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.