csua.org/u/f89 -> pipeline.corante.com/archives/2006/03/08/how_not_to_do_it_liquid_nitrogen_tanks.php
About this Author Derek Lowe Derek Lowe, an Arkansan by birth, got his BA from Hendrix College and his PhD in organic chemistry from Duke before spending time in Germany on a Humboldt Fellowship on his post-doc. He's worked for several major pharmaceutical companies since 1989 on drug discovery projects against schizophrenia, Alzheimer's, diabetes, osteoporosis and other diseases.
jpg A colleague of mine forwarded a copy of an accident report from Texas A&M. It seems that in mid-January they had a bit of a blowout there, thanks to a big liquid nitrogen tank. Now, liquid nitrogen cylinders are normally fairly benign, as long as you don't freeze your external organs off with the stuff or leave the liquid sitting around where it can condense oxygen out of the air. But idiocy will find a way - note the regular cylinder on the right and the new, improved model next to it. These guys are usually equipped with pressure relief fittings, since nitrogen does tend to want to be a gas, and gases do tend to want to expand quite a bit. This tank, though, which seems to have been kicking around since 1980, had been retrofitted by a real buckaroo. Both the pressure relief and rupture disks had failed for some reason in the past, so they'd been removed and sealed off with metal plugs. Why it didn't blow long ago is a real stumper, but presumably people were taking nitrogen out of it quickly enough to keep things together. Not this time, though: at around 3 AM, things came to a head as the internal tank (these things are double-walled) expanded until it pressed against the outer one. That kept it from expanding anywhere else except on the ends, and as fate would have it, the bottom blew out first. The engineer's best guess is that this took place at around a 1200 psi load. It must have been quite a sight, although it's a damn good thing that no one was around to see it. I'll let the engineer's report take it from here: The cylinder had been standing at one end of a 20' x 40' laboratory on the second floor of the chemistry building. It was on a tile covered 4-6" thick concrete floor, directly over a reinforced concrete beam. The explosion blew all of the tile off of the floor for a 5' radius around the tank turning the tile into quarter sized pieces of shrapnel that embedded themselves in the walls and doors of the lab. The blast cracked the floor but due to the presence of the supporting beam, which shattered, the floor held. Since the floor held the force of the explosion was directed upward and propelled the cylinder, sans bottom, through the concrete ceiling of the lab into the mechanical room above. It struck two 3 inch water mains and drove them and the electrical wiring above them into the concrete roof of the building, cracking it. The cylinder came to rest on the third floor leaving a neat 20" diameter hole in its wake. The entrance door and wall of the lab were blown out into the hallway, all of the remaining walls of the lab were blown 4-8" off of their foundations. All of the windows, save one that was open, were blown out into the courtyard. No one seems to have heard the celebrations, but someone noticed that the building's water pressure had gone a little wimpy and went to investigate, which I'll bet was a real eye-opener. I get the impression that they're still trying to track down the Mr Fix-It who inadvertently rigged the tank for takeoff. The company engineer who came in to investigate noted that he's seen these kinds of "repair" jobs before, generally after they've powered through something.
The report suggests that the "repairs" on this tank were done at two different times. Also, the lab where this happened was a synthetic organic group - the destruction+flooding, which made it into the lab below and the departmental office, made for a hazmat problem. One of my friends in Chemistry suggested that we should have all grad students tour the destruction before it's repaired.
Sorry I missed the ping, Jim - it's probably buried in there with all kinds of wonderful offers for discount everything. I figured you'd have some more information on this, though. I told my wife, who did molecular biology for some years, about this one. so they stopped it up with metal plugs" she covered her eyes with her hands and started shaking her head.
I've heard all kinds of horror stories in the past about cylinders turning into rockets when the cap was broken, but this one takes the cake. Makes you wonder what kind of precautions the people take who work with superciritical liquid nitrogen.
Permalink to Comment 5 Dave on March 9, 2006 10:38 AM writes... I used to do a fair amount of NMR in grad school on an ancient Bruker 500 MHz spectrometer. This was a departmental instrument and there was no facilities manager at the time so that many different users were doing both the liquid helium and liquid nitrogen fills. Liquid helium can be tricky as it's easy to "overfill" and run your dewar dry so that you end up pumping in residual gas/air from the dewar along with condensed water/ice. This type of mistake was made often enough over the years to plug 3 of the 4 helium vents on the 500 with ice. So one fateful Friday afternoon, I sat down as a novice user to run a series of experiments over the weekend with one of the more senior students in my lab. We were calibrating pulse lengths, shimmming the machine and so forth and I thought the data looked horrible and that something must be wrong. I came in the next morning to process data to find one of the faculty disassembling what was left of the instrument. The layer of ice and snow covering everything in the lab tipped me off to the fact that the last helium vent must have plugged up. It had done so at 3am and caused the bore to be shot from the body of the 500 with sufficient force to go through the 2 floors above and into the ceiling 3 floors up. The moral of this and the A&M story: trust your instinct and don't take the word of those around you when they're obviously wrong because the results can be deadly!
Straight out of college I was working in a polymer lab for a great Dutch company. I was shown a video during a training session of an Argon tank that had fallen over, had the valve knocked off, and took off like a drunk torpedo. After completing the transfer, he pulled the flask from the N2 bath and noticed a bluish tint.
One of the things that's scary as head of a lab is not knowing what things like this may have been done without anyone bothering to tell you. Every now and then I'll be walking through the lab and I'll find that someone is doing something really weird (washing the toothpicks, for example - we reuse them, but all you have to do is autoclave them).
Permalink to Comment 9 Anonymous on March 9, 2006 04:55 PM writes... The awful truth is that this type of stuff happens (or is ripe to happen) all too often in academic labs. Frankly, the PIs have only themselves to blame for this sorry state of affairs. Lab violations were one of the items that was used to justify shutting down Pettit's lab at ASU-but that whole ordeal is worthy of its own post.
I did an apprenticeship at an industrial control systems manufacturer some 20 years ago. One of the things they did to scare us out of our tiny minds was to show us videos of typical industrial accidents.
BLEVEs (Boiling Liquid Expanding Vapour Explosions, also known as Blast Levelling Everything Very Effectively). The company has offices in Houston - maybe they could show some of the same videos at A&M (or take the opportunity to film some new ones)?
Schlumberger had a similar scare-the-s**t out of them film, only this was for workers doing well casing perforation with shaped charges. It's amazing what a shaped charge will shoot through when it goes off.
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