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P&ID Symbol Guide — 2026
Butterfly Valve Symbols — Complete P&ID Guide for Engineering Drawings | KELOR
Understanding butterfly valve symbols on P&ID diagrams is essential for EPC contractors, process engineers, piping designers, and plant procurement teams. This comprehensive guide covers standard butterfly valve symbols including manual, gear operated, pneumatic, electric, and hydraulic actuated types — along with body type variations for wafer, lug, and double flanged configurations as per ISO 10628, ISA S5.1, and ASME Y32.2 international standards.
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Symbol Types Covered
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Actuation Methods
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Body Type Symbols
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Industries Served
📦 Industrial Butterfly Valves — Product Summary
KELOR (Krishna Industries) sources a comprehensive range of industrial butterfly valves from verified manufacturers for bulk B2B supply across India and international markets.
- Body Types: Wafer Type, Lug Type, Double Flanged
- Materials: Cast Iron (CI), Ductile Iron (DI), Stainless Steel 304 (SS304), Stainless Steel 316 (SS316)
- Actuation: Manual (Hand Lever), Pneumatic, Electric (Motorized), Hydraulic
- Size Range: 40mm (1.5″) to 600mm (24″) and above
- Pressure Class: PN 10, PN 16, Class 150
- Standards: ISO 10628, ISA S5.1, ASME Y32.2 symbol compliance
MOQ: Negotiable for bulk & project orders | GST: Registered | Dispatch: Pan India & Export | Mill Test Report 3.1 can be provided on request
What Is a Butterfly Valve?
A butterfly valve is a quarter-turn rotational valve used to regulate, isolate, and control flow in a pipeline. It consists of a circular disc (the “butterfly”) mounted on a rotating shaft. When the disc is turned parallel to the flow, the valve is fully open; when turned perpendicular, it creates a seal against the valve seat, fully closing the flow path.
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Compact & Lightweight
Butterfly valves are significantly lighter and more compact than gate, globe, or ball valves of the same size, making them ideal for space-constrained installations.
⚡
Fast Quarter-Turn Operation
90-degree rotation provides quick open/close operation, reducing actuation time and improving emergency shutdown response in critical process lines.
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Low Pressure Drop
The disc profile through the flow path creates minimal obstruction, resulting in lower pressure drop compared to many other valve types.
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Cost-Effective
Lower initial cost, reduced installation weight, simpler actuator requirements, and less maintenance make butterfly valves a cost-efficient solution for large-diameter applications.
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Easy Maintenance
Inline replaceable seats, fewer moving parts, and straightforward disc access make field maintenance quicker and less expensive.
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Throttling Capability
High-performance butterfly valves with offset disc designs are suitable for modulating and throttling service in water treatment, HVAC, and process industries.
Valve symbols are standardized graphical representations used in engineering drawings to depict different types of valves, their actuation methods, and their function within a piping system. These symbols serve as a universal language that allows design engineers, EPC contractors, piping designers, procurement teams, and field technicians to communicate valve specifications without ambiguity across international project teams.
Document Types Where Valve Symbols Are Used
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P&ID (Piping & Instrumentation Diagram)
The primary engineering document where butterfly valve symbols appear — showing all valves, instruments, and piping connections in a process system.
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PFD (Process Flow Diagram)
Simplified block diagram showing major process equipment and valves — butterfly valve symbols indicate isolation and control points in the process flow.
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Piping Isometric Drawings
3D representation of piping systems where valve symbols help installers identify correct valve type, orientation, and location during construction.
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Plant Layout Drawings
Top-view arrangement of equipment and piping where valve symbols indicate valve positions for structural planning and access clearance.
What Valve Symbols Identify
✅ Valve Type
The symbol shape identifies whether it is a butterfly valve, gate valve, ball valve, globe valve, check valve, or other type.
✅ Operation Method
Actuator symbols (handwheel, gear, pneumatic, electric, hydraulic) indicate how the valve is operated.
✅ Flow Direction
Arrows or orientation of the symbol indicate the intended flow direction through the pipeline.
✅ Actuation Type
Additional symbols attached to the valve body indicate whether it is manual, pneumatic, electric, or hydraulic actuated.
✅ Fail-Safe Position
Symbol annotations indicate whether the valve fails open (FO), fails closed (FC), or fails in last position (FL).
✅ Control Function
Tag numbers and instrument bubble symbols on P&IDs identify whether the valve is part of a control loop or used for isolation.
Standard Butterfly Valve Symbol (Basic Representation)
📌 ISO 10628 / ISA S5.1 Standard Symbol:
The basic butterfly valve symbol on a P&ID diagram consists of two triangular shapes (bowtie configuration) positioned along a straight pipeline. The triangles represent the valve body, and the line between them represents the circular disc or butterfly element that rotates on a shaft to control flow.
- Two triangles (bowtie): Represent the valve body and disc assembly
- Pipeline connection: Straight lines entering and exiting the symbol represent the piping
- Shaft orientation: A small perpendicular line on the symbol indicates the disc shaft — vertical or horizontal
- No additional actuator symbol: When shown without any actuator attachment, it represents a basic manually operated butterfly valve
- Tag number: Alphanumeric identification (e.g., BV-101) is placed near the symbol for reference in the Bill of Materials
⚠️ Important Note: While the basic butterfly valve symbol is standardized (bowtie shape), the specific rendering can vary slightly between different EPC companies and engineering consultants. Always refer to the project-specific P&ID legend/symbol sheet for exact symbol conventions used on a given project.
On P&ID diagrams, butterfly valve symbols are differentiated primarily by their actuation method. The basic bowtie symbol remains the same, but additional symbols are added on top or beside it to indicate how the valve is operated.
Manual Operation
🔮 Manual Butterfly Valve Symbol
The most basic butterfly valve representation on a P&ID — no additional actuator symbol is shown.
- Basic bowtie symbol along the pipeline
- No actuator attachment shown on the symbol
- Operation: Hand lever or handle (90-degree turn)
- Commonly used for isolation in non-frequent operation lines
- Tag example: BV-101, XV-201 (on-off valve)
- Application: Utility lines, cooling water, low-criticality isolation
Gear Operation
⚙ Gear Operated Butterfly Valve Symbol
A gear operator symbol is shown attached to the basic butterfly valve symbol, indicating mechanical gear-assisted operation.
- Basic bowtie symbol with a gear symbol on top
- Gear symbol typically shown as two interlocking circles or a gear wheel
- Operation: Handwheel through gear reducer (multi-turn)
- Used where higher torque is needed for large-diameter valves
- Tag example: BV-102-GO, HV-301
- Application: Large-diameter water lines, HVAC systems, process isolation
Actuated Butterfly Valve Symbols
Actuated butterfly valve symbols include an actuator representation attached to the basic bowtie symbol. The actuator type is indicated by specific graphical symbols that convey how the valve is automatically or remotely operated.
Pneumatic Actuation
🌀 Pneumatic Actuated Butterfly Valve Symbol
A pneumatic actuator symbol (diaphragm or cylinder) is attached to the butterfly valve symbol, indicating air-operated control.
- Basic bowtie symbol with pneumatic actuator on top
- Diaphragm actuator shown as a rounded rectangle or semicircle
- Cylinder actuator shown as a rectangular box with piston
- Supply air connection indicated by “SA” annotation
- Fail-safe position noted: FO (Fail Open) or FC (Fail Close)
- Application: Process control loops, emergency shutdown systems, automated isolation
- Control signal: 3-15 psi (0.2-1.0 bar) or 6-30 psi instrument air
Electric Actuation
⚡ Electric Actuated Butterfly Valve Symbol
An electric motor actuator symbol (M inside a rectangular box) is attached to the butterfly valve symbol, indicating motorized operation.
- Basic bowtie symbol with motor actuator on top
- Motor symbol: Letter “M” enclosed in a rectangular box
- Power supply: Electric (noted on P&ID or datasheet)
- Can include positioner or limit switch annotations
- Fail-safe position noted: FO, FC, or FL (Fail Last)
- Application: Remote operation, DCS/SCADA controlled, modulating service
- Control signal: 4-20 mA or digital bus communication
Hydraulic Actuation
🚗 Hydraulic Actuated Butterfly Valve Symbol
A hydraulic actuator symbol is attached to the butterfly valve symbol, indicating fluid-power operated control for heavy-duty applications.
- Basic bowtie symbol with hydraulic actuator on top
- Hydraulic cylinder shown as a rectangular box with piston rod
- Hydraulic power unit (HPU) supply connection indicated
- Higher torque output compared to pneumatic actuators
- Fail-safe position noted: FO or FC (spring return or accumulator)
- Application: High-pressure pipelines, large-diameter valves, emergency shutdown
- Common in oil & gas, power plants, and heavy industrial applications
While the basic butterfly valve symbol (bowtie) represents the valve generically, additional annotations or markings on P&ID drawings differentiate between body types — wafer, lug, and double flanged. These distinctions are critical for procurement teams when preparing Bill of Materials (BOQ) and placing orders.
Wafer Type
🔨 Wafer Type Butterfly Valve Symbol
Wafer type butterfly valves are installed between two pipe flanges using through-bolts. On P&ID, the symbol is shown without flange markings on the valve body.
- Basic bowtie symbol between two pipeline flanges
- No flange markings on the valve symbol itself
- Held in place by pipeline flange bolts passing through the valve body
- Most common and economical butterfly valve body type
- Not designed for dead-end service (both flanges must be present)
- Lightweight, compact — ideal for large-diameter water and utility lines
Lug Type
🔧 Lug Type Butterfly Valve Symbol
Lug type butterfly valves have threaded lugs (tabs) on both sides for bolted connection to pipeline flanges. On P&ID, threaded lug indicators are shown on the symbol.
- Basic bowtie symbol with lug/tab markings on both sides
- Each side has its own bolt holes — independent flange connection
- Can be used for dead-end service (downstream piping can be removed)
- More expensive than wafer type but offers greater installation flexibility
- Suitable for media that may need periodic line draining or maintenance
- Common in water treatment, chemical, and HVAC fire protection systems
Double Flanged
🛡 Double Flanged Butterfly Valve Symbol
Double flanged butterfly valves have integral flanges on both ends that bolt directly to mating pipeline flanges. On P&ID, flange markings are shown on both sides of the symbol.
- Basic bowtie symbol with flange markings on both ends
- Integral flanges match standard flange ratings (PN 10, PN 16, Class 150)
- Bolted connection — highest structural integrity among body types
- Suitable for higher pressure and critical service applications
- Can be used for dead-end service on either side
- Common in oil & gas, petrochemical, power generation, and water distribution
Butterfly Valve Symbols by Disc Position
Butterfly valve symbols on P&ID diagrams may also indicate the disc’s default or fail-safe position. This is particularly important for control and safety-critical applications where the valve’s behavior during system failure must be clearly defined.
🔴 Normally Closed (NC) / Fail Closed (FC)
The butterfly disc is shown in the perpendicular (closed) position by default. When actuator air or power supply is lost, the valve closes automatically — protecting downstream equipment from uncontrolled flow. Most common fail-safe configuration in process industries.
🟢 Normally Open (NO) / Fail Open (FO)
The butterfly disc is shown in the parallel (open) position by default. When actuator supply fails, the valve opens — ensuring continuous flow for cooling, drainage, or safety relief applications. Common in cooling water and safety systems.
🟠 Modulating / Throttling Control
The valve is shown with an actuator and positioner symbol, indicating it can be positioned at any point between fully open and fully closed. Used in control loops for flow regulation, pressure control, temperature control, and level control applications.
Butterfly valve symbols used in P&ID and engineering drawings are governed by internationally recognized standards. These standards ensure consistency, clarity, and universal understanding across engineering teams, EPC contractors, and procurement professionals worldwide.
🌐 ISO 10628
International standard for flow diagrams for process plants — specifies graphical symbols for piping, process equipment, and valves including butterfly valves. Most widely used in international EPC projects and plant design.
🎯 ISA S5.1
Instrumentation Symbols and Identification standard by the International Society of Automation — defines symbols for process measurement and control instruments, including actuated valve representations on P&ID diagrams.
🏫 ASME Y32.2
Graphic Symbols for Pipe Fittings, Valves, and Piping by the American Society of Mechanical Engineers — provides standardized graphical representations for various valve types including butterfly valves used in North American projects.
🇩🇪 DIN Standards
German Institute for Standardization (DIN) provides additional symbol guidelines commonly used in European engineering projects. DIN 2429 and related standards cover graphical symbols for process engineering drawings.
🌎 KELOR Compliance Note: KELOR sources butterfly valves from verified manufacturers whose products comply with international symbol and engineering standards including ISO 10628, ISA S5.1, and ASME Y32.2. We provide the required technical details, specification sheets, and documentation that EPC contractors, consultants, and plant procurement teams need to accurately specify and procure butterfly valves for their projects.
Common Industries Using Butterfly Valves
Butterfly valves are one of the most versatile valve types, finding application across a wide range of industries due to their compact design, fast operation, and cost-effectiveness — especially in large-diameter piping systems.
💧 Water & Wastewater Treatment
Butterfly valves are extensively used in water treatment plants, sewage systems, desalination plants, and distribution networks for isolation, flow control, and backflow prevention in large-diameter pipelines.
💨 Oil & Gas
Used in crude oil pipelines, natural gas distribution, refinery process lines, and offshore platforms for isolation and control — particularly double flanged types for higher pressure service.
⚡ Power Generation
Cooling water systems, circulating water lines, feedwater systems, and auxiliary piping in thermal, hydro, and nuclear power plants rely on butterfly valves for efficient isolation and modulation.
🏩 Chemical & Petrochemical
Chemical processing plants, petrochemical refineries, and pharmaceutical facilities use SS304/SS316 butterfly valves with compatible seat materials for corrosive and aggressive media handling.
🌳 HVAC & Fire Protection
Heating, ventilation, air conditioning systems and fire protection networks extensively use wafer and lug type butterfly valves for chilled water, hot water, and fire fighting water lines.
🍴 Food & Beverage
Sanitary butterfly valves with FDA-compliant seats and SS316 construction are used in food processing, dairy, brewing, and beverage production for hygienic flow control.
For B2B buyers, EPC procurement teams, and project managers, understanding butterfly valve symbols on P&ID diagrams is not optional — it is a critical professional competency that directly impacts project accuracy, cost efficiency, and operational safety.
✅ Correct Valve Selection
Understanding symbols ensures you order the right valve type (wafer, lug, double flanged) with the correct actuation method (manual, pneumatic, electric, hydraulic) as specified in the engineering drawings.
✅ Accurate Bill of Materials (BOQ)
Valve symbols on P&IDs directly feed into the Bill of Materials. Misinterpreting a symbol can lead to wrong valve specifications, costly returns, and project delays.
✅ Reduced Installation Errors
Field installation teams rely on P&ID symbols to identify valve type and orientation. Clear symbol understanding prevents installation of wrong valve types or incorrect actuator configurations.
✅ Compliance with Tender Specifications
Tender documents reference P&ID symbols to define valve requirements. Understanding these symbols ensures your procurement matches the exact technical specifications outlined in the project tender.
About KELOR — Butterfly Valve Supplier from Ahmedabad, India
KELOR (Krishna Industries) sources industrial butterfly valves from verified manufacturers whose products comply with ISO 10628, ISA S5.1, and ASME Y32.2 symbol standards — every supplier vetted for quality, dimensional accuracy, and testing compliance. We provide the required technical details, specification sheets, and documentation that EPC contractors, consultants, and plant procurement teams need.
- Verified source model: Every butterfly valve sourced from vetted and quality-certified manufacturers
- Wide range: Wafer type, lug type, double flanged butterfly valves in Cast Iron, Ductile Iron, SS304, and SS316
- Actuation options: Manual (hand lever), pneumatic, electric (motorized), and hydraulic actuation
- Documentation: Mill Test Report 3.1 can be provided on request
- GST registered, Pan India dispatch, since 2017 — India’s biggest supplier of industrial butterfly valves
Need Butterfly Valve Symbols Documentation for Your Project?
KELOR provides technical details, specification sheets, and symbol reference documentation for all butterfly valve types sourced from verified manufacturers. Contact us for project-specific requirements.
Frequently Asked Questions (FAQ)
What does a butterfly valve symbol represent?
A butterfly valve symbol represents a quarter-turn valve that uses a rotating disc to regulate flow through a pipeline. In P&ID diagrams, it is depicted as two triangular shapes (bowtie shape) positioned along the pipeline, indicating the valve body and disc orientation. The symbol conveys the valve type, its location in the piping system, and its identification tag number for reference in engineering documents.
Are butterfly valve symbols standardized?
Yes, butterfly valve symbols are standardized under international standards including ISO 10628 (Process flow diagrams — general rules), ISA S5.1 (Instrumentation symbols and identification), and ASME Y32.2 (Graphic symbols for pipe fittings, valves, and piping). DIN standards also provide additional symbol guidelines used in European engineering projects. These standards ensure universal understanding across international project teams.
Is there a different symbol for wafer and lug type butterfly valves?
Yes, while the basic butterfly valve symbol remains the same (bowtie shape), the body type is indicated through additional markings or annotations on the P&ID. Wafer type butterfly valves are shown without flange markings on the symbol, lug type butterfly valves include threaded lug indicators on both sides, and double flanged butterfly valves show flange markings on both ends of the symbol. These distinctions are critical for accurate Bill of Materials preparation and procurement.
How do I identify an actuated butterfly valve symbol?
Actuated butterfly valve symbols are identified by the actuator symbol attached to the basic butterfly valve symbol. Pneumatic actuated valves show a diaphragm or cylinder symbol on top of the bowtie, electric actuated valves display a motor symbol (letter “M” inside a rectangular box), and hydraulic actuated valves show a hydraulic cylinder symbol. Gear operated valves include a gear symbol (interlocking circles) on top. Each actuator type also includes fail-safe position annotations (FO, FC, or FL).
Where are butterfly valve symbols used?
Butterfly valve symbols are used across multiple engineering and project documents including P&ID (Piping and Instrumentation Diagrams), PFD (Process Flow Diagrams), piping isometric drawings, plant layout drawings, and engineering Bill of Materials (BOQ) sheets. They are essential reference points for EPC contractors, piping designers, instrumentation engineers, procurement teams, and field installation crews.
Can butterfly valves be used for throttling?
Yes, butterfly valves can be used for throttling and modulating control applications. When shown on a P&ID, a modulating butterfly valve symbol indicates that the valve can partially open or close to regulate flow, pressure, or temperature. High-performance butterfly valves with offset disc designs (high-performance butterfly valves or double offset butterfly valves) are particularly suited for throttling service in water treatment, HVAC, chemical processing, and power generation applications.
What industries use butterfly valves the most?
Butterfly valves are most commonly used in water and wastewater treatment, oil and gas pipelines and processing, power generation (cooling water and circulating water systems), chemical and petrochemical processing, HVAC and fire protection systems, and food and beverage processing. Their compact design, quarter-turn operation, and cost-effectiveness make them ideal for large-diameter piping applications across these industries.
Does KELOR supply valves as per international symbols?
KELOR sources butterfly valves from verified manufacturers whose products comply with international symbol and engineering standards (ISO 10628, ISA S5.1, ASME Y32.2). We provide the required technical details, specification sheets, and documentation that EPC contractors, consultants, and plant procurement teams need for their projects. Every supplier is vetted for quality, dimensional accuracy, and testing compliance before being added to our supply network.
Why are symbols important in B2B projects?
Valve symbols are critical in B2B projects because they serve as the universal language between design engineers, EPC contractors, procurement teams, and installation crews. Standardized symbols ensure correct valve selection, accurate Bill of Materials (BOQ) preparation, proper installation, and compliance with tender specifications. They reduce miscommunication, prevent costly errors, and ensure that the right valve is procured and installed at the right location — especially in large-scale international projects.
Can I source butterfly valves in bulk from KELOR?
Yes, KELOR specializes in bulk B2B supply of industrial butterfly valves and exports across India and internationally. Being India’s biggest supplier of butterfly valves, we offer wafer type, lug type, and double flanged butterfly valves in Cast Iron, Ductile Iron, SS304, and SS316 — with manual, pneumatic, electric, and hydraulic actuation options. Contact us via WhatsApp or email for competitive bulk pricing and project-specific quotations.
KELOR Krishna Industries — Industrial Butterfly Valve Supplier India
India’s biggest 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.