft arrangements, and chimney tower representations.
- Separation and contacting equipment: Identify plate tower and packed tower icons when documenting process equipment.
- Reactors and vessels: Use the reactor and process-vessel symbols as a visual reference, including the fluidized reactor representation.
- Major process units: Find references for Fluid Catalytic Cracking, Fluid Coking, Hydrocracking, Hydrodesulfurization, and Alkylation.
- Plant and utility items: Check symbols for tubular equipment, screens, transport or loader equipment, and motors.
- Furnaces: Compare the furnace styles shown on the sheet before selecting a symbol for a drawing.
Using the DWG reference in drafting workflows
Use the legend during P&ID preparation, template development, drawing review, and team training. Before issuing a drawing, check that equipment symbols, tags, linework, and annotations follow the project drafting guide and remain understandable when the drawing is printed or exchanged between teams.
A symbol identifies equipment graphically; it does not by itself define process duty, mechanical design, operating conditions, or connection details. Coordinate the selected symbol with the equipment list, process documentation, piping layouts, and approved project standards.
Practical review checklist
- Confirm that the symbol matches the equipment description used in the project documentation.
- Check that similar equipment is represented consistently throughout the drawing set.
- Verify that symbols remain legible at the intended drawing scale.
- Review the drawing against the project legend before completing a QA check.
- Keep the CAD file organized so approved blocks can be reused without introducing conflicting graphics.
Frequently asked questions
What is included in this General Process Symbols Legend CAD file?
The reference includes symbols for towers, cooling equipment, plate and packed towers, reactors, process vessels, major process units, utility and plant items, motors, and furnaces.
Who can use this P&ID symbol reference?
Process engineers, piping designers, CAD drafters, project reviewers, and engineering students can use it as a visual drafting reference for process plant drawings.
Does the CAD legend replace a project drafting standard?
No. Use the file as a convenient reference, then follow the approved project, client, or company symbol conventions for issued drawings.
Can these symbols be used to define equipment design requirements?
No. A process symbol communicates equipment identity or function at the drawing level. Equipment specifications, process conditions, piping connections, and mechanical requirements must come from the applicable project documents and engineering checks.
Where is this reference most useful?
It is useful for P&ID documentation, process engineering templates, training, QA reviews, and faster drafting of oil and gas or industrial plant drawings.