U-Won Double-Wall Tank


U-Won Double-Wall Tanks consist of a steel tank complying with UL 58 standard with a non-metallic external FRP jacket (Non UL standard tank pictured).

Steel tank made of 6 mm to 8mm of SS400/A36 structure steel is conducted with leakage test and inspection for entire welded parts. Once tests are passed, 0.1 mm thick anti-corrosion poly ester resin is applied. PE mesh and PE film are applied on the coated tank, and then a minimum 3 mm thick FRP layer is fabricated with glass fibre and poly ester resin. PE mesh and PE film layer makes a 1mm interstitial space between tank and FRP layer.

All U-Won Double-Wall Tanks imported to Australia are quality checked by JCC Suntech then an ethanol protective resin coat is applied on the interior of the tank.

We can supply tanks from 10KL up to 50KL in size with compartments available from 20KL.

U-Won Double–Wall Tank & Wall cross-section

a. Leak detection system

Leak detection system consists of monitoring interstitial layer, leak detection sensor and control box.

Monitoring interstitial layer formed between steel tank and FRP layer acts as a secondary containment barrier, preventing water ingress into the tank and product leakage out into the earth. If ingress or egress has occurred the leak detection sensor sends the information to the control box inside the service station store.

The leak detection system is fitted while pipe works are being installed.

Leakage detection system plan
Leakage detection control box & sensor

b. Overfill prevention system

Overfill prevention system operates closing valve inside fill pipe when product level in tank reaches a certain level. The operation mechanism is simple and effective, and an automatic closing device is installed inside the fill pipe.

Overfill prevention device position
Leakage detection control box & sensor

c. U-Won Double-Wall Tank manufacturing overview

U-Won is equipped with automatic machineries such as NC cutting, bending and automatic submerged arc welding machine. They result in high quality and accuracy of products.

In addition, U-Won Double-Wall tanks go through several stringent inspection stages. Firstly, after single-wall steel tank is manufactured, entire welded sections are inspected by an outsourced non-destructive inspection company. Then the tank thickness is inspected using ultrasound and magnetic once more by KFI (Korea Fire Institute).

Final inspection is conducted on completed double-wall tanks, FRP layer thickness test and air pressure test for both interior tank and monitoring interstitial layer. All inspections are managed by U-Won.

Finally, before their release, KFI inspects tanks that passed internal tests by applying pressure test at 70 kPa of interior tank and 20 kPa of monitoring interstitial layer.

After completing final test, monitoring interstitial layer is vacuumed at -1 bar to detect cracks in the FRP which can occur during delivery.

d. U-Won Double-Wall Tank manufacturing process

i. Stocked steel material thickness test

ii. End plate cutting and bending

iii. Body plate bending and automatic welding

iv. Assembly welding

v. Manhole guide and lift lug welding

vi. Steel tank inspection

vii. Anti-corrosion coat

viii. Containment layer fabrication

ix. FRP laminating

x. Double-wall tank inspection