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Liquefied Gas Containment Systems

The most important property of a liquefied gas, in relation to pumping and storage, is its saturated vapor pressure that exerted when the liquid is in equilibrium with its own vapor at a given temperature. An alternative way of describing a liquefied gas is to give the temperature at which the saturated vapor pressure is equal to atmospheric pressure, in other words, the liquid's atmospheric boiling point.

LNG is carried at about -160 degrees Celsius in specially engineered cryogenic containment systems. There is much variation in the design, construction and operation of gas carriers due to the variety of cargoes carried and the number of cargo containment systems utilized.

Cargo containment systems may be of the independent tanks (pressurized, semi-pressurized or fully refrigerated) or of the membrane type.

  • Membrane tanks are non-self-supporting tanks which consist of a membrane supported through insulation by the adjacent hull structure.
  • Independent tanks do not form a part of the ship's hull. An independent tank is not essential to the hull strength. There are three types of independent tanks; type A and B are gravity tanks, primarily constructed of plane surfaces and type C, also referred to as pressure vessels, are spherical or cylindrical tanks meeting pressure vessel criteria.

Essenmotion provides comprehensive design-build services for liquefied gas containment systems designed for different pressure and refrigeration regimes, cargoes with different boiling point and vapor pressure properties, primary and secondary barriers, operational requirements, failure scenarios and containment configurations.