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

Abstract

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.