GTT inks FSRU deal and sheds more light on new ballast distribution solution

French technological containment specialist Gaztransport & Technigaz (GTT) has been hired by a South Korean shipyard to design tanks for a new floating storage and regasification unit (FSRU). The firm also shared additional details about the new design for liquefied natural gas (LNG) carrier tanks which it presents as a way to boost efficiency and cut costs.

Since the French player has received an order from a Korean shipyard for the tank design of a new FSRU on behalf of an undisclosed Asian shipowner, the firm will design the vessel’s tanks with a total capacity of 204,000 cubic meters (cbm), which will be equipped with the NO96 GW containment system developed in-house. The delivery of the vessels is scheduled for the fourth quarter of 2027.

The containment specialist has also provided more information on its ‘ballast-split’ design for LNG carrier tanks which divides ballast tanks to reduce liquid motion and optimize boil-off rates. As explained, LPG carriers are already operated in a similar way, using the so-called upper wing and double bottom tanks. With the ballast-split design, GTT is proposing a comparable concept for LNG carriers. 

The partitioning tackles issues in partial cargo loading – said to be more challenging than fully loaded or nearly empty cargo situations – to enhance vessel performance. Furthermore, GTT says the new solution improves stability, reduces accelerations, and leads to cost efficiency.

In scenarios of partial loading, both LNG and ballast-water masses are concentrated in the lower regions of the ship, which increases vessel stability but leads to more pronounced accelerations and consequent higher sloshing loads. While the solution currently used for standard LNG carriers entails adhering to established operational filling limits and is suitable for some vessels, other vessels – such as LNG feeders or bunker vessels – require the flexibility to operate at any filling level without restrictions. 

GTT thus proposes a new method – filling the vessel downward, from top to bottom, instead of the traditional bottom-to-top ballasting. This is achieved by dividing the ballast-water tanks into upper and lower sections and initially filling the upper tanks to the required level for achieving the appropriate navigating draft.

While implementing the ballast-split solution requires a higher number of ballast tanks, resulting in some additional piping and corresponding valve arrangements, the containment specialist expects vessel cost to remain similar or even lower, due to potential gains for the cargo containment and reduction of steel scantlings. 

With this in mind, the French player designed a new concept of a 30,000 cbm LNG feeder vessel, which demonstrated “significant” benefits, including less sloshing, confirmed through testing in North Atlantic conditions.

The vessel, designed for all LNG filling levels, has two identical cargo tanks equipped with GTT’s Mark III Flex technology.  Last month, the design received approval in principle (AiP) from Japan’s Class NK, which the French player interpreted as a confirmation of its feasibility and potential.

Similar findings dubbed “promising”  have emerged from the application of these principles in the design of a new GTT 12,000 cbm LNG bunker vessel. Furthermore, GTT believes this design can be applied to other liquid gas or various tanker and offshore units.

Alongside developing new solutions, the French player was busy securing contracts employing its existing membrane solution systems last month. The deals included a pair of two-vessel tank design gigs, one with Samsung Heavy Industries and one with Dalian Shipbuilding, and an agreement with Eni to service its floating liquefied natural gas (FLNG) working offshore Mozambique.

Additionally, the firm received a new tank design order from Hudong-Zhonghua for a new LNG bunkering vessel being built for Ondimar Transportes Marítimos. Once constructed, the vessel will be chartered out to TotalEnergies.