The Complete Guide to P&ID Control Valve Symbols
130+ valve symbol combinations covering 9 valve types, 13 actuator variations, check valves, relief valves, and more. ISA 5.1 / ANSI compliant. Print-ready.
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Get our print-ready PDF with every control valve symbol used in piping and instrumentation diagrams. Perfect for your shop floor, office, or field reference.
- 9 valve types × 13 actuator variations
- Check valve, relief valve & special valve symbols
- Actuator symbol legend with descriptions
- ISA 5.1 / ANSI standard compliant
- Print-ready portrait format (8.5" × 11")
Why P&ID Symbols Matter
Piping and Instrumentation Diagrams are the universal language of process engineering. Whether you're specifying valves for a new plant or troubleshooting an existing system, knowing these symbols lets you communicate clearly with engineers, contractors, and suppliers.
What is a Piping and Instrumentation Diagram (P&ID)?
A Piping and Instrumentation Diagram (P&ID) is a detailed technical drawing that shows the piping, equipment, and instrumentation in a process system. Engineers use P&IDs to design, build, and maintain industrial facilities across oil and gas, chemical processing, water treatment, power generation, and manufacturing.
Every valve on a P&ID is represented by a standardized symbol defined by the ANSI/ISA-5.1 standard. Understanding these symbols is essential for engineers specifying equipment, procurement teams ordering valves, and operations personnel maintaining facilities.
Common Control Valve Types and Their P&ID Symbols
Control valve symbols consist of a body shape (indicating valve type) and an actuator symbol (indicating how the valve is operated). The base shape for most valves is two opposing triangles meeting at a point — often called a "bowtie" shape. The center detail differentiates each valve type.
Gate Valve
Full-bore isolation valve shown with a vertical line at the center of the bowtie. Used for on/off service where minimal pressure drop is needed when fully open. Common in water systems, oil and gas pipelines, and general industrial service.
Globe Valve
Throttling valve shown with a filled circle at the center. The plug-and-seat mechanism provides excellent flow regulation. Preferred for applications requiring precise flow control, such as cooling water systems and fuel oil lines.
Ball Valve
Quarter-turn valve shown with a filled diamond at the center. Offers tight sealing, low torque, and fast shutoff. Widely used in natural gas, petroleum, and chemical processing applications.
Plug Valve
Quarter-turn valve shown with a filled rectangle at the center. Uses a cylindrical or tapered plug to control flow. Ideal for multi-port configurations and applications requiring frequent operation.
Butterfly Valve
Rotating disc valve shown with a circle bisected by a diagonal line representing the disc. Compact design makes it ideal for large pipe sizes. Used in HVAC, water distribution, and chemical processing.
Diaphragm Valve
Shown with an arc or dome shape at the center. A flexible diaphragm seals the flow path, making it ideal for corrosive, sterile, and ultra-pure applications in pharmaceutical and food processing.
Needle Valve
Fine-adjustment valve shown with a narrow pointed triangle. The tapered pin provides precision flow control for instrumentation, sampling systems, and metering applications.
Check Valve
Non-return valve shown with one filled triangle and one open triangle separated by a vertical line. Prevents backflow in piping systems. Available in swing, lift, tilting disc, and spring-loaded configurations.
Pinch Valve
Shown with curved pinch lines at the center. Compresses a flexible tube to regulate flow. Excellent for handling slurries, abrasive media, and materials that would damage conventional valve internals.
Knife Gate Valve
Shown with a thick vertical line with blade indicator. Sharp-edged gate cuts through solids and fibrous materials. Essential in pulp and paper, mining, and wastewater treatment applications.
Valve Actuator Symbols
The actuator symbol sits atop the valve body, connected by a stem line. Each actuator type has a distinct symbol that tells engineers exactly how the valve is operated. Our PDF reference guide shows all 13 actuator types applied to each valve body.
| Actuator Type | Symbol | Visual | Application |
|---|---|---|---|
| Hand Operated | T-bar / handwheel | Manual on-site operation | |
| Pneumatic (Diaphragm) | Filled triangle | Most common process control actuator | |
| Pneumatic (Piston) | Open triangle | Higher force than diaphragm | |
| Motor Operated | Circle with "M" | Large valves, remote operation | |
| Hydraulic | Rectangle with "H" | Very high force applications | |
| Solenoid | Diamond with "S" | Fast on/off electromagnetic switching | |
| Balanced Diaphragm | Opposing triangles (hourglass) | Minimizes process pressure effects | |
| Electric | Circle with "E" | Electric quarter-turn and linear | |
| Digital / Modulating | Circle with "D" | Microprocessor-controlled positioning | |
| Pilot Operated | Circle with "P" + dashed line | Pilot-controlled safety systems | |
| Pneumatic Rotary | Filled triangle with arc | Quarter-turn ball and butterfly valves | |
| Electro-Hydraulic | Rectangle with "E/H" | Combined electric + hydraulic power | |
| Gear Operated | Circle with "G" | Gear reduction for high-torque needs |
How to Read Valve Symbols on a P&ID
- Identify the valve body shape — The bowtie base tells you it's a valve. The center detail tells you the type (vertical line = gate, filled circle = globe, filled diamond = ball, circle with diagonal = butterfly, etc.).
- Check the actuator symbol — Look above the valve body for the actuator indicator. This tells you how the valve is operated (pneumatic, motor, manual, etc.).
- Read the failure position — Arrows indicate fail-safe behavior: arrow toward valve = Fail Closed (FC), arrow away = Fail Open (FO), no arrow = Fail in Last position (FL).
- Check the notation below — Size, pressure class, face type, and connection. Example:
2" 300 RF FLGmeans 2-inch, ANSI 300 class, raised face, flanged. - Follow the line types — Solid lines = process piping, dashed lines = signal/control lines, double lines = jacketed piping.
Get All 130+ Symbols in One Printable PDF
Download the free ValveMan P&ID Valve Symbols Reference Guide — print it, pin it up, and never second-guess a valve symbol again.
Download Free PDFSpecial Valve Types on P&ID Drawings
Beyond standard control valves, P&IDs include several specialized valve types:
- Relief/Safety Valves — Protect equipment from overpressure. Shown with an angled body and spring symbol. Types include pressure relief, safety valve (pop-action), pressure/vacuum relief, pilot operated relief, and rupture disc.
- 3-Way and 4-Way Valves — Multi-port configurations for flow diversion or mixing. Used in heat exchangers, bypass systems, and sampling.
- Control Valves (Generic) — Automated process control valves with positioners and transmitters.
- Pressure Reducing Valves — Maintain downstream pressure at a set level regardless of upstream fluctuations.
- Float Valves — Level-controlled operation for tank filling and overflow prevention.
- Foot Valves — Check valves installed at the suction end of a pump to maintain prime.
Why ValveMan for Your Industrial Valve Needs
Since 1965, ValveMan has been the smartest way to buy valves. We carry a comprehensive inventory of gate, globe, ball, check, butterfly, and specialty valves from trusted manufacturers. Whether you're sourcing valves for a new project or replacing equipment in the field, our team of valve experts is here to help.
Frequently Asked Questions
What do the symbols on a P&ID mean?
P&ID symbols represent the physical equipment in a process system. Valve symbols use standardized shapes defined by ANSI/ISA-5.1 to indicate valve type (gate, globe, ball, etc.) and actuation method (pneumatic, electric, manual, etc.). The symbols allow engineers, operators, and procurement teams to understand the system design without ambiguity.
How many types of valve symbols are there on a P&ID?
There are 9 primary valve body types (gate, globe, ball, plug, butterfly, diaphragm, needle, pinch, and knife), each of which can be combined with 13 different actuator types. Additionally, there are specialized symbols for check valves, relief/safety valves, 3-way and 4-way valves, and other configurations — totaling over 130 unique symbol combinations.
What is the difference between a gate valve and globe valve symbol?
Both use the "bowtie" base shape (two opposing triangles), but the center detail differs. A gate valve has a vertical line at the center, representing the sliding gate mechanism. A globe valve has a filled circle at the center, representing the plug-and-seat throttling mechanism. Gate valves are for on/off isolation; globe valves are for flow regulation.
What does the actuator symbol on a P&ID tell you?
The actuator symbol sits atop the valve body and indicates how the valve is operated. A filled triangle means pneumatic diaphragm, an open triangle means pneumatic piston, a circle with "M" means motor operated, a diamond means solenoid, and so on. This information is critical for ordering the correct valve assembly and understanding the control system design.
Where can I download a P&ID valve symbols chart?
ValveMan offers a free, print-ready P&ID Valve Symbols Reference Guide that covers 130+ symbol combinations including all major valve types with every actuator variation, check valves, relief valves, and special valve configurations. Enter your email at the top of this page to download the guide instantly.
What standard defines P&ID valve symbols?
The primary standard is ANSI/ISA-5.1 (Instrumentation Symbols and Identification), maintained by the International Society of Automation (ISA). This standard is widely used in North America and the global oil and gas industry. In Europe and international projects, ISO 14617 is also common. While there can be minor variations between companies, the core symbols shown in standard references are universally recognized.
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