A valve symbol legend gives designers, drafters, reviewers, and contractors a shared visual reference for reading and producing piping and instrumentation diagrams. This Valve Symbols Legend CAD resource focuses on commonly encountered valve symbols and variations for P&ID work, piping schematics, and coordination drawings.
Use the DWG reference alongside your project drawing standards, line lists, equipment information, and piping details. For related drafting work, compare the valve symbols with your pipe dimensions and schedules, piping fittings, and flange reference resources so the graphic symbol and connected piping information remain consistent.
This Valve Symbols Legend CAD sheet helps you create clear, consistent P&ID and piping schematics. It includes common valve types and typical symbol variations used in engineering drawings—useful for design, shop drawings, and coordination.
Symbols included in this legend
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Ball valve (open / close)
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Gate valve (open / closed) + gate valve (parallel slide)
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Globe valve (open / close) + standard globe valve
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Plug valve
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Butterfly valve
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Check valve (standard + variations such as piston type and disc type)
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Angle valve, three-way valve, needle valve
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Choke valve (fixed / adjustable)
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4-way flanged valve
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Foot valve with strainer
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Pressure reducing valve (PRV), pressure/vacuum valve
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Relief valve
Why it’s useful
A consistent valve symbol legend reduces drawing mistakes and makes your P&ID easier to read for reviewers, contractors, and operators.
How to use this valve symbol reference
Start by identifying the valve function shown on the drawing, then compare the symbol with the project legend and any notes governing actuation, flow direction, or control. The CAD sheet is most useful during P&ID layout, design review, shop-drawing preparation, and coordination between engineering disciplines.
What the symbol groups communicate
- Isolation and flow-control symbols: Ball, gate, globe, plug, butterfly, angle, needle, and choke valve symbols help distinguish commonly used valve arrangements.
- Flow-direction and protection symbols: Check valves, foot valves with strainers, relief valves, and pressure-related valves identify functions that should be reviewed against the process design.
- Special arrangements: Three-way valves, four-way flanged valves, and the listed gate, globe, and check valve variations help preserve the intended configuration in a schematic.
Drafting and review considerations
Keep the symbol legible at the drawing scale, align it with the connected process line, and apply the project tag and annotation conventions consistently. A symbol alone does not establish the valve’s material, end connection, pressure class, actuator, control philosophy, or installation requirement. Confirm those details in the applicable project documents before procurement, fabrication, or field installation.
Because valve conventions can vary between companies and disciplines, treat this sheet as a practical CAD reference rather than a replacement for the governing project legend. The downloadable DWG can support a controlled block library, but any reused block should be checked for layer, text, lineweight, and title-block requirements.
Valve symbols legend CAD FAQ
What valve types are included in this CAD legend?
The legend includes ball, gate, globe, plug, butterfly, check, angle, three-way, needle, choke, four-way flanged, foot valve with strainer, pressure reducing, pressure/vacuum, and relief valve symbols. It also shows identified variations for several valve types.
Can this DWG be used for a P&ID?
Yes. The sheet is intended to support clear, consistent P&ID and piping schematics. Before issuing a drawing, compare the symbols with the project’s approved legend and drafting requirements.
Does a valve symbol specify the complete valve selection?
No. A graphic symbol communicates the represented valve type or function, but selection and installation details must be confirmed from the project specifications, equipment data, piping requirements, and applicable engineering review.
Why should a project use a consistent valve legend?
Consistent symbols reduce interpretation errors and make drawings easier for reviewers, contractors, operators, and other project participants to read. They also help maintain a uniform CAD block library across related drawings.