Each of the 16t certified modules will be lifted from a supply vessel onto the FPSO using a gantry system incorporating high-speed winches. Then, it would be skidded into position.
The lift line will be lowered after the supply vessel is secured alongside the FPSO. It will then be connected to the sling attached to the accommodation module. The line will be tensioned to begin the lift. Lifting the initial few meters will be at high speed to overcome any motion from the supply vessel. Tag lines will assist with controlling the load during the lift. The first accommodation module will be lifted to the correct height by the winches. Then, it will be moved horizontally towards the deck by luffing the gantry. Once the container has reached the appropriate position, it will be rotated by 90° so it can be maneuvered between the bumper frame and gantry legs and onto the deck.
Sliding pads will be installed underneath the container to connect to a skidding system. Afterward, the second accommodation module will be lifted similarly and lowered on top of the first where it can be secured. Both modules will then be skidded into position. The accommodation modules will be jacked up to remove the sliding pads and secure them in their final place. This procedure will be repeated for the third and fourth modules, with the gantry structure and its interface connections removed to enable the final positioning.
It was a well-designed plan, enabling operations in greater detail and within safety requirements. Conbit’s gantry lifting solution should provide the opportunity for more efficient installations of certified modules on FPSOs. This alternative lifting solution avoids the need for extensive and expensive crane vessels, offering significant cost savings to FPSO projects.
This gantry lifting solution is also a proven methodology used for many other projects, such as flare tip replacements on FPSOs and other offshore oil rigs.