Liquefied Natural Gas (LNG) is natural gas including Methane  and some mixture of Ethane that has been cooled down to liquid form for ease and safety of non-pressurized storage or transport. It takes up about 1/600th the volume of natural gas (at standard conditions for temperature and pressure). It is odorless,colorless,non toxic and non corrosive. Hazards include flammability after vaporization into a gaseous state, freezing and asphyxia 

The liquefaction process involves removal of certain components, such as dust,acid gases,helium, water, and heavy hydrocarbons, which could cause difficulty downstream. The natural gas is then condensed into a liquid at close to atmospheric pressure by cooling it to approximately −162 °C (−260 °F); maximum transport pressure is set at around 25 kPa (4 psi).

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A typical LNG process. The gas is first extracted and transported to a processing plant where it is purified by removing any condensates such as water, oil, mud, as well as other gases such as CO2 and H2S. An LNG process train will also typically be designed to remove trace amounts of mercury from the gas stream to prevent mercury amalgamating with aluminum in the cryogenic heat exchangers. The gas is then cooled down in stages until it is liquefied. LNG is finally stored in storage tanks and can be loaded and shipped.