Did you know? Even amongst the LNG Carrier type of vessel, there are various tank styles with their own unique characteristics!
The tank is a major characteristic of LNG carriers, as it stores the cargo at an ultra-low temperature. There are mainly three types of tanks—Moss type, Membrane type, and Self-supporting Prismatic shape IMO type B (SPB).
The Moss type (independent spherical cargo tanks) is a spherical cargo tank independent from the hull, and each tank uses its own structure to maintain the internal pressure. This type simplifies quality control because it causes relatively less boil-off gas, and construction involves less welding than other styles. Vessels with continuous tank cover over all the spherical tanks were first delivered in 2014, Due to its appearance, this design is nicknamed the sayaendo (peapod) in Japan.
With the Membrane type, cargo is maintained at a lower temperature to absorb the expansion of the gas by using thin inside tanks and covering them with a wrinkled stainless steel “membrane.” It features high visibility toward the front of the vessel because of greater space efficiency in the cargo tanks and minimal protrusions on the deck. Ethane carriers adopt this style.
The Self-supporting Prismatic shape IMO type B (SPB) tank uses aluminum alloy or stainless steel, with heat insulation on the exterior. This type of tank has the advantage of allowing for broader use on deck because it is more easily fitted on the hull in comparison with spherical tanks and has no protruding structures on deck.