The Korean Register (KR) has developed new class rules that completely revise the existing structural rules for membrane-type LNG carriers.
The new class rules apply the concept of equivalent design wave (EDW) based on direct load analysis to determine structural arrangements and scantling that meet the structural strength, buckling, and fatigue strength criteria for various load scenarios, and re-verify it by applying direct structural analysis.
The newly developed rules cover not only the general sizes of LNG carrier, but also the ultra-large LNG carriers – the 210,000- to 266,000-cubic-metre ships – by analysing and reflecting the motion characteristics of these vessels. The new rules have also been developed to fully comply with the International Gas Carrier (IGC) Code.
In order to test and improve the rules, KR conducted an impact analysis on an LNG carrier working in collaboration with Hyundai Heavy Industries, Daewoo Shipbuilding and Marine Engineering, and Samsung Heavy Industries and applying LNG carrier building technology.
As a result of verifying the rules for the latest design of 170,000-cubic-metre class membrane-type LNG ship, each shipyard also evaluated the rules as highly competitive rules in terms of structural safety and optimised design.
It is anticipated that the structural design time for LNG carriers will be drastically shortened through the inclusion of the new rules in KR’s structural scantling and strength evaluation program SeaTrust-HullScan, which is already widely used by many design companies and shipyards.
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