• Permatank
• Composite Tank
• Double Wall steel

The World's Premium Underground Storage Tank

The Permatank® is the premium underground storage tank manufactured by Forgeweld and is the product of choice of many major petroleum-marketing companies worldwide.

This revolutionary tank design, colloquially referred to as the "jacketed tank", was developed in the mid 1980's by the Permatank Corporation of the USA. Permatank® has always led the industry in innovation. Long before governments became concerned with the underground storage of hazardous materials, Permatank® had already addressed the issue with double-wall tanks and secondary containment technology. Double-wall tanks are easily monitored by mechanical means and are not subject to rupture, cracking or the types of failure typical of other secondary containment systems.

Permatank® patented technology is only available to licensed members of the Steel Tank Institute of America of America (STI), the holders of the patent. Forgeweld has been manufacturing the Permatank® since 1992. Today we are one of the world's major producers of Permatanks® and our market is growing all the time.

Secondary Containment for Complete Peace of Mind

The Permatank® is a UL 1746-labelled double-wall steel tank consisting of a strong SANS 1535/UL 58 steel primary tank enclosed within a 360° Fibreglass Reinforced Polyester Resin (FRP) secondary containment tank. The steel inner tank ensures structural strength and product compatibility while the FRP outer tank provides corrosion resistance and dependable secondary containment. Shipped with a factory installed Precision Test System to assure double-wall integrity and equipped with an interstitial leak detection monitoring system, it is designed for peace of mind of installer, petroleum marketer and the public at large.

Greater Structural Strength

The primary and secondary tanks are separated by a polyethylene mesh and polyester film barrier. An aboveground vacuum gauge or an electronic monitoring system continually monitors this interstice for the slightest malfunction.

Permatanks® are completely compatible with all blends of conventional and oxygenated fuels, including methanol.

Unsurpassed Environmental Security

The full-thickness inner steel tank provides the high strength needed to prevent buckling and cracking, even under the most severe geotechnical stress. Unlike some other secondary containment underground storage systems, there have been no reports of Permatanks® splitting or cracking after being placed underground and pressed into service. Simply said, Permatanks® have an outstanding safety record - undeniably the best in underground storage.

Image right: Cross-section through a Permatank® UST showing the inner steel tank and outer FRP secondary containment tank, with the stand-off mesh and mylar sheathing visible between the two.

The secondary containment tank is constructed of FRP applied over a stand-off mesh and mylar sheathing. This specially patented process provides an interstice between the inner and outer walls, allowing the migration of fluids and the detection of any leak before a release can occur. The construction process of the FRP outer tank results in an unique ten layer laminate 2.7mm thick. This laminate cures to form a strong, continuous, hermetically sealable outer tank which completely isolates the primary tank from the underground environment. This coating is checked for discontinuities by a 35 000 volt holiday test over the entire surface. Once the coat has been cured, a vacuum of 100kpa is drawn on the interstice to prove tightness and a vaccum gauge installed to verify tightness. On installation, this gauge can be removed and more sophisticated monitoring equipment installed.

Permatanks® are fitted with a monitoring tube running from the top to the bottom of each tank and terminating in the interstitial zone. This feature allows for the monitoring of leaks through 98% of the tank surface. No form of cathodic protection is necessary. Tanks are fitted with dished or flanged ends. Each tank is fitted with lifting lugs and is marked with a plate containing data relating to the manufacturer. Sizes are made to order.

Exceeding the World's Toughest Standards

Our Permatanks® conform to and exceed some of the toughest standards in the world:

• UL 58 - Underwriters Laboratory Standard for Steel Underground Tanks for Flammable and Combustible Liquids: this United States Standard covers the design and fabrication of the structural steel tank.

• UL 1746 Part III (Jacketed Tank): Underwriters Laboratory Standard for External Protection System for Steel Underground Tanks: this code makes it mandatory to provide monitoring of the interstice for leaks.

• European Union CEN Standards

• At present, no South African Bureau of Standards certifications exist which cover Jacketed Tanks. Our Permatanks® exceed SANS 1535: Glass-reinforced Polyester-coated Steel Tanks for the Underground Storage of Hydrocarbons and Oxygenated Solvents and Intended for Burial Horizontally. The presence of a measurable vacuum means that there is no need to site leak tests after installation as called for in Clause 15.2 of SANS 10089-3: The Petroleum Industry Part III: The Installation of Underground Storage Tanks, Pumps/Dispensers and Pipework at Service Stations and Consumer Installations.

Image right: A Forgeweld Permatank® UST being installed in Singapore

We are so confident of our Permatanks® that we offer a thirty-year limited warranty covering failure caused by external corrosion.

Permatank®

The Industry's Best Value in Underground Storage Tanks

And the Intelligent Business Decision

We encourage all our customers to read the applicable codes - the protection of property, people and environment is everyone's responsibility. Copies are available from Standards South Africa or see www.stansa.co.za.