Will LNG explode? No. LNG is not explosive or flammable in its liquid state. Will LNG burn? No. LNG is a liquid that does not burn because it does not contain oxygen.

Vapor from LNG can burn as discussed below. What happens if LNG spills? If LNG spills it will vaporize. The resulting vapors will warm and expand and become lighter than air. The vapors will disperse with the prevailing wind. What is the risk from a vapor cloud? The risk from a vapor cloud is the potential for a fire. If ignition of a vapor cloud were to occur, the flame will burn slowly back through the vapors to the point of release. Unconfined methane vapor clouds cannot explode.

LNG which is cooled gas to around minus 260 degrees Fahrenheit, making it non-flammable. Leaked LNG would likely vaporize and dissipate, posing little explosion risk, but vapors that are contained in a closed space or gather into a cloud could ignite.

When will a vapor cloud burn? LNG vapors are flammable if they exist at a 5% to 15% concentration in air. If the vapor concentration is lower than 5% it cannot burn because of insufficient fuel. If the vapor concentration is higher than 15% it cannot burn because there is insufficient oxygen. Therefore, the fire hazard of LNG requires 1) a spill or other release from designed containment systems, 2) conversion of the LNG into vapor, 3) the mixing of vapors with air in a 5-15% ratio, and 4) contact of the air/vapor mix with an ignition source.

If LNG vapors were to ignite, flames would burn back along the vapor path toward the source of the spill. How does LNG compare in terms of safety hazards to other substances handled in ports, land based facilities, on roadways and on railways? LNG is not explosive, toxic, carcinogenic or chemically reactive, except for burning which is its value as a fuel source. The vapors are lighter than air. If a spill occurs, the vapor will rise and dissipate leaving no trace in the environment. The flame speed of an unconfined cloud is slow and it will not explode. By contrast, gasoline and fuel oil are extremely flammable and, in their liquid state, are toxic. If these hydrocarbons are spilled the environmental impact is severe.

LNG compared to LPG

LPG stands for Liquefied Petroleum Gas and is 90% propane and butane. LPG is not a natural gas but a mixture of gases originating as a residual product from oil refining. If a leak occurs LNG evaporates in gaseous form, while LPG forms a flammable ‘blanket’ on the ground because it is heavier than air. LNG is a safer fuel than LPG.