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LNG carrier is a ship designed for transporting liquefied natural gas (LNG). As the LNG market is growing rapidly also the fleet of LNG carriers is in a tremendous growth at the moment.

LNG Carriers under construction at DSME shipyard, Okpo

Diagram of newbuilding rate.

The first ship Methane Princess was taken into operation in 1964 and remained in operation until 1998 when it was scrapped. Until the end of 2005 a total of 203 vessels has been built and only 10 of them have yet been scrapped.

At the moment there is a boom in the fleet as there is a total of more than 140 vessels on order at the worlds ship yards. Today the majority of the new buildings are in the size of 120,000 m3 to 140,000 m3. But there are orders for ships with capacity up to 260,000 m³.

Today there are four containment systems in use for new buildings. Two of the designs are of the self supporting type, while the other two are of the membrane type and today the patents are owned by Gaz Transport & Technigaz's (GT&T).

There is a trend towards the use of the two different membrane types instead of the self supporting storage systems. This is most likely due to the fact that the investment required by the shipyards lower.

When transporting natural gas the gas is cooled down to approximately -163 degree Celsius where it will condense to a liquid kept at atmospheric pressure. The tanks onboard the LNG carriers will in fact function as a big thermos where the liquid will be boiling during the voyage. If the gas was not let out of the tank the pressure would slowly build up.

This design is owned by the Norwegian company Moss Maritime and it is a spherical aluminum tank.

Ishikawajima-Harima Heavy Industries has developed a self supporting tank type. This tank type is very similar to the ones used on the first ship, Methane Princess. The tank is made of aluminum

This design is originally by Technigaz and it is of the membrane type. The membrane consists of stainless steel with 'waffles' to absorb the thermal contraction when the tank is cooled down.

This is Gaz Transport's tank design. The tanks consists of a primary and secondary thin membrane made of the material Invar which has almost no thermal contraction. The insulation is made out of plywood boxes filled with perlite.

• LNG carriers on order or under construction