Hamburg: DNV is currently launching a new LNG sloshing Class Note for membrane tank systems. One of its main purposes is to provide guidelines for assessing sloshing in the new large size LNG carriers in order to ensure safe transportation.

Liquid motion resonance in LNG cargo tanks can lead to sloshing impacts at sharp corners and knuckles inside the tank, with a potential risk of damage.

DNV’s new class note has been developed in response to the new challenges facing the LNG industry; increased size of LNG carriers, offshore loading/unloading and partially filled LNG tanks in connection with part cargoes.

The guideline “Sloshing Analysis of LNG membrane tanks” emphasises sloshing loads and tank system strengths for normal tank fillings as well as reduced tank filling operations of membrane-type LNG carriers.

“One of the main purposes behind DNV’s sloshing research programme and the development of the new LNG sloshing Class Note is to provide guidance for assessing sloshing in increased size larger LNG carriers,” says Sverre Valsgård, who is responsible for DNV’s R&D programme on gas carriers.

Due to uncertainties in the sloshing impact load assessment, a comparative approach is used for assessing the strength of the containment system and the supporting hull structure. The sloshing load and strength of a new LNG carrier design or a carrier operating with partly filled tanks are compared to the sloshing load and strength of the existing fleet of membrane-type LNG carriers that have a record of trading without sloshing damage.

For more information or to make an appointment for an interview with DNV expertise during the SMM 2007, please call Per Wiggo Richardsen, information manager, +47 90 77 78 29.