Butterfly valve P&ID symbol: Complete Engineering Guide
Understanding butterfly valve symbols on P&ID diagrams is essential. It helps EPC contractors, engineers, and procurement teams work together smoothly. This guide covers standard symbols for manual, gear, pneumatic, electric, and hydraulic valves. It also covers wafer, lug, and double flanged types per ISO 10628, ISA S5.1, and ASME Y32.2.
Butterfly valve schematic symbol: Industrial Valve Guide
KELOR (Krishna Industries) sources industrial butterfly valves from verified manufacturers. We supply bulk B2B orders across India and global markets.
- Body Types: Wafer, Lug, Double Flanged
- Materials: Cast Iron (CI), Ductile Iron (DI), SS304, SS316
- Actuation: Manual, Pneumatic, Electric, Hydraulic
- Size Range: 40mm (1.5″) to 600mm (24″) and above
- Standards: ISO 10628, ISA S5.1, ASME Y32.2 symbol compliance
MOQ: Negotiable for bulk orders | GST: Registered | Dispatch: Pan India & Export | Mill Test Report 3.1 available on request
A butterfly valve is a quarter-turn valve. It regulates, isolates, and controls flow in a pipeline. It has a circular disc mounted on a rotating shaft. Turning the disc parallel to the flow opens the valve. Turning it perpendicular closes the flow path.
Compact & Lightweight
Butterfly valves are lighter and smaller than gate or ball valves. This makes them ideal for tight spaces.
Fast Quarter-Turn Operation
A 90-degree rotation provides quick open/close action. This improves emergency shutdown response times.
Low Pressure Drop
The disc profile creates minimal obstruction. This results in lower pressure drop compared to other valve types.
Cost-Effective
Lower initial cost, reduced weight, and simpler actuator needs make them a budget-friendly choice for large pipes.
Easy Maintenance
Inline replaceable seats and fewer moving parts make field maintenance quick and inexpensive.
Throttling Capability
High-performance butterfly valves with offset discs are great for adjusting flow in water treatment and HVAC systems.
Valve symbols are standard graphics used in engineering drawings. They show different valve types and their functions. These symbols act as a universal language. They help engineers, contractors, and procurement teams share valve specs clearly. This prevents confusion on global projects.
Document Types Using Valve Symbols
P&ID (Piping & Instrumentation Diagram)
The main document showing all valves, instruments, and piping connections in a process system.
PFD (Process Flow Diagram)
A simplified block diagram showing major equipment and valves. It indicates isolation and control points.
Piping Isometric Drawings
3D piping representations. Valve symbols help installers find the correct valve type and location.
Plant Layout Drawings
Top-view equipment arrangements. Valve symbols show positions for structural planning and access.
What Valve Symbols Identify
✅ Valve Type
The shape identifies if it is a butterfly, gate, ball, globe, or check valve.
✅ Operation Method
Actuator symbols (handwheel, gear, pneumatic, electric) show how the valve operates.
✅ Flow Direction
Arrows or symbol orientation indicate the intended flow direction through the pipe.
✅ Actuation Type
Extra symbols show if the valve is manual, pneumatic, electric, or hydraulic.
✅ Fail-Safe Position
Annotations show if the valve fails open (FO), fails closed (FC), or fails in last position (FL).
✅ Control Function
Tag numbers identify if the valve is part of a control loop or used for simple isolation.
📌 ISO 10628 / ISA S5.1 Standard Symbol:
The basic butterfly valve symbol on a P&ID diagram looks like a bowtie. It sits on a straight pipeline. The triangles represent the valve body. The line between them represents the rotating disc.
- Two triangles (bowtie): Represent the valve body and disc assembly.
- Pipeline connection: Straight lines show the piping entering and exiting.
- Shaft orientation: A small perpendicular line shows the disc shaft.
- No actuator symbol: Shows a basic manually operated butterfly valve.
- Tag number: An ID (e.g., BV-101) is placed nearby for the Bill of Materials.
⚠️ Important Note: The basic bowtie symbol is standard. However, rendering can vary slightly between EPC companies. Always check the project-specific P&ID legend for exact rules.
On P&ID diagrams, butterfly valve symbols differ by actuation method. The basic bowtie stays the same. Extra symbols are added to show how the valve operates.
🔮 Manual Butterfly Valve Symbol
The most basic representation. No extra actuator symbol is shown.
- Basic bowtie symbol along the pipeline.
- Operation: Hand lever or handle (90-degree turn).
- Used for isolation in non-frequent operation lines.
- Tag example: BV-101, XV-201 (on-off valve).
⚙ Gear Operated Butterfly Valve Symbol
A gear symbol is attached to the basic butterfly valve symbol.
- Basic bowtie with a gear symbol on top.
- Gear symbol shown as two interlocking circles.
- Operation: Handwheel through gear reducer.
- Used where higher torque is needed for large valves.
Actuated symbols include an actuator graphic attached to the basic bowtie. This shows how the valve is automatically or remotely operated.
🌀 Pneumatic Actuated Butterfly Valve Symbol
A pneumatic actuator symbol (diaphragm or cylinder) is attached to the valve.
- Diaphragm actuator shown as a rounded rectangle or semicircle.
- Cylinder actuator shown as a rectangular box with a piston.
- Fail-safe position noted: FO (Fail Open) or FC (Fail Close).
- Application: Process control loops and automated isolation.
⚡ Electric Actuated Butterfly Valve Symbol
An electric motor actuator symbol (M inside a box) is attached to the valve.
- Motor symbol: Letter “M” enclosed in a rectangular box.
- Can include positioner or limit switch annotations.
- Fail-safe position noted: FO, FC, or FL (Fail Last).
- Application: Remote operation and DCS/SCADA controlled service.
🚗 Hydraulic Actuated Butterfly Valve Symbol
A hydraulic actuator symbol indicates fluid-power control for heavy-duty use.
- Hydraulic cylinder shown as a rectangular box with a piston rod.
- Higher torque output compared to pneumatic actuators.
- Fail-safe position noted: FO or FC (spring return or accumulator).
- Common in oil & gas, power plants, and heavy industry.
Specifying “Wafer” Body Type? Don’t Forget the NRV.
If your P&ID specifies Wafer Type Butterfly Valves for isolation, the same pump discharge lines typically require Wafer Check Valves (NRV) to prevent backflow. Both use the identical “wafer” installation method. This saves space, weight, and bolt costs in your pipe rack layout.
View API 594 Wafer Check Valve Specs & Pricing →The basic bowtie represents the valve generically. Extra markings on P&ID drawings show the body type. This helps procurement teams prepare accurate Bills of Materials (BOM).
🔨 Wafer Type Butterfly Valve Symbol
Installed between two pipe flanges using through-bolts. The symbol shows no flange markings on the valve body.
- Basic bowtie symbol between two pipeline flanges.
- Held in place by pipeline flange bolts.
- Most common and economical body type.
- Not designed for dead-end service.
- System Pairing: Often installed alongside Wafer Check Valves (NRV) on pump discharge lines.
🔧 Lug Type Butterfly Valve Symbol
Has threaded lugs (tabs) on both sides for bolted connection. Threaded lug indicators are shown on the symbol.
- Basic bowtie with lug/tab markings on both sides.
- Each side has its own bolt holes.
- Can be used for dead-end service.
- Common in water treatment and HVAC fire protection.
🛡 Double Flanged Butterfly Valve Symbol
Has integral flanges on both ends. Flange markings are shown on both sides of the symbol.
- Basic bowtie with flange markings on both ends.
- Integral flanges match standard ratings (PN 10, PN 16, Class 150).
- Bolted connection offers the highest structural integrity.
- Common in oil & gas, petrochemical, and power generation.
P&ID diagrams may show the disc’s default or fail-safe position. This is vital for safety-critical applications.
🔴 Normally Closed (NC) / Fail Closed (FC)
The disc is shown in the perpendicular (closed) position by default. When power is lost, the valve closes automatically. This protects downstream equipment.
🟢 Normally Open (NO) / Fail Open (FO)
The disc is shown in the parallel (open) position by default. When supply fails, the valve opens. This ensures continuous flow for cooling or safety systems.
🟠 Modulating / Throttling Control
The valve is shown with an actuator and positioner symbol. This indicates it can adjust flow, pressure, or temperature at any point between fully open and closed.
Butterfly valve symbols are governed by global standards. These ensure clarity and universal understanding across engineering teams worldwide.
🌐 ISO 10628
International standard for flow diagrams. It specifies graphical symbols for piping, equipment, and valves. Widely used in global EPC projects.
🎯 ISA S5.1
Instrumentation Symbols and Identification standard. It defines symbols for process measurement and control instruments on P&ID diagrams.
🏫 ASME Y32.2
Graphic Symbols for Pipe Fittings, Valves, and Piping. It provides standard representations used in North American projects.
🇩🇪 DIN Standards
German Institute for Standardization guidelines. Commonly used in European engineering projects for process drawings.
🌎 KELOR Compliance Note: KELOR sources valves from verified manufacturers. Their products comply with international standards like ISO 10628, ISA S5.1, and ASME Y32.2. We provide the technical details and spec sheets that EPC contractors and procurement teams need.
Butterfly valves are highly versatile. They are used across many industries due to their compact design, fast operation, and low cost.
💧 Water & Wastewater Treatment
Used in treatment plants, sewage systems, and distribution networks for isolation and flow control in large pipes.
💨 Oil & Gas
Used in crude oil pipelines, natural gas distribution, and refinery lines. Double flanged types are common for higher pressure.
⚡ Power Generation
Cooling water systems, circulating water lines, and auxiliary piping in thermal, hydro, and nuclear plants rely on them.
🏩 Chemical & Petrochemical
Processing plants use SS304/SS316 butterfly valves with compatible seats for corrosive media handling.
🌳 HVAC & Fire Protection
Heating, ventilation, and fire protection networks use wafer and lug types for chilled water and fire fighting lines.
🍴 Food & Beverage
Sanitary butterfly valves with FDA-compliant seats and SS316 construction are used for hygienic flow control.
For B2B buyers and project managers, understanding these symbols is a must. It is a key skill. It directly impacts project accuracy, cost savings, and safety.
✅ Correct Valve Selection
Understanding symbols ensures you order the right valve type and actuation method as specified in the drawings.
✅ Accurate Bill of Materials (BOQ)
Valve symbols feed directly into the BOQ. Misinterpreting a symbol can lead to wrong specs, costly returns, and delays.
✅ Reduced Installation Errors
Field teams rely on P&ID symbols to identify valve type and orientation. Clear understanding prevents wrong installations.
✅ Compliance with Tender Specs
Tender documents reference P&ID symbols. Understanding them ensures your procurement matches the exact technical requirements.
About KELOR — Butterfly Valve Supplier from Ahmedabad, India
KELOR (Krishna Industries) sources industrial butterfly valves from verified manufacturers. Our products comply with ISO 10628, ISA S5.1, and ASME Y32.2 symbol standards. Every supplier is vetted for quality and testing compliance. We provide the technical details and spec sheets that EPC contractors and procurement teams need.
- Verified source model: Every valve sourced from vetted, quality-certified manufacturers.
- Wide range: Wafer, lug, and double flanged types in CI, DI, SS304, and SS316.
- Actuation options: Manual, pneumatic, electric, and hydraulic actuation.
- Documentation: Mill Test Report 3.1 available on request.
- GST registered, Pan India dispatch, since 2017. We are a leading supplier of industrial butterfly valves.
Need Butterfly Valve Symbols Documentation for Your Project?
KELOR provides technical details, spec sheets, and symbol reference docs for all butterfly valve types. Contact us for project-specific requirements.
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KELOR Krishna Industries — Industrial Butterfly Valve Supplier India
India’s leading supplier of industrial butterfly valves — wafer, lug, and double flanged types sourced from verified manufacturers. Bulk B2B supply and exports across India and international markets since 2017.