LNG Tank Sloshing Assessment Methodology - The New Generation

This paper presents ExxonMobil’s evolution of a direct sloshing assessment methodology to resolve several challenging technical issues that are essential for evaluating integrity of LNG containment systems. Among the most significant developments is the introduction of a probabilistic-based framework that facilitates modeling of the high variability of sloshing impact pressures due to sloshing physics and insulation materials that is inherent in products from natural sources (e.g. plywood, etc.). This probabilistic-based framework also provides the basis for a reliability-based assessment of structural integrity. In addition, this methodology furthered the technical basis of Scaling Law that supports the use of sloshing test as the method for prediction of design sloshing loads, addressed tank sloshing and ship motion coupling effects in deriving inputs to drive the sloshing test rig, demonstrated the influence of membrane surface structures on sloshing pressures, and developed limit state structural capacities as a function of loaded area. The authors are hopeful that this methodology enhances the foundation for achieving continuous safe operation of LNG carriers and enables sound design of offshore LNG loading and receiving terminals.