Lloyd’s Register (LR) has awarded Approval in Principle (AiP) to Daewoo Shipbuilding & Marine Engineering Co., Ltd (DSME) for its 98,000 m3 Very Large Ethane Carrier (VLEC) design with new cryogenic material High Manganese Austenitic steel (High MnA) and sloshing-free tank, the first VLEC design to use this type of material, LR said in its release.
DSME’s 98,000 m3 VLEC design is made of DSME-patented ‘Type B’ tank so it can operate with partial loading due to a sloshing-free tank design making vessel operations flexible and efficient, and facilitating multi-port loading/unloading requirements. The newly developed VLEC design also has the potential to carry a variety of different gases such as LNG, commercial ethane/ethylene, pure propane, commercial butane, commercial propane, mixture of propane and butane in any proportion, and propylene.
LR carried out the design appraisal of the midship section, construction profile and the shell expansion drawing of this new VLEC ship design, to ensure compliance against LR’s prescriptive Rules. A structural design assessment, sloshing and scantling assessments were also conducted by LR in accordance with its ShipRight Procedure.
In December 2018, the IMO’s Maritime Safety Committee (MSC) at its 100th session approved the Draft Interim Guidelines regarding the application of High MnA, making this steel more visible and feasible as a competitive cryogenic material. Currently, the application of High MnA steel is only defined for the use of LNG cargo and/or fuel tank, however the material could be expanded as a tank for other cargoes with higher design temperatures than LNG, such as ethane (-90 degree C) and ethylene (-104 degree C) and other specified cargoes as above with same manner as for 9% nickel steel case.