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5th May 2017
....continued from Part 1

One took place at a British oil storage depot. The overfilling of a gasoline storage tank in Buncefield, England, in 2004 resulted in massive conflagration that injured 43 people, forced the evacuation of 2,000 and measured 2.2 on the Richter scale.

Another incident occurred at an Amuay oil refinery in Venezuela in 2012 when a pump failed and a cloud of propane rolled across the facility until it found an ignition source.

The explosion incinerated several residential areas, a military post, a hydrogen plant and killed 47 people. Damage exceeded $1 billion.

Atkinson’s review drew some disquieting conclusions. For starters, the worst incidents occurred in nil or very low wind conditions. Small but sustained leaks built large vapour clouds in a matter of minutes that spread through the facilities. In many cases, the flammable zone reached more than 500 metres from the source of ignition.

In other words, a small leak can result in a big bang given the right conditions.

A spill of LNG at minus 165 degrees Celsius can form a vapour cloud. Initially heavier than air because of its low temperature, the cloud, writes Havens, “will spread laterally and remain close to the ground, prolonging both in distance and time the potential hazard to the facility and to the public.”

In a presentation last year to U.S. LNG regulators Atkinson noted that his findings about the threats of vapour cloud explosions applied to LNG export terminals because these facilities all handled refrigerants such as propane and condensates which can form vapour clouds.

Last year, Havens sent a letter to the U.S. Pipeline and Hazardous Materials Safety Administration, which is now reviewing siting regulations.

It ended with one question: “Are the mathematical models which are being used as a basis for approving construction of LNG terminals, with the present focus on export rather than import, being subjected to the necessary scientific scrutiny to ensure that the hazards involved are being correctly identified?”

He hasn’t got an answer yet. [Tyee]