MidlandMike Euclid ... The EPA also confirmed that there was no danger of explosion. So where did this dire warning come from? Nobody seems to know. No verification was sought or executed. Once the original consensus was achieved, no further listening, skepticism, or verification was needed or wanted because a decision had been made. EPA said they had no real time information, so how could they have affected the incident commands decision. As part of my hazmet training, regarding unified incident command procedures, as I recall they do a review afterward to see if it was appropriate and if procedures need adjustment in furure incidents.
Euclid ... The EPA also confirmed that there was no danger of explosion. So where did this dire warning come from? Nobody seems to know. No verification was sought or executed. Once the original consensus was achieved, no further listening, skepticism, or verification was needed or wanted because a decision had been made.
EPA said they had no real time information, so how could they have affected the incident commands decision. As part of my hazmet training, regarding unified incident command procedures, as I recall they do a review afterward to see if it was appropriate and if procedures need adjustment in furure incidents.
In this context, 'access to real-time information' largely means that no one at OxyVinyls was being provided with periodically-updated readings of temperature or other information about the state of that car, or the other four.
Perhaps a clear recommendation the NTSB might make, or a NPRM include, is that a manufacturer, owner, or even a clearinghouse like CHEMTREC be provided in "as near realtime as possible" with all the information first responders are capturing and using in their incident response. Note that this can and perhaps should be conducted in parallel without going through 'incident command' or any political or other watchdogging that might delay or censor it.
OvermodNote that this can and perhaps should be conducted in parallel without going through 'incident command'...
Unified incident command means all the players are essentially in the same room. If OxyVinyls was on scene, they should have had a rep in the command post.
If EPA didn't have anything resembling realtime information, and OxyVinyls didn't have any realtime information, who did? Anyone? Bueller?
ICS shouldn't be a bureaucratic impediment. The idea behind unified ICS is that everyone is on the same sheet of music. I'm not sure that was the case here.
At the risk of sounding like I'm slamming someone here - the incident commander may have run square into the Peter Principle. The incident may well have been beyond his level of expertise. Running your run-of-the-mill third alarm structure fire is far removed from what was going on in East Palestine.
Kind of like taking your average branch manager and telling him he is now running the entire corporation.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
tree68 Overmod Note that this can and perhaps should be conducted in parallel without going through 'incident command'... Unified incident command means all the players are essentially in the same room. If OxyVinyls was on scene, they should have had a rep in the command post. If EPA didn't have anything resembling realtime information, and OxyVinyls didn't have any realtime information, who did? Anyone? Bueller? ICS shouldn't be a bureaucratic impediment. The idea behind unified ICS is that everyone is on the same sheet of music. I'm not sure that was the case here. At the risk of sounding like I'm slamming someone here - the incident commander may have run square into the Peter Principle. The incident may well have been beyond his level of expertise. Running your run-of-the-mill third alarm structure fire is far removed from what was going on in East Palestine. Kind of like taking your average branch manager and telling him he is now running the entire corporation.
Overmod Note that this can and perhaps should be conducted in parallel without going through 'incident command'...
HAZMAT incidents from their start are well beyond the training of 99% of the first responders of ALL responding elements - Fire & Rescue, Railroad, State & Local governmental responders.
No one responding 'wants to admit' that what they are facing is beyond their training and abilities - that is until they make a wrong decision and they have to answer for the decision they made - then you get into circular finger pointing.
Never too old to have a happy childhood!
For a possible test of the Vinal Choloride the NTSB, FRA. and others will have to go to the receiver of the Product(s) and take enough samples of exatly same product. Then in independent labatories subject the samples to various tests that will verify actual charasteristics of the VC at various temperatures and pressures. Then compare results with manufacturer published lab results.
If results same good. If not then who knows what/?
Folks, the NTSB hearing is online for anyone to view.
Day 1:
https://m.youtube.com/watch?v=N-nBIg516b0&t=24s&pp=2AEYkAIB
Day 2:
https://m.youtube.com/watch?v=x-QON0Tel1Q&t=4s
The panel discussing the decision to vent & burn, consisting of witnesses from incident command, NS, NS's contractors, OxyVinyl, and a chemical expert* starts about 5:34 (that's 5 hours and 34 minutes) into Day 1.
How about watching it before libeling people and promoting conspiracy theories on the Trains forums. If you don't want to put in the time, then wait until the full NTSB report comes out in a couple years.
Dan
* To be a little bit pedantic, the expert witness is not exactly a "professor" as some have said. He is a retired industry researcher who is an "adjunct professor", which usually means someone who has a Ph. D and teaches a class at a university on a semester-to-semester contract. Doesn't make him any less of an expert, just not necessarily an academic.
A lot of finger pointing and dodging of responsibility. Typical.
charlie hebdoA lot of finger pointing and dodging of responsibility. Typical.
I haven't gotten to the 'expert witness' yet, but an adjunct professor would be at the same level of education as a tenured professor. In short, any 'lacunae' of his understanding of the organic chemistry of monomers could be easily remedied with the professional discipline he will have had. While it is possible that he's describing things based only on his status as a degree'd person, I doubt that anyone interested in "teaching" would voluntarily claim expertise without review.
Wood of NS was interesting in not blaming the hired consultants or the people from Oxy for contributing to the decision. For some reason he seems to have been briefed to keep making statements about NS 'accepting responsibility for the incident' which do not really jibe with his testimony, especially when he starts describing things and almost forgets he's in a formal hearing.
In my opinion, the incident commander has almost hanged himself in his initial testimony. Anyone who uses the passive voice about blame who was the named incident commander at the time... let's just say I see avoidance and an intent to throw other people under the bus.
An interesting repeated detail was that the contractor's testimony involves repeated invocation of the idea that their personnel's safety was paramount. This became particularly evident with respect to hot-tapping the cars as an alternative to breach.
An interesting detail that may take on more importance as the hearing progresses is something Wood noted: in the 'unified command' meeting in which apparently the decision to breach was decided upon, he as NS representative was only present at the beginning, and had to leave for a NTSB meeting before any decisive action was decided upon.
Something had to produce the PRD release that scared experienced wreck consultants (you can see the result in the aforementioned exhibit D-53, and apparently the release was this violent for a protracted time). Note also the discussion, whether an 'excuse' or not, that the PRDs on the cars had been wreathed in flame for the duration of the pool fires, and had shown visible flame around the housing after the pool fires were said to have gone out. Mehtion of cooked O-ring seals allowing vapor bypass has been made at a couple of points so far; it remains to be established how much this influenced the decisions not to approach the cars closely or attempt to remove some of the jacketing and insulation to get a more effective temperature reading.
When looking at the graph of time vs. temperature, note the ordinate on the graph. In 20-degree ambient temperature the scanned temperature of the most 'involved' car spikes twice, then enters a period of 'no data', then is observed to seemingly stabilize for a while before the controlled breach is executed. But note the ordinate on the graph: the car temperature never falls below 127, while polymerization is noted as a risk above the 125 degree level.
OM:
1. You nicely nailed the commander's use of passive voice as a dead giveaway. People use it to either sound objective when they are not or to avoid responsibility.
2. You have more patience than I in listening to that hearing.
Euclid1 A plan and procedure for the immediate evacuation of all people and pets living in the dangerous proximity.
Excerpt from ERG Guide 116(P) [Gases - Flammable (Unstable); polymerization hazard]: IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area for at least 100 meters (330 feet) in all directions. LARGE SPILL: Consider initial downwind evacuation for at least 800 meters (1/2 mile).
Given that every location is different, a specific plan is virtually impossible to create. You draw your circle on a map and set out to deal with it.
Most areas have at least a rudimentary plan, and will execute it given the resources - ie, people. Given a population of about 5,000, I'm willing to bet they have exactly one police officer on duty at a given time. EPFD has 20-30 members - who are going to busy trying to sort out and mitigate the incident.
Some areas now have the ability to do a "reverse 9-1-1" call to people in the affected area wherein landline numbers in the designated area are called with necessary information. Likewise, the appropriate media is generally notified.
For some interesting reading, go to the East Palestine Fire Department's FB page.
EuclidDid anything happen in the derailment and overall cleanup that could have exposed either residents or workers to inhalation or direct contact with vinyl chloride? That’s a yes or no question.
Initially 'fortunately', none of the five cars of monomer was breached, or had piping initially leaking dangerous amounts of the material. The NS contractors noted that the piping on the cars that might have been used or adapted to drain the contents was inaccessible or damaged beyond practical use. They also noted that at least some of the cars were affected by serious nearby 'pool fires' and as a result the cars with functioning PRDs ran a continuous, reigniting low-grade fire within the valve housing, which may have burned adjacent to the seals and spool of the valves for what might have been days. Conversely the low-level burn torched or pyrolyzed any vinyl chloride expelled from the cars, preventing environmental or 'downwind' contamination while the venting was going on with flameholding.
As Tree noted, 'standard procedure' for vinyl chloride is to treat it as a potential explosion hazard until fully established otherwise. OxyVinyls established early that the monomer in the cars was stabilized and that they thought this precluded the chance of progress of polymerization, certainly to the point of rupture or explosion. On the other hand, there were what seemed like clear indications of overheat conditions not related to fire (and presumably any radiation heating of the tank metal by pool fires would have decreased in the 20-degree ambient temperature). The recorded temperature graph reveals not only that the temperature spiked to 138 degrees at the time the decision was apparently reached to schedule the breach-and-burn, but that it decreased and then sharply spiked even higher a little later. At this point you will notice not that the temperature was 'going down' but that there is a fairly extended gap in the data -- how this could possibly occur when it was one of the most critical things to track and record, I have no idea, but perhaps something in the hearing can explain it away. But do not be placated into thinking that because the graph then drops and becomes a horizontal 'continuous-temperature' line, it's evidence against polymerization. Look at the vertical scale: the line stabilizes at about 127 degrees, two degrees higher than the danger point for process polymerization. If the graph had been drawn relative to 0 degrees, this would have been established more clearly.
Is it really necessary for a worker to go crawling around in the mud and chemicals in order to hot tap a tank car?
There is certainly a rich "field for the development of new tools" for this sort of thing. But who would pay for their development, construction, and maintenance, and how would you arrange to get them on the necessary short notice to where they were needed, and stage them with appropriate recovery equipment?
If tank car temperature is an all-important factor, why is there no way to read the entire temperature distribution in a tank car?
The problem discussed in the testimony was that, by the time this sort of work might have been undertaken (just as it would for hot-tapping) the valve excursion pictured in exhibit D-53 went off and scared the hell out of the contracting crew working adjacent to it. Supposedly that valve was blowing at high rate for 60 to 70 minutes, if I understood the discussion properly. This with no pool fire or other obvious source to produce that level of mass flow at valve-activation pressure.
I cannot imagine getting it there next to those tank cars with so many unanswered questions about what was going on.
Expect to see them pilloried for that attitude. I expect to see it claimed that they should have been selfless or 'thought of all the others' and worked as a sort of UXB squad until all the vinyl chloride had been safely extracted. It is difficult to conclude... in hindsight... that they shouldn't have persevered with hot-tapping rather than detonating all five cars simultaneously. But that's easy to see after the fact while sitting in a comfortable chair hundreds of miles away.
It seems to me that two things are needed: 1 A plan and procedure for the immediate evacuation of all people and pets living in the dangerous proximity...
2 A wide range of specialist workers and all of the technical equipment to do the cleanup/containment/recovery job safely as quickly as possible.
Hindsight is always 20/20. Foresight is a different matter.
BaltACDHindsight is always 20/20. Foresight is a different matter.
And rarely is it a "black and white" situation. There are those darned shades of gray.
Euclid Create a system that can deal with the problem with no excuses, even if there are some shades of gray.
All problems would be easy to solve if we could just create a system that solves them!
"Why didn't I think of that?!!"
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
zugmann Euclid Create a system that can deal with the problem with no excuses, even if there are some shades of gray. All problems would be easy to solve if we could just create a system that solves them! "Why didn't I think of that?!!"
Isn't that what AI is supposed to do?
BaltACD zugmann Euclid Create a system that can deal with the problem with no excuses, even if there are some shades of gray. All problems would be easy to solve if we could just create a system that solves them! "Why didn't I think of that?!!" Isn't that what AI is supposed to do?
Train: derails
Trip Op: "manual control needed!"
Greetings from Alberta
-an Articulate Malcontent
Manager: "writes you up for manual control"
EuclidCreate a system that can deal with the problem with no excuses, even if there are some shades of gray.
Have you ever commanded an incident? Of any sort?
Didn't think so. And it shows.
EuclidWhy didn’t that hearing ask about the risk of unburned vinyl chloride falling back down from the cloud? He asked a lot of other questions about the cloud, but not that one.
Perhaps they did not think there was a realistic possibility of that happening.
EuclidSo, I say just get the people and pets out of the range of danger. Cool the tank cars with external spray.
How will you know if the tanks are leaking anyway? What happens when VC mixes with the water mist?
EuclidBut the plus side is that no giant chemical mushroom cloud goes up and spreads uncertainty about its potential health risk. And the cleanup goes forward in a workman like manner with the proper tools. Create a system that can deal with the problem with no excuses, even if there are some shades of gray.
Explosion may still happen. As far as cleaning up in a workman like manner, you me like dealing with all the contaminated water created from spraying, and all the contaminated soil, groundwater and surface water also created as a consequence of that spraying? Who says your solution has no unintended consequences, or gray area?
EuclidLook at the video starting at 7:15:55 where Mr. McCarty speaks. He describes an unburned, white plume jetting upward from a tank car during the burn-off, which he speculates to be polymerization.
The 'unburned white plume' you saw rising in the drone video, which is presumably what Mr. McCarty is describing, is not 'polymerization', which would have slowed or stopped promptly upon the internal pressure being relieved by the breach. Polymerization produces a solid, which does not 'jet' in a 'cloud'. In any case the part of polymerization causing the alarm here is that it is exothermic -- it is the cause of the otherwise-unexplained heat excursions in the car(s).
The result of the breach is a typical boiling-liquid (the monomer being a liquid under pressure even at the heat extremes observed) expanding-vapor (the monomer expanded very rapidly from a great number of nucleation sites in the liquid simultaneously, like overcritical water in a rocket-type boiler explosion or opening a shaken soda can) explosion -- the expansion being further accelerated by the intentional rapid ignition of the expanding plume. It was pretty clear from the drone video that the plume starts out white for what seems more than a second, and only as it begins to rise does it take fire.
That not all the monomer in the plume ignited is clearly recognized from the reports of decontaminating the streams. It seemed evident to me that the blobs of monomer seen on the cold beds under cold water had fallen out of the plume at about that size, and sunk to the bottom on account of their greater density as they quickly reached thermal equilibrium.
In my opinion, had the car been breached after the general manner of the PRD release seen in D-53, so the evolving plume was better shaped and amenable to flameholding ignition, there might have been better experienced 'carburetion' of the monomer in air, and combustion and pyrolysis might have occurred more completely. I think you'd still have the dioxin release question to address, though, among with all the other issues of a kludge response.
Overmod Euclid Look at the video starting at 7:15:55 where Mr. McCarty speaks. He describes an unburned, white plume jetting upward from a tank car during the burn-off, which he speculates to be polymerization. I cannot get this to pull up due to AT&T bandwidth issues, but either you or Mr. McCarty have a major comprehension problem. The 'unburned white plume' you saw rising in the drone video, which is presumably what Mr. McCarty is describing, is not 'polymerization', which would have slowed or stopped promptly upon the internal pressure being relieved by the breach. Polymerization produces a solid, which does not 'jet' in a 'cloud'. In any case the part of polymerization causing the alarm here is that it is exothermic -- it is the cause of the otherwise-unexplained heat excursions in the car(s). The result of the breach is a typical boiling-liquid (the monomer being a liquid under pressure even at the heat extremes observed) expanding-vapor (the monomer expanded very rapidly from a great number of nucleation sites in the liquid simultaneously, like overcritical water in a rocket-type boiler explosion or opening a shaken soda can) explosion -- the expansion being further accelerated by the intentional rapid ignition of the expanding plume. It was pretty clear from the drone video that the plume starts out white for what seems more than a second, and only as it begins to rise does it take fire. That not all the monomer in the plume ignited is clearly recognized from the reports of decontaminating the streams. It seemed evident to me that the blobs of monomer seen on the cold beds under cold water had fallen out of the plume at about that size, and sunk to the bottom on account of their greater density as they quickly reached thermal equilibrium. In my opinion, had the car been breached after the general manner of the PRD release seen in D-53, so the evolving plume was better shaped and amenable to flameholding ignition, there might have been better experienced 'carburetion' of the monomer in air, and combustion and pyrolysis might have occurred more completely. I think you'd still have the dioxin release question to address, though, among with all the other issues of a kludge response.
Euclid Look at the video starting at 7:15:55 where Mr. McCarty speaks. He describes an unburned, white plume jetting upward from a tank car during the burn-off, which he speculates to be polymerization.
I cannot get this to pull up due to AT&T bandwidth issues, but either you or Mr. McCarty have a major comprehension problem.
EuclidMr. McCarty wonders if this focused tight column of upward discharge’ appearing to include liquid, contains polymerizing vinyl chloride. He seems very concerned about this, apparently because it might prove that polymerization was under way, thus confirming the persisting question about that point prior to the burn-off.
Note that 'polymerization' inside the car would likely start at a number of sites -- that is sometimes called 'polynucleate initiation' because it starts at nuclei that have free-radical activity or otherwise induce enough polymerization to accelerate a local exotherm. That implies that there may be a certain amount of polymerized (probably fairly short-chain) "PVC" in that jet, perhaps enough that it acts as a slush rather than a true liquid, and to me it would follow that such material might get into the PRD mechanism or ports and make it leak when 'closed' -- or, as with the car that was seeping until it suddenly and alarmingly stopped, that enough solid poiymer was aggregating at the valve and port connections to clog them up.
What I wonder is this: Why there is no visible flame in this photo of the gaseous/liquid material rising after the burn-off has begun?[quote]As with any BLEVE not directly accelerated by prompt critical-mixture ignition, the expanding vapor will not be ignited until (1) it has been carbureted, if it does not contain some internal oxygen or other reactive substance, and (2) an adequate initiation source, a sustained spark, hot-surface contact, or flame, actually initiates the combustion reactions. One would not expect stabilized vinyl chloride to 'explode' on release, and of course any polymerization actively taking place under confined pressure and insulated temperature conditions would more or less promptly cease as the jet bled down the pressure and allowed more and more of the mass to contact very cold air, cooling further through expansion.
Since this was to be a 'controlled burn' -- whoever arranged the thing would have set up a defined method of ignition. This ought to be, if it isn't already, something for the hearing to focus on intensely. It may be that the presumption was to use some sort of spot pyrotechnics or flameholding device at the periphery, and 'rely' on entrainment carburetion and heat transfer in the blackening (and therefore thermally much more conductive, as at Flixborough) to accomplish the desired ignition of 'all or substantially all' the monomer.
I am neither a chemist nor a hazardous-materials specialist -- but it seems very clear to me from what I do know that reasonable atomization, then reasonable carburetion, and then assured full ignition in a cloud generated by ad hoc shaped-charge breaching -- and remember that the objection to hot-tapping the cars, something with minimal or no explosive involvement, was that even well before a 'critical' explosion situation, the cars weren't safe to approach for the necessary precise placement -- would be Not Very Damn Likely. And that one of the most obvious things that would occur would be surface-burning condensed globules of expelled vinyl chloride (with or without a 'salting' of polymerized and less-reactive but still combustible material) that would condense into the virtual equivalent of rain and find a happy home both on the cold, cold ground and in any handy bodies of water.
This raises the question of whether vinyl chloride would have been lifted by the rising thermal plume without ever being ignited.
In other words, with this improvised flooded combustion system used here, [is it] certain that there will be complete combustion of the vinyl chloride “fuel”?
[quote user="Overmod"]
Euclid Mr. McCarty wonders if this focused tight column of upward discharge’ appearing to include liquid, contains polymerizing vinyl chloride. He seems very concerned about this, apparently because it might prove that polymerization was under way, thus confirming the persisting question about that point prior to the burn-off.
That the discharge is liquid monomer can be determined from the flow characteristics. The clouds are likely vaporized monomer becoming visible, just like water vapor from ''steam', by entrainment of the edges of the released jet in the surrounding cold air.
What I wonder is this: Why there is no visible flame in this photo of the gaseous/liquid material rising after the burn-off has begun?
As with any BLEVE not directly accelerated by prompt critical-mixture ignition, the expanding vapor will not be ignited until (1) it has been carbureted, if it does not contain some internal oxygen or other reactive substance, and (2) an adequate initiation source, a sustained spark, hot-surface contact, or flame, actually initiates the combustion reactions. One would not expect stabilized vinyl chloride to 'explode' on release, and of course any polymerization actively taking place under confined pressure and insulated temperature conditions would more or less promptly cease as the jet bled down the pressure and allowed more and more of the mass to contact very cold air, cooling further through expansion. Since this was to be a 'controlled burn' -- whoever arranged the thing would have set up a defined method of ignition. This ought to be, if it isn't already, something for the hearing to focus on intensely. It may be that the presumption was to use some sort of spot pyrotechnics or flameholding device at the periphery, and 'rely' on entrainment carburetion and heat transfer in the blackening (and therefore thermally much more conductive, as at Flixborough) to accomplish the desired ignition of 'all or substantially all' the monomer. I am neither a chemist nor a hazardous-materials specialist -- but it seems very clear to me from what I do know that reasonable atomization, then reasonable carburetion, and then assured full ignition in a cloud generated by ad hoc shaped-charge breaching -- and remember that the objection to hot-tapping the cars, something with minimal or no explosive involvement, was that even well before a 'critical' explosion situation, the cars weren't safe to approach for the necessary precise placement -- would be Not Very Damn Likely. And that one of the most obvious things that would occur would be surface-burning condensed globules of expelled vinyl chloride (with or without a 'salting' of polymerized and less-reactive but still combustible material) that would condense into the virtual equivalent of rain and find a happy home both on the cold, cold ground and in any handy bodies of water. This raises the question of whether vinyl chloride would have been lifted by the rising thermal plume without ever being ignited. With a little (relatively rudimentary) analysis, you could figure out how the temperature would reduce on expansion into cold ambient, and how the driving pressure tending to lift the vinyl chloride against its own mass would decrease in time and space. While those are BLEVE kinetics, they aren't yet complicated by ignition through the cloud and subsequent release and re-absorption of radiant heat. To answer the direct question: it would have paddled condensing monomer over a substantial area, following the projection of streamlines I see pretty clearly in the first second or so of the drone video of the controlled release. Now, the actual fallout plume might have been different in shape, or something else might have ignited the cloud or part of it randomly, and there'd probably be a hell of a lot more ground contamination requiring digging up and eventual pyrolysis. I can't imagine anyone, anywhere, who was part of a trained and responsible incident command to order something like that to be done. Perhaps someone like Tree might comment on what sort of triage assessment would have justified it. In other words, with this improvised flooded combustion system used here, [is it] certain that there will be complete combustion of the vinyl chloride “fuel”? No. Hell no. In fact even a polite answer expressing how unlikely that would be would not fly on a family-friendly forum without a great deal of circumspection and self-control I no longer have concerning this aspect of the East Palestine accident.
With a little (relatively rudimentary) analysis, you could figure out how the temperature would reduce on expansion into cold ambient, and how the driving pressure tending to lift the vinyl chloride against its own mass would decrease in time and space. While those are BLEVE kinetics, they aren't yet complicated by ignition through the cloud and subsequent release and re-absorption of radiant heat. To answer the direct question: it would have paddled condensing monomer over a substantial area, following the projection of streamlines I see pretty clearly in the first second or so of the drone video of the controlled release. Now, the actual fallout plume might have been different in shape, or something else might have ignited the cloud or part of it randomly, and there'd probably be a hell of a lot more ground contamination requiring digging up and eventual pyrolysis. I can't imagine anyone, anywhere, who was part of a trained and responsible incident command to order something like that to be done. Perhaps someone like Tree might comment on what sort of triage assessment would have justified it.
No. Hell no. In fact even a polite answer expressing how unlikely that would be would not fly on a family-friendly forum without a great deal of circumspection and self-control I no longer have concerning this aspect of the East Palestine accident.
EuclidI assume that a 100% destruction of the vinyl chloride would have required the use of a sophisticated technical incinerator designed and built for the purpose.
I think the operating assumption -- we're unlikely to have truly candid testimony on this, if so, for obvious reasons -- is that the vinyl chloride was being treated like a comparably low-boiling volatile hydrocarbon subject to BLEVE conditions. The internal boiling action would break up the ejected mass of material, the heat would rapidly expand it, the air would thoroughly carburete the resulting vapor and finely-divided liquid, and the propagating combustion heat would finish the job of volatilizing and surface-burning any remaining droplets in the cloud.
What actually happened, I think, is that the cloud 'quenched' early, and ejected a considerable amount of fairly large droplets that 'went out' too early, or were only surface-burning as they fell back down to ground. This is a different mechanism than what I think you're imagining, a huge 'fallout plume' drifting downwind with vinyl chloride, well, falling out of it as it cooled and condensed. (It remains to be seen what the actual fallout pattern with time after the breach is mapped to be.)
The correct way, really the only correct way to have handled this was to contain the vinyl chloride. That is what the 'hot-tapping' would have accomplished: reducing the internal pressure by pumping out and recovering a substantial amount of the vinyl chloride (any polymerization decreasing as the pressure was relieved) until the cars could be more safely approached and the remaining material extracted or passivated.
Overmod ... The correct way, really the only correct way to have handled this was to contain the vinyl chloride. That is what the 'hot-tapping' would have accomplished: reducing the internal pressure by pumping out and recovering a substantial amount of the vinyl chloride (any polymerization decreasing as the pressure was relieved) until the cars could be more safely approached and the remaining material extracted or passivated.
...
You seemed to have changed your thoughts on the general advisability of hot tapping in this situation since your July 14 post.
MidlandMikeYou seemed to have changed your thoughts on the general advisability of hot tapping in this situation since your July 14 post.
My problem is that I was raised with Boy's Life-style stories about the heroic exploits of Red Adair. That sort of outfit would have figured out some way to hot-tap the cars "enough" to avoid the need for the breach... right???
Meanwhile, we try not to judge the people on site, working with the information they had, and SOMEHOW deciding on an awful approach which left NS looking like an expedient, public-be-damned, incompetent outfit. I am beginning to see how this was a comedy of communication errors once the consultants got scared off attempts to set up for hot-tap. For example we see Wood go into a meeting, say to incident command that the consultants say it's unsafe to hot-tap and it looks from the temperature spikes that we'll have to breach before the safety consequences get much, much worse... and then have to leave that meeting to go talk to the NTSB people. While incident command gets a sort of target fixation on the expressed 'necessity' of a breach as expressed... now not one, but all five...
I would imagine that the five steps of strategic planning got a workout:
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