Abstract
In strong collaboration with the oil company consortium, contractor and their subcontractors successfully designed and installed a novel Water Intake Riser (WIR) on Prelude FLNG, the world's largest FLNG facility. The scope involved transforming a concept into reality by close collaboration between the contractor and client team at various offices and worksites from project start to offshore installation. Preparation for this operation included activities at various locations around the world such as Factory Acceptance Testing in Norway, USA, UK and France. The final Site Integration Testing was performed at the FLNG in South Korea before Prelude FLNG left the yard.
Designing a Water Intake Riser (WIR) at this scale capable of surviving 10,000 years cyclone with a design life of 25 years has raised a variety of engineering challenges including; riser head-loss, loadings under survival events, novel flying leads and umbilicals, fatigue of key element such as chains, spacer-frames and riser girth welds. Full-scale tests were performed on critical components of the WIR for example the rubber hose, chain, and connectors. In addition, the system was tested at scale in model scale basins.
Offshore execution in Australia involved the installation of large diameter steel pipe sections assembled with merlin connectors and the largest submersible pumps of their kind inside the FLNG Hull. Bespoke installation aids were used such as an over-the-side Riser Assembly Tower. Successful execution required maintaining Prelude FLNG at a favorable heading to minimize motions and achieve millimeter precision pipe assembly.
