What Is the Function of Air Release Valves in Petrochemical Pipelines?


Introduction

At GA Valves, we provide air release valves specifically engineered for petrochemical environments, with a focus on systems where the fluid passing through the valve is sea water—commonly used in offshore and onshore fire-fighting systems. These valves are designed to perform in harsh, corrosive conditions and maintain reliability during emergency flow events.
This article answers a foundational industry question:
What is the function of air release valves in petrochemical pipelines—and why are they essential to system performance and safety?

The Primary Function: Eliminating Trapped Air from the Pipeline

The main function of an air release valve is to automatically expel air that accumulates in pipelines during filling, draining, and operation. In petrochemical systems, air can enter through pumps, valves, vacuum points, or dissolved gases coming out of solution under pressure changes.
If left unaddressed, this trapped air can:

• Form air pockets that disrupt flow and reduce system efficiency
• Cause water hammer or pressure surges that damage equipment
• Lead to metering and control inaccuracies
• Accelerate corrosion through increased oxygen exposure
• Create false alarms in pressure sensors or control systems

Air release valves maintain system reliability by venting air at key high points where it naturally collects, ensuring a full, pressurised, and efficient flow path.

Why It’s Critical in Petrochemical Fire-Fighting Systems Using Sea Water

In many petrochemical facilities—particularly offshore platforms and coastal terminals—sea water is the primary fluid used for emergency fire-fighting systems. These pipelines must remain fully primed and ready for immediate operation.
Trapped air in these systems can cause:

• Delayed water delivery during fire emergencies
• Increased corrosion risk due to air-sea water interaction
• Pump cavitation or unstable pressure during rapid activation

Air release valves in these scenarios are vital, ensuring sea water is available without air obstruction when it’s needed most.

Types of Air Release Valves Used in Petrochemical Pipelines

1. Automatic Air Release Valves
Constantly vent small amounts of air during normal operation
Typically installed at high points in the system
2. Kinetic (Large Orifice) Air Valves
Release or admit large volumes of air quickly during pipeline filling or draining
Prevent vacuum conditions on shutdown or emptying
3. Combination Air Valves
Integrate both automatic and kinetic functions
Ideal for complex or critical systems with variable flow conditions
Choosing the right valve type is essential for ensuring air management under all operating scenarios.

Strategic Locations for Installation

To function effectively, air release valves should be installed at:

• High points in the pipeline
• Downstream of pumps
• Points of slope or elevation change
• Pipeline dead ends or closed branches
• Critical control points or sensitive instruments

Each placement ensures the valve can relieve air where it naturally accumulates or where rapid evacuation is needed.

Key Benefits of Using Air Release Valves in Petrochemical Fire Systems

Fast, Unobstructed Flow – Ensures sea water reaches nozzles without air delay

Reduced Surge Risk – Prevents damaging water hammer events

Improved System Readiness – Valves help keep the pipeline “fire-ready” at all times

Corrosion Control – Removes oxygen-rich air that accelerates internal degradation

Operational Confidence – Enhances the integrity and response time of safety-critical infrastructure

Contact us now to see how we can help you!

Contact us by email at sales@gavalves.co.uk or call us on 01484 711983