Double Wall Tanks

Double wall tanks are being used in more and more applications everyday to provide secondary containment for petroleum storage. We find they are being used by contractors, resellers, fleet fueling sites, municipalities, marine installations, small businesses and on an increasing level, even agricultural operations – YES FARMS. See “SPCC Information Fact Sheet for Farmers” to determine if your farm must meet the EPA requirements.

Double wall tanks meet the secondary containment requirements of the SPCC specifications as well as those of most regulating authorities. Visit EPS.GOV SPCC Regulations for the latest on SPCC requirements and guidance documents.

Southern Tank manufactures a complete line of cylindrical (horizontal and vertical) and rectangular double wall tanks ranging in capacity from 550 gallons to 25,000 gallons, as shown by the images on this page as well as some of our gallery images. Rectangular tanks can be made to your size requirements within the boundaries of UL fabrication procedures. Double wall tanks are made of carbon or stainless steel and are available in a wide range of exterior coatings and colors. Interior linings can be applied for your specific product needs and compatibility. Double wall tanks are built and labeled to UL and/or Steel Tank Institute (STI) standards. A variety of UL approved supports is available for our horizontal and rectangular double wall tanks (see Tank Accessories). I beam supports are available to keep the vertical double wall tanks up off the ground to allow for visual inspection.

The overwhelming majority of double wall tanks are the Type I variety. Type I double wall tanks are tight-wrapped meaning there is intimate contact of the inner and outer tanks. Southern Tank manufactures these tanks daily to the UL 142 standard as well as the Steel Tank Institute F921 standard. We first build a UL 142 inner tank and then wrap it with a UL 142 outer tank for secondary containment. Every tank that we build is leak tested per UL requirements as is the interstice – the area between the two tanks. This interstice is tested by applying a vacuum of 18″ Hg and holding it a minimum of 2 hours. The 2-hour fire-tested Flameshield® is also a Type I double wall tank. The fire-protected Fireguard® is a Type II UL 2085 double wall tank with a thermal lightweight insulation material in the interstice.

A Type II double wall tank has a measurable and consistent space between the inner and outer tanks, but it doesn’t necessarily require the insulating material. Type I and Type II double wall tanks comply with most all local, state and federal code requirements for secondary containment. Southern Tank can also supply all required equipment to trim your tanks and complete your code requirements. Items such as fill systems with overfill and spill protection, emergency and working vents, gauges, alarms, pumps, leak detection devices and so on can be provided.