LNG and natural gas (BOG) behaviour

How LNG behaves?

• is a boiling liquid which, because of its low storage temperatures (-163 to -130°C, depending on pressure), is continuously vaporizing into gas (boil-off gas, or BOG) as it absorbs heat from the environment.
• will vaporize and rapidly pressurize a system to bursting point if left trapped between two valves without pressure relief
• will rapidly damage ship-quality steels in the area around a spill; rapid cooling reduces the ductility of steel and its ability to support
load, which can cause brittle fracture of a vessel’s deck or of a steel component of a quayside
• may cause a Rapid Phase Transition (RPT) if it is mixed with water and boils so rapidly that an over-pressure situation occurs; an RPT is
effectively a flameless explosion.

How natural gas (BOG) behaves?

• is heavier than air until it warms to -110°C; so, if it leaks, it will initially flow downwards
• is flammable at concentrations between 5% and 15% in air
• is not odourised and so does not smell like pipeline natural gas
• is not itself visible but causes surrounding water vapour to condense, producing a visible white cloud
• can lead to a lack of visibility within a vapour cloud
• can be cold enough to cause hypothermia, cold burns and frostbite
• may replace oxygen within a vapour cloud preventing people from
breathing (asphyxiation)