Saturday morning saw another small Canadian town disrupted
by the derailment of a fuel train with subsequent fire and explosions. This
time it was Gainford, Alberta near Edmonton that saw the effects of the fire
and explosions. The train was transporting crude oil and liquefied petroleum
gas (LPG). Thirteen cars derailed and apparently only three LPG cars (of the
nine that were derailed) were actually involved in the fires and explosions.
The four crude oil cars are not apparently leaking or burning. No deaths or
injuries are being reported at this time.
The Incident
As is typical with a flammable gas fire, the local fire
departments are not trying to put out the fire. Instead they are just trying to
contain the fire to the area of the derailment. If the fire were extinguished
while gas in the car was still leaking it would result in an explosive vapor
cloud that could further damage nearby cars and cause further leaks.
A photo from the RCMP (see cropped version below) show a typical
flame jet from a pressurized gas release from a small hole or broken line. The
flame appears to be pointed away from other cars, reducing the danger of other
explosions or other cars becoming involved in the fire.
News reports indicate that there were two separate
explosions, but it does not appear from the news photos that any of the three
propane cars actually exploded (not near enough damage). What probably happened
is that leaking LPG formed a vapor cloud that detonated when it expanded to
reach an ignition source. Again, the damage seen in the news photos looks like
the fuel clouds were rather small.
The biggest potential danger in these types of accidents
appears to have been avoided here. When one of the flame jets seen in the RCMP
photo is directed at an intact car carrying either flammable gasses or liquids,
it heats the contents of the car to the point where the pressure builds up in
the car to the point where the flame weakened metal catastrophically fails and
a large gas cloud is released and ignites in a spectacularly destructive
explosion.
It is way too early yet to discuss causes of the derailment.
According to one
news report, a spokesman from the Canadian National Railway Company said
that the tracks had been ultrasonically tested last month and the train had
been inspected Friday.
The Conflict
This accident takes place against a political backdrop where
there are discussions going on in both Canada and the United States about the
large increase in the transportation of crude oil and other fuels by railroad.
These increases are being driving by the resurgence of oil and gas production
in the United States and Canada and the difficulty (physical and political) of
getting pipelines in place to transport the oil and gas being produced either
to refineries or markets.
There are on-going discussions in both countries about
improving rail safety regulations concerning the shipment of fuels. The
proposed regulations under consideration look at both the construction
specifications for the cars transporting the fuels as well as the operation of
trains transporting those cars.
Generally speaking pipeline transportation is safer than
rail which is safer than truck. The flexibility of shipment destinations,
however, is exactly the reverse; trucks are more flexible than trains which are
still more flexible than pipelines. Unfortunately, the pipeline approval and
construction process takes a great deal of time.
BTW: Thanks to a TWEET® from Rob Massey (@irobertcmassey) for pointing me
at this story.
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