This summer the All-Sea team – working alongside 11 other partners – completed in-situ, offshore insert repairs on a FPSO (Floating Production Storage and Offloading vessel) 350km off the coast of Newfoundland. With less than a one month weather window per year, such an undertaking is understandably difficult to do in that location. The project itself was green-lit just two months before the required execution, and the full scope was unknown due to a flooded compartment on the vessel.
The first phase of the repair was cofferdam design, fabrication and validation. The cofferdam was designed to DNV standards and required a complete design verification report (DVR). This phase involved structural calculations, modeled static finite element analysis, laser scan surveys to ensure an exact fit, full NDE and load testing.
Once complete, Phase 2 of the repair began – focusing on cofferdam rigging and installation. A complete offshore mechanical handling plan was done. Utilizing an ROV for visual aid, and an internal drop camera for seal verification, this phase was completed without the use of divers to success.
Phase 3 was the hull repair itself – a permanent vessel hull insert repair to Class Approval. Dual habitat systems were used for spark mitigation. Pre and post-NDE, 100% visual, UT and MPI inspections were completed. At the beginning of the project, the expected insert size was 200mm x 400mm, with corrosion damage estimated to be contained within the weld seam. The actual insert was much larger than originally thought, at 1360mm x 1182mm, in addition to a caisson piece that was 762mm in height.
Ultimately, this project was completed successfully and safely without incident, and had many notable achievements. It involved the first Sub Sea lift from this FPSO. It became the first “Diverless” cofferdam installation, the first welding operation during full production, and the fastest DNV VerCom. It is truly a testament of the professionalism and experience of the All-Sea team to accomplish such a feat in a location that not only presented many challenges, but a project with so many unknowns and moving parts. It’s also a great display of teamwork on the part of all collaborators involved in getting the job done together, safely, and with the highest quality.