Sunday, October 20, 2013

A New Canadian Fuel Train Derailment

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

NOTE: See news reports here, here, here and here.

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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