A high performance, 30 MIL high density polyethylene membrane encloses the primary tank and provides secondary spill containment.
The second stage of manufacturing consists of wrapping the steel tank with a minimum of 1/4” thick Styrofoam (foam) insulation and an impervious barrier of 30-Mil high-density polyethylene membrane (HDPE). The 30-Mil HDPE provides containment for the remote possibility of a fuel leak through the steel tank. A leak detector pipe terminating in the secondary containment provides a positive-proof that the tank is not leaking.
Another advantage of the 30-Mil HDPE is that it shields and protects the steel tank exterior from coming in direct contact with concrete and thus minimizes the potential risk of tank external corrosion.
Certain Authorities Having Jurisdiction require metallic secondary containment. Convault® manufactures double wall steel tanks to meet the above requirements. The secondary steel containment is wrapped in 30-Mil poly to prevent external corrosion. In effect this tank system provides triple containment; namely, primary steel tank, the secondary steel tank and tertiary 30 Mil poly.
Convault also provides Non-Metallic Secondary Containment and Venting by Form of Construction.
The ConVault AST is listed in accordance with ULC 142.16, ULC 142.23 and UL Standard 2085 Insulated/Secondary Containment for Aboveground Storage Tanks/Protected Type. The UL 2085 Standard listing officially recognizes Convault® tank of having a secondary containment. Technically, this is equivalent to a protected and insulated double wall steel tank. Therefore, the Convault® tank provides you a secondary containment equivalent to a double wall steel tank plus protection of six-inch reinforced concrete.