Classification Society, ClassNK issued the “Liquefied Gas Carrier Structures – Membrane System” guidance, to specify the technical requirements when designing membrane-type liquefied gas carriers.
Specifically, the guidelines are composed of the Guidelines for Direct Strength Analysis and specify the requirements for evaluating the yield and buckling strength of the net scantlings of the primary structural members by direct strength calculation.
At the same time,the Guidelines for Fatigue Strength Assessment define the requirements for fatigue strength evaluation for stress-concentrated parts.
The main components include design loads dominant for hull structure, strength analysis methods and corrosion deductions, design scenarios in which assessments are required by the IMO IGC Code, local strength requirements for inner hull structures, and strain control requirements for inner hull structures required by designers of membrane cargo containment systems.
According to ClassNK, calculation function corresponding to the requirements of the guidelines will also be added to “PrimeShip-Hull” series, the Society’s hull structure design support software.
Concluding, the guidelines include evaluation technology for the wave load acting on the hull, and outline the requirements to be considered for the structural strength of membrane-type liquefied gas carriers along with related rules to support rational and efficient designs.