DNV grants approval in principle to new tank design
While LNG tanking and shipping relies on some fairly standard designs, improvements in efficiency and carrying capacity can still have a sizable effect on bottom lines. It is therefore worth noting that early June saw maritime classification society DNV GL grant an approval in principle (AIP) to Kawasaki Heavy Industries’ (KHI) intriguing new MOSS tank design.
Named after the Norwegian firm which first designed them, Moss Maritime, MOSS tanks are one of the industry’s most common designs. Typical vessels using the design may carry four or five tanks. By contrast, non-spherical tanks are used by vessel manufacturers too, but the shape is more common as part of a single continuous tank, rather than the multi-chamber design envisioned here.
KHI says that its design has the same reliability as a conventional spherical (MOSS) tank, but will hold 15% more cargo capacity.
It can also be used with the company’s Panel System, a two-layered proprietary heat insulation system. The low temperature side (tank side) is comprised of phenolic resin foam (PRF) adding anti-cracking properties at low temperatures. The outer, air temperature side is made from polyurethane foam (PUF) covered with an aluminium plastic sheet.
According to DNV, the new tank is an IMO Independent Type B LNG tank that has been developed for use in 180KM3 LNG carriers designed to pass through the new Panama Canal. DNV GL’s AIP involved carrying out comprehensive sloshing and buckling analyses, demonstrating that the new design provided an equivalent level of safety performance to the well-known spherical (MOSS) tank, with no filling restrictions.
The approval is an independent assessment of a concept within an agreed framework, confirming that the design is feasible and no obstacles exist which would prevent its manufacture. Johan Petter Tutturen, business director for Gas Carriers at DNV GL – Maritime, said: “We worked with KHI on the delivery of the first Japanese built LNG carrier – Golar Spirit – in 1981, and that co-operation continues to this day, as she remains in DNV GL class after her successful conversion to a FSRU, a world’s first.”