Underground Tanks


	The steel tank that set the performance standard for corrosion protection.

Approximately 1/4 million STI-P3^®steel underground storage tanks (USTs) have been placed in service during the past 29 years using the technology's unparalleled 3-way combination of pre -engineered corrosion prevention features. Since 1969, the STI-P3^®system has established a verified record of dependable performance.

During recent years, society's wishes for the protection of the environment and underground water reserves have resulted in Alaska's requiring secondary containment of USTs. A double wall UST is basically a tank within a tank that meets these mandates. Many tank specifiers prefer double wall without regard to regulatory requirements, and secondary tank usage has continued to increase.

Steel has proven to the the most flexible and durable material to withstand the powerful forces exerted upon USTs in Alaska. Our tanks are built to the STI-P3^® standard using long established steel fabrication technologies coupled with state-of-the-art coatings, cathodic protection, and electrical isolation to provide a durable, reliable UST.


	stands for the three components of STI's cathodic protection technology. STI-P3^® tanks are pre-engineered to provide a cost-effective solution to corrosion protection. The proven strength of steel combined with STI's time-tested protection system. The end result: a storage tank built for a long, dependable service. Here's how it works:


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		Electrical Isolation. Nylon bushings (flange isolators) are employed at each tank opening to isolate the tank from contact with the other steel surfaces: pipes, hold-down straps, etc. Stray currents are thus prevented from entering the tank and anode power is focused exclusively on the coated tank surface.

Dielectric coating. A measurable thickness of specially formulated coating covers the entire surface of the tank. Applied to the sandblasted steel surface, this tough barrier completely coats the tank and isolates the steel from the back fill to prevent corrosion.

	Galvanic anode. Designed for varying soil conditions, the sacrificial anode has a higher energy level than steel and thereby provides protective current to any steel surface inadvertently exposed to soil. This action also protects the tank in case coating damage occurs during installation.