Inpex’s Ichthys project in the Browse Basin has two massive floating structures, the Central Processing Facility (CPF) and the FPSO. The mooring system for these requires a total of 49 off, 5.4m diameter driven pile anchors. The piles were designed and fabricated under sub-contract, by the CPF and FPSO suppliers, Hyundai and Daewoo respectively. The piles were transported and installed by the URF contractor (McDermott and Heerema). The driven pile design required input from these three primary suppliers. Cube was engaged to facilitate completion of the design by coordinating the interface between the many subcontractors located in several international cities.
The pile designs included large thickness cast padeyes for shackles with 275 mm diameter pins. The primary challenge of the coordination and interface was the incorporation of the installation requirements into the design. These requirements included the complex follower and free fall deceleration and arrestor system and fatigue considerations during driving. A design risk assessment was used to overcome the lack of precedence and applicable codes.
Detailed design and installation of the piles went smoothly. Each pile weighed about 600 tonnes.