Double Wall Tanks (UL-142)

FMC Tanks supplies a variety of Double Wall Tanks in capacities ranging from 5 gallons to 30,000 gallons. Single Wall Tanks are available in either Rectangular or Cylindrical Geometries and can be dimensionally modified to accommodate unique requirements. Double Wall Tanks are manufactured by constructing a tank inside of a tank. Cylindrical Double Wall Tanks consist of a primary steel tank wrapped by an exterior steel shell in direct contact with the primary tank. Rectangular Double Wall Tanks consist of a primary steel tank encased within a separate outer steel tank. The primary and secondary tanks are separated by an air-space (from 3”-6” depending on size) created by internal steel stiffening members. The air-space or “interstice” serves as a measurable secondary containment structure in the event the primary tank leaks or is ruptured. Furthermore, the “interstice” created with Double Wall Tank construction serves as a space to monitor and verify the integrity of the primary tank via electronic or visual inspection. All Double Wall Tanks are air-tested at the factory at 5.0 psig to verify tank performance and integrity. Double Wall Tank designs include a “secondary containment” area by virtue of their “tank inside of a tank” design. Many US jurisdictions and regulatory officials now require Double Wall Tanks in an effort to provide vessel redundancy and safety. Please consult your local Fire Code officials and regulatory agencies for guidance with projects requiring Double Wall Tanks.
Double Wall Steel Tanks are manufactured in accordance with Underwriters Laboratories Standard UL142, Aboveground Tanks for Storage of Flammable and Combustible Liquids. This construction standard mandates minimum steel gage thickness meeting ASTM specifications that must be used in the construction of double wall tanks that carry the Underwriters Laboratories UL142 label. All UL142 tanks supplied by FMC Tanks are supplied with the properly sized normal and emergency vent openings to affect the safe venting of tanks in the event of a fire or rapid temperature increase. Customized tank openings and equipment can be ordered and installed at the factory to satisfy specific system requirements. FMC Tanks can supply your tank in carbon steel, stainless steel or aluminum. Interior linings andor exterior coatings can be applied to affect compatibility with unique liquid products or to provide long-term corrosion, chemical and impactabrasion resistance.