SF Double-Wall
Underground Tank
Maximum environmental protection with Steel (Inner) + Fiberglass (Outer) dual-layer engineering. Designed for high water table sites with a 30-year anti-corrosion warranty and continuous leak monitoring.
Superior SF Tank Engineering
The SF (Steel-Fiberglass) tank is a dual-wall underground storage solution that eliminates the risk of environmental contamination. By combining the structural strength of carbon steel with the external corrosion immunity of FRP, we provide the safest fuel storage system for modern gas stations.
Dual-Wall Security
Featuring a secondary containment shell, the S/F tank provides a 3.5mm+ interstitial space. This "tank-within-a-tank" design ensures that even if the primary wall fails, the fuel remains safely contained.
Corrosion-Proof Shell
The outer jacket is made of high-strength Fiberglass Reinforced Plastic (FRP). Unlike traditional steel tanks, it requires no cathodic protection and is immune to aggressive soil and groundwater.
24/7 Leak Detection
The interstitial gap can be equipped with vacuum, pressure, or liquid sensors. This allows for continuous monitoring and automated alerts, meeting the strictest EPA environmental mandates.
Engineered for 30+ Years
Our SF tanks undergo rigorous spark testing (outer shell) and air-pressure testing (inner tank) to ensure structural integrity in the most challenging underground environments.
Technical Specifications
| Parameter | Standard Specification | Technical Details |
|---|---|---|
| Standard Compliance | UL 58, UL 1746, PEI/RP100 | Fully compliant with EPA UST regulations. |
| Primary Tank (Inner) | Q235B / Q345R Carbon Steel | High-strength steel shell, thickness 6mm - 12mm. |
| Secondary Jacket (Outer) | Fiberglass Reinforced Plastic (FRP) | Anti-corrosion resin coating, thickness ≥ 4mm. |
| Interstitial Gap | Minimum 3.5mm Clearance | Uniform space for dry/liquid leak monitoring. |
| Capacity Range | 10m³ to 100m³ (Customizable) | Available in Single or Multi-compartment. |
| Leak Detection Port | Standard 4" NPT Monitoring Well | Ready for vacuum, pressure, or liquid sensors. |
| Lifting & Handling | Integrated Heavy-Duty Lugs | Calculated for safe empty-tank hoisting. |
| Outer Shell Testing | High-Voltage Spark Test | 100% pinhole-free outer jacket verification. |
Active Interstitial Monitoring
The S/F double-wall structure creates a critical 3.5mm+ interstitial space. This cavity acts as a fail-safe zone, allowing for continuous, 24/7 leak detection.
📡 Vacuum & Pressure Monitoring
By maintaining a constant vacuum or positive pressure within the interstitial space, any change in the gauge reading immediately signals a breach in either the inner steel wall or the outer FRP jacket.
💧 Hydrostatic Liquid Monitoring
The interstitial space is filled with a monitoring fluid (brine). High or low-level liquid sensors detect volume changes caused by fuel entering the space or brine leaking out, ensuring absolute containment verification.
Factory Testing & Compliance
Every SF tank is subjected to a rigorous multi-stage quality control process to ensure 100% leak-proof performance and compliance with global safety mandates.
High-Voltage Spark Test
The entire FRP outer jacket is scanned with high-voltage electricity to detect micro-pinholes or structural inconsistencies, ensuring the secondary shell is 100% impermeable.
Dual-Stage Pressure Testing
Independent air pressure tests are performed on the inner steel tank (Primary) and the interstitial space (Secondary) to verify weld integrity and seal durability.
Ultrasonic Flaw Detection (UT)
Critical weld seams on the carbon steel inner tank undergo ultrasonic testing to identify any internal defects, ensuring structural safety under underground pressure.
FRP Adhesion & Thickness Check
We verify the bonding strength between the steel and fiberglass layers and perform ultrasonic thickness measurements to ensure the FRP jacket exceeds the 4mm standard.
Installation & Site Application
SF double-wall tanks are engineered for rapid deployment and lifelong environmental safety, especially in challenging geological conditions.
Direct Burial Technology
Unlike traditional steel tanks, the SF tank's FRP outer jacket allows for direct burial without the need for additional concrete vaults, significantly reducing civil engineering costs.
- No Cathodic Protection Required: FRP is naturally immune to soil electrolysis and rust.
- Pea Gravel Backfill: Ensures uniform pressure distribution and structural stability.
- Anti-Floatation Design: Optimized anchoring systems for high water table regions.
- Rapid Setup: Reduces site construction downtime by up to 50% vs single-wall tanks.
Retail Gas Stations
The standard choice for modern fuel retail networks. Complies with strict urban environmental regulations and simplifies 24/7 leak monitoring compliance.
Coastal & High-Water Sites
Designed for aggressive environments. The FRP jacket provides a permanent barrier against saltwater intrusion and acidic soil corrosion.
Emergency Power Backup
Reliable underground diesel storage for data centers, hospitals, and critical infrastructure requiring long-term fuel integrity and zero spill risk.
Essential FAQs
What is the expected service life of an SF tank?
Are these tanks compliant with EPA UST regulations?
Can the tank be compartmentalized for different fuels?
How does the leak monitoring system work?
Project Support
Regulatory Compliance
Full UL 1746 and EPA documentation for site environmental permits.
Foundation & CAD
Provision of standardized DWG drawings for concrete slab and excavation specs.
Monitoring Integration
Pre-fitting for vacuum monitoring or probe-based leak detection systems.
Custom Compartments
Internal baffling engineered for multi-fuel site configurations.
Ready to Build a Safer Fuel Station?
Consult with our engineering team for custom drawings and a detailed project estimate within 24 hours.
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