ClassNK updates guidelines on liquefied gas carrier structures

Japanese classification society, ClassNK released its guidelines for liquefied gas carrier structures – independent prismatic tanks, specifying the technical requirements related to the structural strength assessments 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, ClassNK said in a statement.

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 IMO IGC Code, therefore covering all structural requirements for LGCs with independent prismatic tanks, the statement reads.