What Is a Flame Arrester? Why Is It Necessary?

In storage and transfer systems handling flammable media such as petroleum products, chemicals, solvents, LPG, LNG, and other hazardous gases, one of the most critical safety risks is flashback ignition through piping or vent lines. A single ignition source at the vent outlet or in the surrounding environment can allow flame propagation back into the storage tank, potentially resulting in catastrophic fire or explosion.

To eliminate this risk, international standards such as API 2000, ISO 16852, ATEX, and NFPA 30 strongly recommend or require the installation of a Flame Arrester.

A Flame Arrester is a dedicated safety device designed to allow gas flow while completely preventing flame propagation, thereby protecting storage tanks, pipelines, process equipment, and personnel.

What Is a Flame Arrester?

A Flame Arrester is a safety device installed on vent lines or gas pipelines to prevent flame flashback from external sources or other parts of a system.

Unlike conventional valves that regulate flow or pressure, a Flame Arrester does not control the fluid. Instead, it acts as a physical barrier against flame transmission.

It allows:

• Free passage of gas or vapor
• Pressure equalization within the system design limits

But it blocks:

• Flame propagation
• Fire transmission into the protected system
• Flashback ignition

  

Why Is a Flame Arrester Necessary?

The Risk of Flame Propagation in Industrial Systems

In flammable vapor handling systems, gases are often vented to the atmosphere through vent lines or vapor recovery systems.

If an ignition source appears at the vent outlet—such as:

• Electrical sparks
• Static discharge
• Hot work (welding/cutting)
• External fire exposure
• Operational accidents

the flame can travel backward through the vent line into the storage tank. This phenomenon is known as flashback (flame propagation).

If the tank contains a flammable vapor-air mixture within the explosive range, the consequences may include:

• Tank fire
• Explosion
• Domino effect to adjacent tanks
• Severe personnel injury and asset loss

  

The Flame Arrester as a Critical Safety Barrier

A Flame Arrester provides:

• Prevention of flame entry into storage tanks
• Protection of process piping systems
• Reduction of explosion propagation risk
• Personnel safety enhancement
• Compliance with international safety standards

It is considered one of the essential safety layers in any flammable storage or handling system.

Working Principle of a Flame Arrester

The core technology lies in the Flame Arresting Element, a specially designed metallic structure with extremely fine passages.

Typically made of stainless steel or corrosion-resistant alloys, it contains thousands of small channels.

When a flame passes through:

1. Heat is rapidly absorbed by the metal element.
2. The flame temperature drops below the combustion threshold.
3. The combustion reaction is extinguished inside the element.
4. Only gas passes through, while the flame is stopped completely.

This process occurs instantly and does not require power or external control.

Basic Construction of a Flame Arrester

A typical Flame Arrester consists of:

• Body housing
• Flame arresting element
• Sealing gasket
• End cover for maintenance
• Bolts and fasteners
• Flanged or threaded connections

Among these, the Flame Arresting Element is the most critical component determining performance.

Types of Flame Arresters

End-of-Line Flame Arrester

Installed at:

• Vent outlets
• Tank roof openings
• Direct atmospheric discharge points

Function:

Prevents external flame sources from entering the system.

This is the most commonly used type in petroleum storage facilities.

Inline Flame Arrester

Installed directly on:

• Process pipelines
• Vapor recovery systems
• VOC recovery lines
• Gas distribution networks

Function:

Prevents flame propagation within pipeline sections.

Deflagration Flame Arrester

Designed to stop deflagration (subsonic flame propagation).

Common applications:

• Vent lines
• Gas pipelines
• Vapor recovery systems

Detonation Flame Arrester

A high-performance type designed to withstand:

• Extremely high pressure waves
• Supersonic flame propagation (detonation)

Used in:

• Long pipeline systems
• LPG systems
• LNG facilities
• Hydrogen applications
• High-risk industrial gas systems

Applications of Flame Arresters

Flame Arresters are widely used in:

• Petroleum storage terminals
• Oil refineries
• Chemical processing plants
• Solvent storage facilities
• Methanol storage tanks
• Ethanol storage systems
• Paint and coating industries
• VOC recovery systems
• Biogas plants
• Industrial gas processing
• LPG systems
• LNG systems
• Hydrogen systems
• Aviation fuel storage
• Pharmaceutical and food processing industries

What Equipment Is Flame Arrester Commonly Combined With?

In real-world systems, Flame Arresters are rarely used alone. They are typically integrated with:

• Pressure Vacuum Relief Valves (PVRV)
• Emergency Vent Valves
• Nitrogen Blanketing Systems
• Pressure Relief Valves
• Check Valves
• Vacuum Relief Valves

This forms a layered protection strategy (Layer of Protection concept).

Applicable Standards

When selecting a Flame Arrester, compliance with international standards is essential:

• ISO 16852
• API 2000
• ATEX Directive
• NFPA 30
• KFI Certification
• IECEx (where required)

These standards ensure validated fire protection performance and safe operation.

Selection Guidelines

Proper selection should consider:

• Type of media
• Gas group classification (IIA, IIB3, IIC)
• Operating pressure
• Temperature range
• Installation position
• Flow rate requirements
• Pipe size
• Applicable safety standards
• Actual operating conditions

Selection should never be based solely on price or size.

Maintenance and Inspection

Although Flame Arresters have no moving parts, regular maintenance is still required.

Key maintenance tasks include:

• Cleaning the flame arresting element
• Checking for contamination or blockage
• Inspecting corrosion or damage
• Verifying gasket integrity
• Measuring pressure drop
• Replacing the element when necessary

Typical inspection intervals range from 6 to 12 months, depending on operating conditions.

Conclusion

A Flame Arrester is one of the most critical safety devices in flammable storage and transfer systems.

It plays a vital role in preventing flame propagation, protecting storage tanks, pipelines, process equipment, and personnel from severe fire and explosion hazards.

To ensure maximum effectiveness, the correct selection of type (End-of-Line, Inline, Deflagration, or Detonation), gas group classification (IIA, IIB3, IIC), sizing, and compliance with standards (ISO 16852, API 2000, ATEX) is essential.

For optimal system safety, Flame Arresters should be integrated with Pressure Vacuum Relief Valves (PVRV), Emergency Vent Valves, and Nitrogen Blanketing Systems, forming a multi-layer protection strategy widely adopted in petroleum, chemical, and process industries.