The Challenge
The FPSO Bunga Kertas had localised hull corrosion below the waterline at multiple locations, requiring an in-situ subsea repair approach rather than dry docking. The repair methodology relied on welding habitats secured and sealed against the hull, with water evacuated to create an atmospheric workspace for welded hull repairs.
The Solution
Cube Offshore developed the structural design for three subsea hull welding habitat types. We used finite element analysis to assess stiffened steel plate structures under 2 bar external hydrostatic pressure and applied AISC 360-16 and DNVGL-ST-E273 acceptance criteria. The design adopted 6 mm habitat plate with 100 mm x 12 mm stiffeners, with geometry tailored to different hull curvatures. We also assessed a modified Type A habitat with a bolt-on adaptor. Our detailed fabrication drawings supported manufacture of the three habitat configurations.
The Scope
- Structural concept development
- Finite element stress analysis and code compliance
- Assessment of three habitat geometries and the Type A adaptor modification
- Engineering design report
- Detailed fabrication drawings for the three welding habitat types
CAD model of habitat.
FEA model of Habitat
Fabrication drawing of habitat
