Lloyd’s Register (LR) has completed a project to develop a 30,000m3 LNG carrier design with bilobe type »C« tanks together[ds_preview] with Hanjin Heavy Industries & Construction (HHIC).
The small-scale LNG carrier uses the latest technology within the limits of existing shipbuilding methods. According to LR, the vessel concept features significantly improved environmental aspects, a higher level of energy efficiency and improved cargo capacity. Applying bilobe type »C« cargo tank technology makes the vessels very well suited to future LNG trading patterns in coastal waters.
Furthermore LR recently issued GTT an Approval in Principle (AiP) for a membrane cargo containment system (CCS) for bunker ships to allow an increase in vapour pressure of up to 2barg. The AiP follows a joint research and innovation programme between GTT and LR investigating cargo containment behaviour, looking at strength aspects in various applications, sizes and at different pressures. The collaboration between LR and GTT experts, through workshops using experimental and analytical results and data on internal pressures occurring in LNG tanks, studied the maximum compressive strength of the containment system on LNG carriers.
Using a 4,000m3 LNG bunker as a reference case, with two Mark III Flex membrane tanks and structural analysis – while considering navigation and operating conditions – in October 2015 LR issued AiP for a GTT Membrane system with an increase in vapour pressure up to 2barg for use in bunker ships.
Higher vapour pressures in CCS are relevant for gas-fuelled ships and small-scale LNGs – especially for LNG bunkering, to help manage boil-off gas. Strengthening the hull offers additional safety within the tank to withstand the boil-off gas generated.
