ClassNK Publishes New Gas Carrier Guidelines

Classification society ClassNK has released its Guidelines for Liquefied Gas Carrier Structures – Independent Prismatic Tanks.

The guidelines, which are available to download for free from ClassNK’s website, specify the technical requirements specifically related to the structural strength assessments of liquefied gas carriers by using direct calculation.

The two components of the guidelines include the Guidelines for Direct Strength Analysis, and the Guidelines for Fatigue Strength Assessment which are currently in development.

The Guidelines for Direct Strength Analysis specify yield strength and buckling strength by direct strength analysis using the net scantling of primary structural members as well as previously released ClassNK guidelines for the structures of other ship types. In addition, the guidelines feature specific requirements for assessment methods taking into account the complex interaction of loads between hull structures and cargo tanks independent from the hull structures. They target independent cargo tank structures and their support structures as well as hull structures.

The guidelines specify not only the design loads dominant for each structure, strength analysis methods and corrosion deductions, but also the design scenarios in which assessments are required by the International Maritime Organization (IMO) International Code of the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk (IGC Code), therefore covering all structural requirements for LGCs with independent prismatic tanks.