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Client: Australian Operator
Industry: Oil & Gas
Asset: Floating Production Storage and Offloading Unit
Location: North-West Shelf Australia
Year: 2020
Challenge
During the dry-docking campaign, a special class inspection survey identified a repair scope of steel renewal (24 Tons) at 2C Cargo Oil Tank (COT) Swash BHD due to buckling issues. Client requested Nobleseas Engineering to carry out a FEA study to check whether a “stiffener only” solution is feasible.
Scope
Nobleseas Engineering prepared a 3 Cargo-Hold structural model of 2C COT, applied boundary conditions, and incorporated the projected corroded thickness appropriately. The 3CH model used scantling, ballast, global bending moment, and global shear forces as loading conditions. Local structural analysis conducted in accordance with LR ShipRight SDA Primary structure of Tankers 2004 in agreement with loading conditions approved by Llyod Register (LR).
Structural model verified against allowable stresses and critical buckling stresses and proposed stiffening solutions for exceeded allowable criteria along with proposal of modifications to mitigate high stress.
Outcome
It was identified that bulkhead panels have adequate capacity in buckling. The high stresses were shear driven hence stiffener only solution is not feasible. The results from this analysis were used to decide the extent of repair, stiffener only solution or renewal plan for the bulkhead.
