Double Wall Fuel Tanks
A double wall fuel tank is a tank inside a tank: if the inner tank leaks, the outer tank holds the fuel. Most models here are UL-142 tank designs in skid, rectangular, vertical, saddle and bracket styles, and the collection also includes insulated fire-rated double wall tanks. Fleets, contractors, farms and facilities choose them when they want containment built into the tank instead of a separate dike.
How to choose
- Style: skid tanks are the easiest to move with a forklift, vertical tanks save ground space and saddle tanks suit permanent installs. Start with skid fuel tanks if you are unsure.
- Fire rating: if your site needs a protected tank, look at UL-2085 fire-rated tanks, which are insulated as well as double wall.
- Leak checks: plan how you will check the space between the walls, such as with a leak gauge or monitoring port.
- Fittings: confirm the tank's openings match the pump, vents, gauge and fill equipment you plan to use.
Common questions
Does a double wall tank need a containment dike?
The outer tank is the secondary containment, so many sites do not need a separate dike. Local codes vary, so confirm with your fire marshal.
What does UL-142 mean?
UL-142 is the standard listing for steel above-ground tanks for flammable and combustible liquids. Inspectors, fire marshals and insurers often ask for it.
