Cathodically protected steel tank

sti-P3® double‐wall underground storage tank features a pre‐engineered corrosion protection system that provides ongoing monitoring of corrosion protection. The sti‐P3® system has provided reliable, long‐term performance for over a quarter million steel underground storage tanks.

sti-P3® Features

  • Meets UL 58, UL 1746‐Part 1 and ULC‐S603.1
  • The only UST design which allows on‐going monitoring of corrosion protection, providing peace of mind
  • Can be used with a variety of leak detection systems
  • Steel provides complete compatibility with all blends of ethanol and biodiesel fuels
  • Impermeable to all petroleum products and vapors
  • First national UST corrosion control standard with over 40 years of successful performance
  • Flat end design reduces the cost of installation and increases site layout flexibility
  • Steel inner tank provides structural strength, while its exterior wall is continuously protected with three methods of corrosion control
  • Various backfill options allow for money‐saving installation
  • Capacities range up to 60,000 gallons
  • Single or double‐wall steel construction

sti-P3® Benefits

  • Steel construction allows for recycling
  • Low cost compartments and customization
  • Built to nationally‐recognized STI standards with strict third‐party quality control inspection program

Sti-P3® is available from an extensive group of Steel Tank Institute fabricators who participate in the STI Quality Control Program. Under the program, independent quality control inspectors make unannounced visits to STI members, ensuring fabrication to the highest possible standards.


  • sti-P3
  • Tank Technologies
  • Underground