Aging Testing of Explosion-Proof Materials for Gas Stations: Standards, Methods, and Performance Eva

Aging testing of explosion-proof materials for gas stations is a critical safety verification process that evaluates how explosion suppression materials—such as aluminum alloy mesh, honeycomb barriers, and polymer-based suppression media—retain their mechanical and deflagration-suppression performance after long-term exposure to fuel, heat, humidity, UV radiation, and corrosive environments. This article explains the sample types, test items, international and national test methods, evaluation criteria, and typical applications of accelerated aging tests for explosion-proof materials used in filling station storage tanks and vapor recovery systems.

Technical Overview

Explosion-proof (explosion suppression) materials are engineered structures installed inside gasoline and diesel storage tanks, fuel transport vessels, and vapor spaces at filling stations. By dividing the flammable vapor space into small cells and rapidly quenching flame propagation through heat absorption, these materials prevent deflagration even when an ignition source is present. Common material forms include aluminum alloy mesh, expanded metal honeycomb structures, polymer-based elastic suppression balls, and composite barrier coatings.

Because these materials operate for years while permanently immersed in fuel or exposed to tank headspace vapors, they are continuously subjected to thermal cycling, hydrocarbon chemical attack, moisture, oxygen, and—during installation or maintenance—ultraviolet radiation and ozone. Degradation such as corrosion, embrittlement, cracking, or loss of mechanical strength can compromise suppression capability and create a serious safety hazard. Aging testing therefore uses accelerated laboratory conditioning to simulate long-term service exposure within a compressed timeframe, after which the material's retained properties are measured and compared against acceptance criteria defined in standards such as AQ 3009, GB/T series methods, ISO, and ASTM test procedures. Accredited third-party laboratories routinely perform these evaluations to support product certification, regulatory compliance, and periodic safety re-qualification.

Testing Samples

Metallic Explosion-Suppression Mesh and Honeycomb Materials

Aluminum alloy mesh, expanded metal sheets, and cellular honeycomb blocks are the most widely used suppression media in underground storage tanks. Aging tests focus on corrosion resistance, structural integrity of welds and joints, tensile and shear strength retention, and dimensional stability after exposure to fuel and humid environments. Test specimens are cut from representative production batches, including both flat material sections and assembled three-dimensional modules, so that joint and connection behavior is captured alongside base material performance.

Polymer-Based Suppression Materials

Elastic suppression balls, polymeric foams, and polymer-coated mesh systems are evaluated for polymer-specific degradation mechanisms: chain scission and oxidation from heat, ozone-induced cracking, swelling or extraction caused by gasoline and diesel immersion, and ultraviolet embrittlement. Standard dumbbell specimens for tensile testing, as well as whole components, are conditioned to measure retention of tensile strength, elongation at break, hardness, compression set, and mass or volume change.

Barrier Coatings and Composite Linings

Explosion-suppression coatings and composite linings applied to tank inner walls are tested as coated panels and free films. Aging evaluation includes adhesion retention after thermal and chemical conditioning, blistering and cracking resistance, and barrier performance verification after accelerated exposure.

Ancillary Sealing and Connection Components

Gaskets, sealing elements, fasteners, and installation hardware used with the suppression system are included in aging programs because premature failure of these smaller components can destabilize the entire assembly. These samples undergo damp heat, salt spray, and fluid immersion conditioning appropriate to their material class.

Testing Items

A comprehensive aging test program for explosion-proof materials typically includes the following conditioning exposures and post-aging property measurements:

• Thermal aging (hot air oven exposure) at elevated temperatures to accelerate oxidative degradation
• Xenon-arc light aging to simulate full-spectrum solar radiation exposure
• Fluorescent ultraviolet (UV) condensation aging for surface photodegradation assessment
• Ozone aging to evaluate static and dynamic ozone cracking resistance of polymeric components
• Damp heat (constant humidity) aging to assess hydrolytic and moisture-driven degradation
• Temperature cycling between extremes to induce thermal fatigue and delamination
• Neutral and acidic salt spray corrosion testing for metallic materials and coatings
• Immersion resistance testing in gasoline, diesel, ethanol-blended fuel, and water
• Post-aging tensile strength and elongation retention measurement
• Hardness change, compression set, and rebound elasticity evaluation
• Mass change and volume change after fluid immersion
• Visual inspection for cracking, blistering, corrosion products, and coating adhesion loss
• Explosion suppression performance verification after aging, using deflagration suppression testing in a simulated tank vessel

Testing Methods

Thermal Aging

Hot air oven exposure is performed following GB/T 3512, ISO 188, or ASTM D573 for elastomeric materials, and GB/T 7141 or ASTM D3045 for plastics. Specimens are conditioned at selected temperatures for defined durations, after which the percentage retention of tensile strength and elongation at break is calculated. Metallic materials may be thermally aged to assess temper stability and joint strength. Test temperatures and durations are chosen to produce a defined aging factor—commonly a required retention of at least 75 to 80 percent of original mechanical properties, depending on the applicable product specification.

Weathering and Light Aging

Artificial weathering is conducted with xenon-arc lamps according to GB/T 16422.2, ISO 4892-2, or ASTM G155, or with fluorescent UV-condensation apparatus according to GB/T 16422.3, ISO 4892-3, or ASTM G154. Exposure cycles combine irradiance, temperature, and moisture to reproduce outdoor degradation. This testing is most relevant for suppression materials stored or installed outdoors before burial, and for aboveground tank applications. After exposure, specimens are examined for surface cracking, chalking, color change, and loss of mechanical strength.

Ozone Aging

Polymeric sealing and elastic components are tested under static or dynamic strain in an ozone-containing chamber following GB/T 7762, ISO 143-1, or ASTM D1149. Specimens are stretched to specified elongation levels and inspected under magnification for the onset and growth of ozone cracks after defined exposure periods. Absence of cracking at the specified strain and duration constitutes a typical pass criterion.

Damp Heat and Temperature Cycling

Constant damp heat exposure is performed per GB/T 2423.3 or IEC 60068-2-78, typically at 40°C or 85°C with relative humidity of 85 to 95 percent, to evaluate moisture absorption and hydrolytic stability. Temperature cycling is conducted following GB/T 2423.22 or IEC 60068-2-14 with rapid transitions between low and high extremes to reveal differential expansion damage, delamination, and fatigue of joints in assembled suppression modules.

Salt Spray Corrosion Testing