Ultimate Guide to Valve Symbols

Introduction: This article provides a comprehensive overview of valve symbols for ball valves, butterfly valves, check valves, globe valves, and gate valves that comply with international standards such as ISO, ANSI, and GB/T.

 

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1. Introduction to Valve Symbols

Valve symbols are standardized graphical representations used in Piping and Instrumentation Diagrams (P&IDs) to depict valve types, functions and operations. They serve as a universal language for engineers in oil & gas, chemical, water treatment and other industries.

Key purposes:

● Clarity in Design: Eliminate ambiguity in technical drawings.

● Global Standardization: Follow ISO/ANSI/ISA standards for consistency.

● Safety & Efficiency: Ensure proper valve selection.

 

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2. Common Valve Symbols with Illustrations

2.1 Ball Valve

● Symbol: Circle with perpendicular line or smaller circle inside

● Function: Quick on/off control with minimal pressure loss

● Applications: Oil, gas, water systems

2.2 Butterfly Valve

● Symbol: Circle bisected by diagonal line

● Function: Compact flow regulation in large-diameter pipes

● States: Normally open (NO) or normally closed (NC)

2.3 Check Valve (Non-Return Valve)

● Symbol: Circle with arrow indicating flow direction

● Function: Prevents backflow in pipelines

● Variants: Swing check, lift check

2.4 Globe Valve

● Symbol: Diamond shape within circle

● Function: Precise throttling in high-pressure systems

● Feature: Good shut-off capability

2.5 Gate Valve

● Symbol: Two triangles pointing toward each other

● Function: Full flow isolation with linear motion

● Advantage: Minimal pressure drop when fully open

 

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3. Valve States & Actuators

 

3.1 Valve States

Symbol Type	Description
	Normally Open (default allows flow)
	Normally Closed (default blocks flow)
Bistable	Retains position during power loss

 

3.2 Actuator Symbols

Actuator	Symbol	Usage
Manual		Handwheel/lever operation
Pneumatic		Compressed air control
Electric		Automated remote operation

 

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Key Standards for Valve Symbols

 

1. ISO Standards

● ISO 5209: Specifies valve marking and symbols for general industrial use .

● ISO 14617: Defines graphical symbols for fluid power systems, including valves .

 

2. ANSI/ASME Standards

● ANSI/ASME Y32.2: Establishes symbols for valves in piping schematics .

● ANSI/ASME B16.34: Covers design and dimensions for flanged, threaded, and welded valves .

 

3. GB/T Standards (China)

GB/T 6567.4-2008: Provides graphical symbols for pipeline systems, including valves .

 

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Conclusion

Valve symbols are essential tools for engineers, technicians, and operators to interpret system designs and ensure safe, efficient operations. By adhering to international standards like ISO and ANSI, these symbols foster global consistency while accommodating industry-specific requirements. Whether designing a pipeline network or troubleshooting a system, understanding valve symbols is critical for accuracy and compliance.