So something that has crossed my mind is why do oil train derailment tend to end up in fireballs?
I know the media has some effect on the perception that this happens all the time, I know that not every derailment ends in a fireball .
My question specifically is what is the ignition source of these fires? Crude isn't particularly flammable like gasoline so I don't see a spark from steel on steel impact starting the fire. My gut tells me that it's something more akin to a long term heat source like a diesel glow plug.
Alas the only thing I can think of that may match that criteria would be extremely hot brakes and wheelsets.
What a catch 22! Is it better to have the hot brakes potentially start a fire or let many more cars pile up and potentially leak more oil?
Anybody have actual facts about this? Well reasoned theories?
Modeling the Cleveland and Pittsburgh during the PennCentral era starting on the Cleveland lakefront and ending in Mingo junction
ruderunnerCrude isn't particularly flammable like gasoline...
This is actually one of the problems - apparently it actually is flammable like gasoline. At least the stuff that's going up in fireballs is. That volatility has been discussed here in a couple of threads.
When one thinks of crude, methinks most folks picture something not far removed from sludge, or asphalt. In reality, crude exists in a number of forms, not unlike coal. I'll leave it to others to discuss specifics.
As for ignition sources, don't underestimate the heat that can be generated by metal-on-metal friction, or even the bending of metal. If there are enough volatiles involved (and again, there apparently are in some grades of crude) all it will take is one spark amongst the leaking oil.
Some years back, we went through the same thing with LPG in railroad tank cars. Look up Kingman, Crescent City, and Oneonta.
Not hauling crude notwithstanding, and derailments being a given, even with the best of intentions, the answer is to prevent the leaks, or at least minimize them.
Recall, to, that ethanol burns, and had been involved in several derailment incidents, at least one including a fatality. But ethanol doesn't explode, so it's not going to get the same attention...
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tree68 ruderunner When one thinks of crude, methinks most folks picture something not far removed from sludge, or asphalt. In reality, crude exists in a number of forms, not unlike coal. I'll leave it to others to discuss specifics. As for ignition sources, don't underestimate the heat that can be generated by metal-on-metal friction, or even the bending of metal. If there are enough volatiles involved (and again, there apparently are in some grades of crude) all it will take is one spark amongst the leaking oil. Some years back, we went through the same thing with LPG in railroad tank cars. Look up Kingman, Crescent City, and Oneonta. Not hauling crude notwithstanding, and derailments being a given, even with the best of intentions, the answer is to prevent the leaks, or at least minimize them. Recall, to, that ethanol burns, and had been involved in several derailment incidents, at least one including a fatality. But ethanol doesn't explode, so it's not going to get the same attention...
ruderunner
And this most recent derailment did not have an explosion. Just a fire - the fire is bad enough, don't get me wrong, as it brings more attention to the derailment.
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Crude oil varies from condensate (which is like natural gasoline) to tar. It also has varing amounts of disolved natural gas, propane, etc. The lighter components evolve out of the liquid crude, and the vapors build up in storage tanks, including tank cars. The vapors are especially volatile.
In a typical high speed derailment and pileup, large amounts of flying yellow-white-hot molten metal are produced.
It's been established Bakken crude is particularly volatile. I was mystified myself as to why Bakken crude oil train wrecks were igniting and exploding when as far as I knew plain 'ol crude oil was very difficult to ignite. I even remember reading during the Iran-Iraq War thirty years ago of oil tankers being hit with anti-ship missles and not being heavily damaged, the missile being smothered by the dense crude in the hold. Obviously all crude oils aren't created equal.
Crude oil is graded by weight of voilite compounds in it. Most Middle Eastern crudes are in the 60 range Western Texas is in the 60 range North Sea is in the 70-80 range Tar sand from Canada is in the 80 range. However Bakken is in the 40 range. That stuff is so lightweight that it requires blending with most refiners before it can be refined to useful goods.
Even though all BAKKEN is not equal it appears that generally it has a much higher percentage of volitiles. Start with methane, butane, ethane, propane, hexane, octane, etc. Then there may be as well complex hydorcarbons.
Some of the functions of a refinery are to separate out the various items and combine / separate other petroleum into these products and plastics are an important function.
EuclidIn a typical high speed derailment and pileup, large amounts of flying yellow-white-hot molten metal are produced.
I don't think this is quite right. Has this been substantiated (asI think it was in some instances in the World Trade Center tower collapses, which involved more release of potential energy than any train collision)?
On the other hand, there is no doubt that heavy sparks with enough energy and duration to ignite both vapors and liquid hydrocarbons will frequently be present, as will be heating due to deformation or tearing of car structure, and there is certainly both shock and deformation to spray and perhaps carburete liquid being transported...
Overmod Euclid In a typical high speed derailment and pileup, large amounts of flying yellow-white-hot molten metal are produced. I don't think this is quite right. Has this been substantiated (asI think it was in some instances in the World Trade Center tower collapses, which involved more release of potential energy than any train collision)? On the other hand, there is no doubt that heavy sparks with enough energy and duration to ignite both vapors and liquid hydrocarbons will frequently be present, as will be heating due to deformation or tearing of car structure, and there is certainly both shock and deformation to spray and perhaps carburete liquid being transported...
Euclid In a typical high speed derailment and pileup, large amounts of flying yellow-white-hot molten metal are produced.
White steel is up arounde 2400 degrees F, so I'm somewhat vexed what process could cause this too. You'd be describing something more energetic and faster reacting than the exhaust that burned through the side of a Space Shuttle booster and ate a hole through the bottom of Challenger's external tank...
NittanyLion Typical Bucky BS. Overmod Euclid In a typical high speed derailment and pileup, large amounts of flying yellow-white-hot molten metal are produced. I don't think this is quite right. Has this been substantiated (asI think it was in some instances in the World Trade Center tower collapses, which involved more release of potential energy than any train collision)? On the other hand, there is no doubt that heavy sparks with enough energy and duration to ignite both vapors and liquid hydrocarbons will frequently be present, as will be heating due to deformation or tearing of car structure, and there is certainly both shock and deformation to spray and perhaps carburete liquid being transported... White steel is up arounde 2400 degrees F, so I'm somewhat vexed what process could cause this too. You'd be describing something more energetic and faster reacting than the exhaust that burned through the side of a Space Shuttle booster and ate a hole through the bottom of Challenger's external tank...
Typical Bucky BS.
blue streak 1 Even though all BAKKEN is not equal it appears that generally it has a much higher percentage of volitiles. Start with methane, butane, ethane, propane, hexane, octane, etc. Then there may be as well complex hydorcarbons. Some of the functions of a refinery are to separate out the various items and combine / separate other petroleum into these products and plastics are an important function.
A year or two back, North Dakota passed a law requiring those volatile elements removed before loading into the crude into tank cars. Something that had already been required for pipe lines. Since the new regs took effect, I haven't heard of any derailed oil tanks exploding like previous derailments. Burn yes, but no large explosions.
Jeff
OvermodOn the other hand, there is no doubt that heavy sparks with enough energy and duration to ignite both vapors and liquid hydrocarbons will frequently be present, as will be heating due to deformation or tearing of car structure, and there is certainly both shock and deformation to spray and perhaps carburete liquid being transported...
All it takes is one spark and vapors between the upper and lower explosive levels (UEL & LEL) to start the fire.
For fuel oil #1, the LEL is .7% of the volume of air, the UEL is 5%.
For gasoline, it's 1.4% to 7.6%, ethanol is 3.3% to 19%.
Without knowing the specifics of the crude in question, we can't know the exact LEL and UEL, but I'd bet that at least some of the vapor from any spilled oil was at some point within the required concentration, and thus easily ignitable.
NittanyLion Overmod Euclid In a typical high speed derailment and pileup, large amounts of flying yellow-white-hot molten metal are produced. I don't think this is quite right. Has this been substantiated (asI think it was in some instances in the World Trade Center tower collapses, which involved more release of potential energy than any train collision)? On the other hand, there is no doubt that heavy sparks with enough energy and duration to ignite both vapors and liquid hydrocarbons will frequently be present, as will be heating due to deformation or tearing of car structure, and there is certainly both shock and deformation to spray and perhaps carburete liquid being transported... White steel is up arounde 2400 degrees F, so I'm somewhat vexed what process could cause this too. You'd be describing something more energetic and faster reacting than the exhaust that burned through the side of a Space Shuttle booster and ate a hole through the bottom of Challenger's external tank...
I don't know that there needs to be the energy of the Space Shuttle to melt steel in a train wreck. Sliding wheels or failed bearings seem quite capable of melting steel.
EuclidSliding wheels or failed bearings seem quite capable of melting steel.
Of course they are. But those won't produce large quantities of yellow-hot metal flying through the air.
In my opinion, most of the collision force itself produces bending or breaking, and only incidentally (via friction) produces high heat directly. Of course essentially all the kinetic energy in a moving train that derails winds up as heat relatively quickly -- but I think you are overestimating how much of that energy can be concentrated into high temperature in a large mass of contiguous material through typical processes that occur in accidents.
Overmod Euclid Sliding wheels or failed bearings seem quite capable of melting steel. Of course they are. But those won't produce large quantities of yellow-hot metal flying through the air. In my opinion, most of the collision force itself produces bending or breaking, and only incidentally (via friction) produces high heat directly. Of course essentially all the kinetic energy in a moving train that derails winds up as heat relatively quickly -- but I think you are overestimating how much of that energy can be concentrated into high temperature in a large mass of contiguous material through typical processes that occur in accidents.
Euclid Sliding wheels or failed bearings seem quite capable of melting steel.
What I said is just a generalization. I cannot certify it to be true. Perhaps one of our railroad experts could chime in and provide a certified answer as to what ignites flamable materials in a train wreck.
I have witnessed a derailed loaded hopper picked up at one end by the hook with the cable running about 45 degrees. It was thus lifting and dragging at the same time to draw the hopper toward the hook. Suddenly the hopper surged ahead in travel and dropped in elevation. The hopper bottom hit the rail and skidded on it for about 8-10 feet. It spewed out molten steel leaving spill of yellow molten steel like you might see on the floor in a foundry. It instantly set several ties ablaze, and the section men immediately shoveled dirt on it to put it out. It was pretty amazing because it all seemed like slow motion and it was something that I never expected. I would estimate that it melted 25-50 pounds of steel in about one second as the car slid 8-10 feet.
So I use that tiny example to extrapolate what could happen when 30 cars pile up into a heap at 50 mph.
EuclidPerhaps one of our railroad experts could chime in and provide a certified answer as to what ignites flamable materials in a train wreck.
Would you settle for a firefighter? And I already did.
EuclidI have witnessed a derailed loaded hopper picked up at one end by the hook with the cable running about 45 degrees. It was thus lifting and dragging at the same time to draw the hopper toward the hook. Suddenly the hopper surged ahead in travel and dropped in elevation. The hopper bottom hit the rail and skidded on it for about 8-10 feet. It spewed out molten steel leaving spill of yellow molten steel like you might see on the floor in a foundry. It instantly set several ties ablaze, and the section men immediately shoveled dirt on it to put it out. It was pretty amazing because it all seemed like slow motion and it was something that I never expected. I would estimate that it melted 25-50 pounds of steel in about one second as the car slid 8-10 feet.
ERIKEM ALERT:
I don't have the time and the access to the rubber bible to pull the constants and do the mathematics to debunk this. But it occurs to me that the combination of gravitational potential energy and lateral excursion available in the incident Euclid describes is orders of magnitude less than that required to raise the mass of steel he describes to the temperature he describes, even if the heat transfer could be accomplished 'perfectly' through the contact area between car structure and railhead in 'about one second'. If I am wrong, I'd like to see how wrong in actual numbers.
On the other hand, it would be interesting to see what Euclid did, especially the part about enough evolved metal to set multiple ties promptly on fire. Are there videos of simulated accidents at Pueblo or elsewhere that show contact which melts a significant amount of structural metal?
Euclid Overmod Euclid Sliding wheels or failed bearings seem quite capable of melting steel. Of course they are. But those won't produce large quantities of yellow-hot metal flying through the air. In my opinion, most of the collision force itself produces bending or breaking, and only incidentally (via friction) produces high heat directly. Of course essentially all the kinetic energy in a moving train that derails winds up as heat relatively quickly -- but I think you are overestimating how much of that energy can be concentrated into high temperature in a large mass of contiguous material through typical processes that occur in accidents. What I said is just a generalization. I cannot certify it to be true. Perhaps one of our railroad experts could chime in and provide a certified answer as to what ignites flamable materials in a train wreck. I have witnessed a derailed loaded hopper picked up at one end by the hook with the cable running about 45 degrees. It was thus lifting and dragging at the same time to draw the hopper toward the hook. Suddenly the hopper surged ahead in travel and dropped in elevation. The hopper bottom hit the rail and skidded on it for about 8-10 feet. It spewed out molten steel leaving spill of yellow molten steel like you might see on the floor in a foundry. It instantly set several ties ablaze, and the section men immediately shoveled dirt on it to put it out. It was pretty amazing because it all seemed like slow motion and it was something that I never expected. I would estimate that it melted 25-50 pounds of steel in about one second as the car slid 8-10 feet. So I use that tiny example to extrapolate what could happen when 30 cars pile up into a heap at 50 mph.
Got some proof of that or is it oats that have been processed by the horse?
Norm
The car was filled with crushed rock. The car hopper contacted the rail with its lowest edge at the bottom of its triangular shape, so the area of contact was very small, maybe only a couple square inches or so at the initial contact before sliding. The sudden production of that much molten steel seemed very intrusive and surprising. I was about 50 feet away from it, at a somewhat higher elevation.
Euclid The car was filled with crushed rock. The car hopper contacted the rail with its lowest edge at the bottom of its triangular shape, so the area of contact was very small, maybe only a couple square inches or so at the initial contact before sliding. The sudden production of that much molten steel seemed very intrusive and surprising. I was about 50 feet away from it, at a somewhat higher elevation.
That's not what I asked.
Norm48327 Euclid The car was filled with crushed rock. The car hopper contacted the rail with its lowest edge at the bottom of its triangular shape, so the area of contact was very small, maybe only a couple square inches or so at the initial contact before sliding. The sudden production of that much molten steel seemed very intrusive and surprising. I was about 50 feet away from it, at a somewhat higher elevation. That's not what I asked.
I was not responding to you.
EuclidI was not responding to you.
I think he was responding to me. The issue is not whether or not he saw molten steel -- he probably did. The issue is the "20 to 50 pounds" at the color temperature represented.
My guess is that the actual mass was very much less than that, but well-distributed. It would make sense that the relatively small contact area (between the edge of a sheet reinforced to stay in edge contact and a relatively small railhead area) could produce high temperatures, and that the heat would produce liquidus in the contact area that would be promptly pushed and 'scraped' away thereby maintaining high frictional force in the contact.
But, in the end, the total mass 'melted out' would be that in the 'notch' in the sheet left at the end of the incident, which in 'about one second' would not be very deep, and in any case would not involve more mass than the rectangle described by the rail height and the railhead width (as further wear would bring the bottom of the sheet into contact with the ties and ballast and quickly arrest any remaining motion with minimal melting). I wouldn't figure even that Bekensteinish bound as more than a couple of pounds... and that is an extreme case; pity we don't have a picture of the 'resulting' sheet.
Note by comparison the fireworks involved in a thermite rail weld, and the mass of steel involved in the result. That is not a direct analogy, of course, but it gives you an idea of how dramatic a comparatively small mass can appear to be.
In the Wikipedia entry for nitromethane it mentions that the tank car explosion of 1st June 1958 may have been triggered by adiabatic compression - bubbles of air or other gases can be heated to high temperatures by sudden changes in pressure of the surrounding liquid. The article speculates that the rapid closing of a valve resulted in the pressure change that triggered the explosion.
Oil, unlike nitromethane, does not carry oxygen within each molecule so is not potentially explosive in itself. It is still possible that in certain circumstances bubbles of air, or gases such as propane, could be heated by pressure changes in the oil to provide a source of ignition in the event of a crash.
Sparks of hot steel, sure. That much molten steel, however, sounds pretty unlikely to have been produced by friction over such a short distance. Perhaps the rocks were sulphurous ore?
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What I distinctly recall is that it was not what you would call sparks. It was a flow of liquid discharging from the point of friction sufficient to occupy what must have been several square feet as it landed on the ties and ballast. It resembled the spill of molten steel from the ladle in a foundry if you have ever seen that. It instantly set fire to at least a half dozen ties. That steel structure around the hopper bin openings is quite thick, and I believe there is also added roll formed steel shapes there, riveted to the sheets, and action as a general reinfocement. It is a door and a door frame. I could not see the notch that the rail cut. But I would say that the total melted steel was at least a half gallon in terms of liquid to spread out as much as it did on the ground. I see that is about 32 pounds.
I am not suggesting that every train wreck produces tons of flowing molten metal coursing though the mayhem. If it did, every wreck would start a fire just by ingniting the ties.
I guess to really verify this type of action, one would have to witness several high speed derailments at night when it is dark. I have never seen one.
schlimm Sparks of hot steel, sure. That much molten steel, however, sounds pretty unlikely to have been produced by friction over such a short distance. Perhaps the rocks were sulphurous ore?
Certain types of brake shoes put out an amazing amount of sparks when they're set up against the wheel (esp.if the brakes are in emergency). It can look like a ladel of hot steel being poured.
It's been fun. But it isn't much fun anymore. Signing off for now.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.t fun any
It's easy to estimate the energy of a sliding wheel on a rail. Assume 0.50 coeff of friction, normal force of 286,000/8 to get force per wheel. Force x distance = energy. Plug and chug.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
oltmanndIt's easy to estimate the energy of a sliding wheel on a rail. Assume 0.50 coeff of friction, normal force of 286,000/8 to get force per wheel. Force x distance = energy. Plug and chug.
More plugging and chugging will be needed to answer this question, however, as (at a minimum) both the time rate and the actual contact area will be needed to figure out the actual *temperature rise* involved with the energy release.
In addition, I believe Euclid mentioned there was a momentum component (both down and forward) to the drop in his example, so there is an augmentation of that 'normal' force (which assumes only g as the acceleration)
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