Pressure Re-Impulse Diagram of the FLNG Tanks Under Sloshing Loads

Sloshing impact loads can cause severe structural damage to cargo tanks in liquefied natural gas floating production storage offloading units (LNG-FPSOs or FLNGs). Studies of sloshing can be classified into two types, namely, hydrodynamics-related and structural mechanics-related studies. This study is a sequel to the authors’ previous studies (Paik et al. 2015; Lee et al. 2015), but is more related to issues of structural mechanics. In this study, a new method for probabilistic sloshing assessment, which has been previously developed by the authors, is briefly explained. The nonlinear impact structural response characteristics under sloshing impact loads are examined by a nonlinear finite element ANSYS/LS-DYNA method. An iso-damage curve, representing a pressure-impulse diagram, is derived for the self-supporting prismatic-shape IMO B type LNG cargo containment system of a hypothetical FLNG. The insights developed from this work can be useful for the damage-tolerant design of cargo tanks in FLNGs.