STI-F921 Double Wall Steel Tanks

Southern Tank fabricates STI F921® above ground tanks with a focus on durability, environmental safety, and compliance. Designed with a double-wall steel structure, these tanks provide built-in secondary containment that is both testable and impermeable. Whether used for fuel storage, chemical containment, or facility backup generator systems, the F921® tank is a reliable solution for a wide range of applications.

Standard Features of the F921® Tank

Double-wall steel construction for primary and secondary containment
Horizontal, vertical, and rectangular configurations available
Testable interstitial space for continuous leak detection
Compatible with a broad range of fuels and chemicals
Available in sizes up to 30,000 gallons*
UL 142 listed for both the primary and secondary tank walls
Meets EPA SPCC regulations and STI F921® specifications
UL-approved saddles and skids available for installation of horizontal tanks, vertical tanks can be flat or sloped bottom, on legs or a skirt support.
Can be relocated easily depending on application

Certified Manufacturing and Quality Assurance

Every F921® tank is fabricated by an STI licensed manufacturer and constructed to meet strict third-party inspection standards under the Steel Tank Institute’s Quality Assurance Program. These inspections help ensure that every tank meets exacting standards for safety, quality, and performance.

Leak Detection and Monitoring

The double-wall design includes an interstice between the inner and outer walls that can be monitored, allowing for early detection of leaks. The interstitial space is designed to be testable in the field and complies with EPA and UL guidelines for secondary containment and leak monitoring.

Options and Customization

Custom compartments for cost-effective multi-product storage
Variety of UL 142 listed support designs for all configurations
300° (standard) or 360° outer wall coverage for containment integrity
Interior coatings for product compatibility
Specialized exterior coatings for superior corrosion protection
Stainless steel inner tank with carbon steel outer or all stainless steel or carbon steel

Applications

STI F921® tanks are widely used in industries that require aboveground secondary containment systems:

Fleet fueling operations
Backup generator fuel storage
Bulk chemical and oil storage
Data Center fuel and fluid storage
Farms storing large volumes of fuel

Need Help Specifying the Right Tank?

Our experienced team can help guide your decisions to meet your project requirements. Contact Southern Tank to learn how to enhance your storage safety system with an F921® double wall tank.

*STI allows capacities exceeding Southern Tank’s capabilities. Typically in a horizontal configuration we are limited to 12’ dia. and 27000 gallons. Vertical is 30000 gallons and rectangular will be determined by dimensions.