Explosion at CF Industries

[scooterj]

Sorry, I had not read the news report. All I saw was where someone said tank truck. I'm sure that many don't realize that flowing inert gasses will create static electricity. A flammable gas leak can be ignited by the inert flow.

 

[TomTerrific]

I thought nitrogen was not flammable

Nitrogen is not flammable nor does it support combustion. It is used to blanket tanks with flammable liquids.

I can't give any credence to the claims about being fired for this and that without names, dates, and places. Didn't happen in the plants I worked in.

 

[Btl_Rkt_Sci]

Shure could be negligence. If the truck was not propperly grounded, static electricity could have been the ignition source.

When I said "negligence" I was referring to gross negligence. As in a safety issue that the plant was aware of but chose to ignore. Not a lapse in judgement or operator error.

 

[Dishonored]

My assumption...
The nitrogen was there to be used as a prurient for a tank. It much have been depleted or drained and waiting for repairs. The nitrogen is pushed in at a very high pressure and "purges" the flammable and combustible materials previously in it out. This gets the "LEL's" low enough for entry. The blow out was probably caused by over pressure do to, someone not paying attention or a faulty gauge.

It could be used for other things and could have happened another way. This is just my take on the situation.

 

[TomTerrific]

My assumption...
The nitrogen was there to be used as a prurient for a tank. It much have been depleted or drained and waiting for repairs. The nitrogen is pushed in at a very high pressure and "purges" the flammable and combustible materials previously in it out. This gets the "LEL's" low enough for entry. The blow out was probably caused by over pressure do to, someone not paying attention or a faulty gauge.

It could be used for other things and could have happened another way. This is just my take on the situation.

Do they vent this purge directly to the atmosphere? Wouldn't it go into a recovery unit of some sort?

If they purge a vessel with nitrogen, while the LEL might be OK, there wouldn't be enough oxygen to support life so special breathing apparatus would be needed for entry.

Hopefully, we will get more info.

 

[swagge1]

Here is the info I have. One of my bosses sons was injured by the overpressure. He took several stitches to the back and fractured 7 vertebrae. I got word today that he is doing fine and was released from the hospital. What was conveyed to me was that a liquid N2 truck was offloading N2 product into a tank. An operator shut a valve (likely off the discharge) causing an overpressure at the trucks pump which resulted in an overpressure and resulting line failure of the trucks offloading manifold. The operator was killed. If youve ever seen an Argon, N2, LOX, or other cryo truck you'll know that these trucks often have coils with thin radiator fins attatched to their bellies. Its my understanding that the overpressure destroyed the manifold and created a wall of shrapnel out of the metal fragments and fins. There may have been a small fire resulting from another product being spilled from line piercing or the trucks diesel tank catching fire.

 

[Dishonored]

Do they vent this purge directly to the atmosphere? Wouldn't it go into a recovery unit of some sort?

If they purge a vessel with nitrogen, while the LEL might be OK, there wouldn't be enough oxygen to support life so special breathing apparatus would be needed for entry.

Hopefully, we will get more info.

It normally is just vented into the atmosphere. In my experience.
Yes that is correct, you are only permitted entry so the proper equipment and certifications. I don't really know the proper term if there is one. We call it "going inert."
I have never done it but my father has. It is performed a good bit when you are in the catalyst field.

 

[buttanic]

I have been involved in unloading many nitrogen trucks at Dow St. Charles. Normally all I did was show the driver where to connect his unloading hose and he did the rest of the unloading. Seems this might be the truck driver's error and not the fault of a CF employee.

 

[gmshooter]

Possibly if they were changing catalyst in a reactor they were using the truck to keep the reactor inert. They usually have another trailer that has a pump with a open flame. They can flow whatever cubic feet the customer wants. We use a psv on the line to prevent over pressuring. Prayers for the family.

 

[CEHollier]

You would think with this scenario being a possibility there would have been pressure sensors or some type of safety system to prevent such an overpressure. Or a pressure safety valve to release the gas. Edit - gmshooter I agree with the PSV in line.

 

[swagge1]

EDIT: New information is that it was the plant manifold that was ruptured, not any equipment on the truck. Also the injured guy has 5 fractured vertebrae and not 7.

 

[CEHollier]

EDIT: New information is that it was the plant manifold that was ruptured, not any equipment on the truck. Also the injured guy has 5 fractured vertebrae and not 7.

Thanks for the update. I have been out of the PetrolChemical industry for a long time. But a PSV on the pump discharge would prevent an overpressure.

 

[SVTFreak]

Geesh, the amount of guessing and conjecture here is incredible. You dudes are as bad as the media with this shirt.

 

[TomTerrific]

EDIT: New information is that it was the plant manifold that was ruptured, not any equipment on the truck. Also the injured guy has 5 fractured vertebrae and not 7.

So it was equipment with too much pressure that exploded rather than pressure caused by a chemical reaction/combustion?

The tank truck involved would have been pressurized gaseous nitrogen rather than liquid N2?

We have a lot of chem plant experience on this list and I appreciate all y'all's input.

 

[sandman7925]

Vessels are overbuilt. Can't imagine the amount if pressure required to make one pop. I'd like to know when the last time the vessel and manifold was NDT'ed. But I'm sure that will be part of the investigation.

 

[soontobetwo]

I have been working 20+ years with cryogenic gases in chemical plant operations. Sounds like catastrophic fAilure of a psv or could be low temp failure of carbon steel piping. Either way there should be pressure relief devices or low temp protection. The liquid n2 trucks have devices to protect their piping. This has to be bad preventive maintenance or piping testing.
My prayers go out to the families. It's really sad that it takes accidents like these to implement new safety systems. I just don't believe the safety moniker that all accidents are preventable. I am a realist and believe s*** happens.

 

[jmcrawf1]

Geesh, the amount of guessing and conjecture here is incredible. You dudes are as bad as the media with this shirt.

At least LE isn't the only job people think they can monday morning quarterback on here

 

[Dishonored]

I would believe several of us have enough experience in this field to offer reasonable explanations as to what happen. Doesn't mean our speculations were correct, just an educated guess to help with the questions being asked.

I do not have as many years experience as some I'm sure. I have been around it since I was a kid though, and now I'm involved in the process of it all for a living.