Storage Tank Flame Arrester Testing and Inspection: Standards, Samples, Methods and Requirements

Storage tank flame arrester testing and inspection verifies that vent-mounted flame arresting devices can reliably stop flame propagation, withstand stabilized burning, and maintain adequate breathing capacity throughout their service life. Evaluations are carried out in accordance with recognized standards such as EN ISO 16852, ASTM F1273, UL 525 and GB/T 13347, combining type testing at accredited third-party laboratories with periodic in-service inspection. This article explains the working principles, sample types, testing items, test methods, applications and frequently asked questions related to storage tank flame arrester qualification and inspection.

Technical Overview

A storage tank flame arrester is a passive safety device installed at the vent opening of an atmospheric storage tank containing flammable liquids such as crude oil, gasoline, solvents or alcohol. Its function is to allow vapor and air to pass freely through the tank vent while extinguishing any flame that could otherwise travel back into the tank vapor space due to lightning, static discharge, external fire or ignition at the vent outlet.

Operating Principle

Flame arresters quench flames using an element constructed from narrow, repetitive passages, typically formed by crimped metal ribbon, parallel plates, perforated sheet or wire gauze. As a flame front enters these passages, heat is rapidly extracted to the passage walls and free radical chain reactions are interrupted, so combustion cannot be sustained beyond the element. The maximum passage gap must be smaller than the maximum experimental safe gap (MESG) of the gas or vapor mixture to be arrested, a classification concept consistent with the IEC 60079 series for gas groups IIA, IIB and IIC.

Device Categories

Depending on installation and hazard, flame arresters are classified into end-of-line deflagration arresters mounted on atmospheric vents, in-line deflagration arresters installed in pipework close to the ignition source, detonation arresters designed to stop stable or unstable detonations in long pipe runs, and hydraulic (liquid seal) arresters. Many tank installations combine the arrester with a breather valve or pressure and vacuum relief valve in a single assembly.

Standards and Regulatory Framework

Principal references include EN ISO 16852 (performance requirements, test methods and limits for use for flame arresters), ASTM F1273 and UL 525 for flame arresters on tank vents, API 2210 for application guidance on petroleum storage tanks, and Chinese national standards such as GB/T 13347 for flame arrester performance and test methods, together with tank farm design codes such as GB 50074. Type approval testing is normally performed by accredited third-party laboratories, while in-service inspection is carried out by plant inspection personnel or accredited third-party inspectors.

Why Testing Is Necessary

Even a correctly selected arrester can degrade in service. Corrosion, fouling by wax, polymers, dust, ice or insect nests, mechanical deformation of the crimped element, and gasket deterioration can enlarge flame paths or restrict breathing capacity. Regular testing and inspection therefore verify both safety performance and ventilation function, protecting the tank from internal explosion and from overpressure or vacuum damage.

Testing Samples

End-of-Line Deflagration Flame Arresters

Complete vent-mounted units representative of production design, including housing, element, weather hood and bird screen, submitted for type testing against deflagration flame transmission and endurance burning requirements.

In-Line Deflagration Flame Arresters

Units intended for installation in connected vapor piping, tested together with representative pipe sections and, where applicable, pre-volume configurations defined by the relevant standard.

Detonation Flame Arresters

Heavy-duty units qualified for stable detonation and unstable detonation service, tested with long straight pipe runs sized to the nominal diameter of the device.

Replacement Elements and Cores

Crimped ribbon, parallel plate or wire gauze elements supplied as spare parts, verified for gap dimensions, material grade and interchangeability with the certified housing.

Breather Valve and Flame Arrester Assemblies

Integrated pressure and vacuum relief assemblies containing an arrester element, where both the relief function and the flame arresting function are evaluated together.

For type approval, new production samples are submitted in the quantities and mounting orientations specified by the applicable standard. For periodic inspection, samples typically consist of the actual in-service device removed from the tank vent together with maintenance records and prior inspection reports.

Testing Items

Typical testing and inspection items for storage tank flame arresters include:

• Deflagration flame transmission resistance testing at low and high flame speeds
• Stable detonation and unstable detonation transmission testing for in-line arresters
• Endurance burning test with a stabilized flame held on the element
• Short-time burning test for restricted operating conditions
• Pressure drop and flow capacity testing across the operating range
• Housing strength and burst pressure verification
• Corrosion resistance testing, including neutral salt spray exposure
• Material verification, including chemical composition and minimum thickness of housing and element
• Dimensional verification of element gap width, length, layer count and free flow area
• Gasket, seal and weather protection integrity checks
• Marking, nameplate and instruction conformity with the applicable standard
• In-service visual inspection for fouling, corrosion, deformation and blockage

Testing Methods

Flame Transmission Testing

The arrester is mounted on a test pipe of the same nominal diameter using the intended mounting orientation. A flammable gas mixture representative of the designated gas group, such as stoichiometric propane for group IIA, ethylene for group IIB or hydrogen for group IIC, is ignited at defined positions in the pipe while flame sensors record whether flame passes through the element. The device passes only if flame transmission does not occur and no structural failure is observed over the required number of ignition attempts, covering both low-velocity and high-velocity deflagration conditions.

Detonation Testing

For detonation arresters, the test pipe is extended so that the flame accelerates to a stable detonation before reaching the arrester, or the ignition position and conditions are adjusted to produce unstable detonation with the highest pressure and flame speed envelopes. The arrester must arrest the detonation without flame transmission and without rupture, permanent distortion or loosening of the element.

Endurance Burning and Short-Time Burning Tests

A flame is stabilized directly on the arrester element to simulate continuous ignition at the vent, such as flame from a lightning strike or a sustained external fire. Thermocouples monitor element temperature while the stabilized flame is maintained for durations that depend on the endurance burning class assigned under EN ISO 16852. The device passes if the flame self-extinguishes or burns out without flame transmission or element burn-through. Shorter-duration short-time burning tests apply to arresters with restricted operating limits.

Flow Resistance and Pressure Drop Testing

Air or the specified gas is passed through the arrester at increasing flow rates while the pressure differential across the device is measured. The resulting flow capacity curve is compared with the manufacturer rating and with the tank breathing demand calculated from filling, emptying and thermal inbreathing and outbreathing rates, confirming that the arrester does not cause unacceptable tank pressure or vacuum.

Corrosion and Environmental Testing

Samples are subjected to neutral salt spray exposure in accordance with methods such as ISO 9227 or ASTM B117 for the specified duration, then examined for corrosion products, material loss and function. Where required by the standard, flame transmission performance is retested after environmental conditioning to confirm that corrosion has not degraded arresting capability.

Material and Dimensional Verification

Chemical composition of housing and element materials is verified by spectrometric analysis against the declared grade, for example austenitic stainless steel or aluminum alloy. Wall thickness, element gap dimensions, passage geometry and free area are measured with calibrated instruments and compared with the certified drawings and the MESG-based limits for the designated gas group.

In-Service Inspection Procedure

Periodic inspection typically involves isolating and removing the arrester, visually examining the element under adequate lighting, gently cleaning the element with an approved solvent and soft brush without disturbing the crimped passages, checking for corrosion, deformation, blockage and gasket condition, verifying gap condition against the manufacturer criteria, reassembling with correct torque and confirming free breathing before returning the tank to service. Inspection results, cleaning dates and any element replacements should be documented in the tank integrity file.

Applications

Storage tank flame arrester testing and inspection supports safety and regulatory compliance across a wide range of facilities handling flammable liquids and gases:

• Refineries and petroleum tank farms storing crude oil, gasoline, jet fuel and diesel
• Chemical plants storing solvents, aromatics, ketones and other flammable liquids
• Ethanol, biodiesel and renewable fuel production and distribution terminals
• Rail and road loading terminals with vapor collection piping
• Oil and gas production sites, including produced water and condensate tanks
• Wastewater treatment plants with digester gas and biogas handling systems
• Paint, coating, adhesive and pharmaceutical intermediate storage facilities
• Marine terminals and bulk liquid storage depots subject to fire code and insurance audits

FAQ

How often should a storage tank flame arrester be inspected?

Most manufacturers and fire safety codes recommend inspection every six to twelve months, with more frequent checks in fouling, freezing or corrosive service. The interval should be adjusted based on service history, product volatility and risk assessment, and shortened if fouling or corrosion is observed.

What is the difference between a deflagration and a detonation flame arrester?

A deflagration arrester stops subsonic flames near the vent or in short pipe runs, while a detonation arrester is built to stop supersonic stable or unstable detonations in long or complex piping. Detonation arresters have stronger housings and longer elements and must be type tested under detonation conditions.

Can a flame arrester element be cleaned and reused?

Yes, provided the element is not corroded, deformed, melted or plugged with deposits that cannot be removed by gentle solvent cleaning. Elements with damaged crimped passages, enlarged gaps or thinning material must be replaced with certified spares of the same design.

Which standards govern flame arrester qualification?

EN ISO 16852 is the most comprehensive international standard covering performance requirements and test methods, complemented by ASTM F1273 and UL 525 for tank vent applications, API 2210 for application guidance, and GB/T 13347 together with GB 50074 in Chinese tank farm practice.

Is type testing by an accredited third-party laboratory mandatory?

For a flame arrester to be marked and sold as compliant with EN ISO 16852, UL 525 or equivalent standards, type testing by accredited third-party laboratories is required, and the manufacturer must maintain production control so that delivered units match the certified design.

What are the most common causes of flame arrester failure?

Typical causes include corrosion of the element or housing, plugging by wax, polymer, dust, ice or insects, mechanical damage during maintenance, missing or degraded gaskets, and fouling that restricts breathing and imposes vacuum or pressure on the tank. A documented inspection and cleaning program addresses nearly all of these failure modes.