Types of LNG Carriers and Potential Hazards
LNG (Liquefied Natural Gas) carriers are tankers used to transport liquefied natural gas. These LNG carriers use a variety of cutting-edge, adaptable technology, including tanks constructed of unique materials that maintain the cargo at a very low temperature.
Almost all the time, steam turbines are driven by boil-off gas from LNG, boiled liquid fuels like oil, or a mix of the two that powers the propulsion systems of LNG carriers.
These LNG carriers release fewer greenhouse gases than conventional tankers since their propulsion system is powered by natural gas.
Why are LNG Carriers important?
Natural gas was initially transported by overland pipelines, but LNG carriers made it possible to ship enormous volumes via the sea.
Usually, companies transport LNG via shipping it abroad. Transporting LNG via ship is often preferred and in some cases the only, option when LNG plants and fields are located in remote places.
In the 2020s, global LNG demand will continue to rise due to the war commenced between Russia and Ukraine. The increase in global demand has increased the LNG market share and LNG sales.
Types of LNG Carriers
In accordance with the International Maritime Organization’s (IMO) classification of LNG Vessels, LNG tankers are typically categorized depending on their tanks. In general, the IMO classification distinguishes between independent tanks and integral tanks.
Independent Tanks
Independent tanks are tanks that are not a part of the ship hull. In layman’s terms, they are not crucial to the strength of the ship hull.
Moss Tanks(IMO Spherical-Type B)
The working pressure for these tanks is 22 kPa (3.2 psi). However, it can be increased in case of an emergency release. It works at pressures below 700 mbar, but it is mandatory to obtain a partial secondary barrier.
IH Prismatic (IMO Type B)
Ishikawajima-Harima Heavy Industries, which is only used in very few vessels, designed the self-supporting prismatic type B tank. They provide solutions for the membrane LNG tanker spill issue.
These tanks were designed to withstand internal accident damage from internal equipment discharges as a result of numerous previous events.
Small Scale LNG carriers (IMO Type C)
In small-scale LNG tankers, C-type tanks are relatively popular.
Small-scale LNG carrier transport no more than 30,000 m3. These ships transfer LNG in small pieces, or “break-bulk,” from import ports to regions without access to natural gas.
This makes it possible for people living in rural areas and on small islands to get LNG without having to install expensive or unnecessary infrastructure, which reduces regional emissions.
Integrated Tanks
Integrated tanks are tanks that play an important role in the hull strength of the LNG carrier. These tanks are also known as membrane tanks.
TGZ MARK III (AKA GTT Mark III)
These membrane-type LNG carriers are created by Technigas. The tanks contain a 1.2mm waffle design and a stainless steel membrane to absorb thermal contraction while the tank is cooled.
The stainless steel primary barrier, primary insulation, secondary barrier contained within a triplex membrane, secondary insulation, and lastly the hull construction make up this tank type’s layers.
GT96
This type of tank has a primary and a secondary membrane. It is made out of an invariable nickel-iron alloy. Nitrogen hydrocarbon detection serves as a monitoring device for the condition of both membranes.
Potential Hazards of LNG Tanker & Carriers
LNG is actually a chilled, -162 °C, unscented, transparent, and non-toxic form of gas that is normally inflammable but quickly turns into flammable vapors when it makes contact with air.
This characteristic of Liquefied Natural Gas is also one of the main hazard causes. It doesn’t just create fire, it prolongs the burning of the fire due to its nature.
Ship Detonation
Due to the nature of LNG, measures to suppress the chances of detonation and explosion is being seriously regulated in LNG transport.
The engine room, motor room, and cargo compressor room are the three main locations of LNG ships that are most at risk of explosion. Systems for suppressing fires using CO2 extinguishers must be installed in certain regions.
Risk of Spilling LNGs
When the LNG spills over and made contact with water, hazards such as cryogenic burns, suffocation, fires, and explosions might occur. However, LNG spills are not a major issue if no detonation or explosion occurs as LNG vaporizes fairly quickly, leaving no harm to aquatic life
Enhanced Safety
The LNG must be kept in specifically designed shore tanks to ensure its safety while being used onboard. The most typical tank designs for storing LNG include single, double, and full containment tanks.
In case there is a leak, a backup tank is always an option as it is well-kept and maintained.
Conclusion
Different types of LNG carrier caters to different types of needs in terms of LNG shipping. Get in contact with companies such as KLAW LNG to know more about your options and prices.
