# Casting Tank Explosion...



## ElMostro (Oct 4, 2012)

I was watching "Sons of Guns" last night and they had an episode on trying to explode a propane tank with a bullet,  they actually shot a bullet through the tank and made a hole in it and all it did was release the propane but never exploded.  I don't know how thick those tanks are and the psi they are at but...

So it got me thinking, since the topic of "exploding pressure pots" pops up here every once in a while...has anybody seen documented proof of a paint pressure pot actually exploding.  Now, I don't mean a tank blowing the seal and tipping over or lids coming off under pressure bec they were not secured properly, what I am looking for is an actual tank explosion where the metal failed while under pressure.

Eugene.


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## PTsideshow (Oct 4, 2012)

It isn't the metal of the tank that causes the problems, and exploding isn't the proper word since there is no material to ignite rapidly and cause an explosion! it is one of the draw backs of the language. That we tend to describe something that more readily be called a catastrophic failure! the problem is when you have the lid come off propelled by 80 pounds of air pressure. It sure seems like i8t exploded when it hits you and you can be still dead as if some explosive charge, went off. Also the little bits of pipping and other accessories that are on the lid become flying shrapnel.
As to the propane cylinders, there is a reason why they are called LPG bottles Liquid propane gas. It will under certain conditions explode. but a bullet punching a hole in the wall they are quite thin. And the pressure is higher than used in the casting/paint pots. But not as high as in some welding gas cylinders. My mind is drawing a blank as to what the cylinder pressure is since they are sold by weight of the LPG.
The explosive limits in air are 2.1%-9.5% mixture.

With the big rig trailers and train cars the problem is BLEVE google it and they have a ton of videos. For those that don't care to. It is a _boiling liquid expanding vapor explosion_ is an explosion caused by the rupture of a vessel containing a pressurized liquid above its boiling point.

:clown:


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## Russianwolf (Oct 4, 2012)

mythbusters shot a couple propane tanks also. They weren't able to get a fiery explosion because the bullet wasn't causing a spark. Not spark, no ignition. They even tried tracer rounds. They could punch through, but no boom. Forget what they did to finally get a boom.

You don't need something to ignite to get an explosion though. Any internal energy source (compressed air) can cause an explosion. All you need is for the container to fail due to that energy. Think of a tire exploding.


If a paint pot is 12 inches in diameter, at 50psi that's 113 square inches and 5650 pounds being exerted on it. Nearly 3 tons of pressure trying to send the top flying. About the weight of my Suburban.

Use Caution and DON'T exceed the rated PSI.

The clamp welds are the most likely place for failure in the pots. That and in the case of the HF pot, the clamps slipping over the rim of the lid (I like the design of the Grizzly pot a lot better, but it involves more welds).


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## edicehouse (Oct 4, 2012)

DAMHIKT, but a home brew kit that uses corn......   You have to make sure the cap is on, cuz it will go flying when you are heating the mash up.


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## Fred (Oct 4, 2012)

edicehouse said:


> DAMHIKT, but a home brew kit that uses corn...... You have to make sure the cap is on, cuz it will go flying when you are heating the mash up.


 
And the reason being for the explosion ... the open flame (source of ignition) under the mash pot!

Otherwise it is just a sudden and violent release of high pressure which will surely get anyones attention that just happens to be nearby.

The best thing to do when dealing with any pressure device is DO NOT EXCEED THE MFG.'S RECOMMENDED PRESSURE which should be well marked on the tank. IF one decides that they know more than the manufacturer ... well, in my book they get what they deserve usually.


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## toddlajoie (Oct 4, 2012)

LPG pressure in the tanks varies depending on temperature, as it is in liquid form, around 50psi at 32 deg F, 100 psi at 60 deg F, and a bit over  150 psi at 100 deg F. I've seen people shoot the tanks with flares nearby to ignite the vapor. Doing this with full tanks is, in my opinion, idiotic, as the amount of vapor from a full tank is huge. If you want to try it, use nearly empty tanks. The liquid nature is a great example of why pressure guages are useless on these tanks. As long as there is liquid left I the tank the pressure will remain constant (assuming temp stays constant) but as soon as there is no more liquid, the pressure will drop fast.

As for pressure metal failing, I'm pretty sure any reasonably manufactured pot will have weak points in the design ( fittings, weld joints,etc) that will fail long before the metal will. I have seen fire extinguishers and scuba tanks where the metal failed, but with them the one fitting is designed to exceed the metal limits, and all the failures were caused by static testing, which involves intentionally exceeding working pressure by a significant margin, to be sure that a tank filled to working pressure can handle reasonable rises in temperature.


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## Smitty37 (Oct 4, 2012)

I agree with Mike on this one - The definition of explode is --- Burst or shatter violently and noisily as a result of rapid combustion, decomposition, excessive internal pressure, or other process,.
​The definition I learned in my youth related to explode is that the energy causing the bursting is from the inside moving outward  as opposed to implode where the energy is from the outside moving inward....​


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## ElMostro (Oct 5, 2012)

Ok so I'll rephrase the question; has anybody seen documented proof of a paint pressure pot actually having a catastrophic failure?  Again, blowing the seal and tipping over or lids coming off under pressure bec they were not secured properly don't count, what I am looking for is an actual tank failure where the metal failed while under pressure.  

I agree that the week point could be the areas where the clamps are welded but I am thinking that if the welds failed it would crack and their will be a release of air through the crack but as for the tank coming apart and pieces of metal flying around...I don't know.

Eugene


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## PTsideshow (Oct 5, 2012)

I believe it was Curtis had some trouble with one and there was another thread about the lid lid coming off and just missing somebody else. I'm pretty sure it was on this forum. 
http://www.penturners.org/forum/f43...led-me-63203/?highlight=pressure+pot+failures

http://www.penturners.org/forum/f43/catastrophic-pressure-pot-failure-my-wife-almost-became-widow-

51588/?highlight=pressure+pot+failureshttp://www.penturners.org/forum/f43/blew-up-44180/?highlight=pressure+pot+failures

These are the 3 easiest to find!
:clown:


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## ElMostro (Oct 5, 2012)

PTsideshow said:


> I believe it was Curtis had some trouble with one and there was another thread about the lid lid coming off and just missing somebody else. I'm pretty sure it was on this forum.
> http://www.penturners.org/forum/f43...led-me-63203/?highlight=pressure+pot+failures
> 
> http://www.penturners.org/forum/f43/catastrophic-pressure-pot-failure-my-wife-almost-became-widow-
> ...



I had seen Curtis' post on his pot incident but he stated that the failure was due to the clamps slipping bec of the "pot saver " modification he did to it, ....agree that had the lid hit someone it could had been catastrophic but it was not a pot failure it was a clamp slipping and the lid coming off under pressure. 

On Paladin's event I read through the thread when it first came out but not enough info to establish the cause...and its another lid flying off so there could be a number of operator actions that can lead to that.

Eugene.


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## dankc908 (Oct 5, 2012)

I dunno but, yesterday, my 12-year old mouthed off to my wife.  The 'explosions' described above were nothing compared to what happened next!  

Dan


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## maxwell_smart007 (Oct 5, 2012)

Explode, by definition, just means sending energy outward. The noise, bang, and fireball are just our version of what it 'should' look like.  Any violent  reaction that pushes outward is by definition an explosion.  (Ex - meaning 'out') - so a breached lid shooting across the room is an explosion of energy.  

However, other than semantical, is there a real difference between a pot shooting the lid across the room at a velocity enough to maim or kill, or a breach of the metal? 

In any system, the failure will be at the weakest point.  A clamped on top will be weaker than a smooth continuous metal pot, one would think.  

Regardless, in the case of a failure, the issue would be the flying metal bits - either the top, or the side, makes no matter to the person in front of the pot.


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## ElMostro (Oct 5, 2012)

maxwell_smart007 said:


> is there a real difference between a pot shooting the lid across the room at a velocity enough to maim or kill, or a breach of the metal?



I'd say there is a big difference bec if the lid comes flying off it could be a number of things from improperly securing the lid, deficient clamps etc where operator error may play a role, if on the other hand the pot fails bec the metal cracked or a weld gave way then that would very likely be a manufacturing defect unless of course the tanks was subjected to a drop or some external force that caused the crack.


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## Gilrock (Oct 5, 2012)

That's why I like the design on my C.A. Technologies pressure pot.  I've seen the Harbor Freight pot in the store and compared to that mine is built like a tank.  Even looking at the Binks tanks they don't have the type of safety catches on the latches that mine has.  It takes several turns of the wingnut before the washer is able to lift up over the metal hooks allowing the latch to swing down.  Anyways I don't go over 60 lbs so I'm not really stressing it that much.


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## Smitty37 (Oct 5, 2012)

ElMostro said:


> maxwell_smart007 said:
> 
> 
> > is there a real difference between a pot shooting the lid across the room at a velocity enough to maim or kill, or a breach of the metal?
> ...


That's a difference more apparant then real.  If a pot fails and sends flying objects where flying objects ought not to be, it matter's little why.  The why is only useful to help prevent it from happening again.  Not being an expert on pressure pots, having only used a pressure cooker a couple of times for canning vegitables I would still venture a guess that they do not fail often due to the skin rupturing since normally there are fittings attached where the attatchment will be weaker than the skin and they will fail at the weakest point.


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## InvisibleMan (Oct 5, 2012)

Gilrock said:


> That's why I like the design on my C.A. Technologies pressure pot.  I've seen the Harbor Freight pot in the store and compared to that mine is built like a tank.  Even looking at the Binks tanks they don't have the type of safety catches on the latches that mine has.  It takes several turns of the wingnut before the washer is able to lift up over the metal hooks allowing the latch to swing down.  Anyways I don't go over 60 lbs so I'm not really stressing it that much.



I have the same one, and I agree.  I can't see how the lid could ever fail on that thing.

That said, the pressure relief valve on mine was junk from the start.  It leaked with very little pressure.


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## Russianwolf (Oct 5, 2012)

InvisibleMan said:


> Gilrock said:
> 
> 
> > That's why I like the design on my C.A. Technologies pressure pot.  I've seen the Harbor Freight pot in the store and compared to that mine is built like a tank.  Even looking at the Binks tanks they don't have the type of safety catches on the latches that mine has.  It takes several turns of the wingnut before the washer is able to lift up over the metal hooks allowing the latch to swing down.  Anyways I don't go over 60 lbs so I'm not really stressing it that much.
> ...


 The Grizzly pot I got looks to be a very similar setup. In fact I can't tell the difference between it and the CAT 51-204 other than the mixer on the Griz is manual. Even the ball valve provided look the same. lower rating though.


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## mikespenturningz (Oct 6, 2012)

And lets not forget that the HF pot that the lid came off had been modified! My HF pot has a lip on it and I would rather doubt that as long as I do my part right that I would not have to worry about the clamps slipping, it simply cannot happen if you use it right. Also the manual for my HF pot has the max pressure rating of 80psi! I use about 60 because I am a chicken!


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## PenMan1 (Oct 6, 2012)

I had a HF pot rated for 80 psi blow apart at the "seam" at less than 50 PSI. I guess you could call the hole in the Sheetrock from the small metal shards from the pot and the splinters from the mold rack that disintegrated into "toothpicks" an explosion. The "boom and thud" that blew all of the mica pearls on a shelf a distance of about six feet cause enough noise to prompt neighbors to call and ask if I was shooting my acetylene tater cannon toward there house. It may be a matter of semantics, but I call this an explosion. Had I not just walked out of the shop, I'm SURE that I would have been injured.

There is NO recourse for this even though the pot failed. It had been modified from its intended design (paint sprayer) and into a dangerous modification. Explosion or not, I'LL NEVER MODIFY a HF TOOL AGAIN!


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## ElMostro (Oct 7, 2012)

PenMan1 said:


> I had a HF pot rated for 80 psi blow apart at the "seam" at less than 50 PSI. I guess you could call the hole in the Sheetrock from the small metal shards from the pot and the splinters from the mold rack that disintegrated into "toothpicks" an explosion. The "boom and thud" that blew all of the mica pearls on a shelf a distance of about six feet cause enough noise to prompt neighbors to call and ask if I was shooting my acetylene tater cannon toward there house. It may be a matter of semantics, but I call this an explosion. Had I not just walked out of the shop, I'm SURE that I would have been injured.
> 
> There is NO recourse for this even though the pot failed. It had been modified from its intended design (paint sprayer) and into a dangerous modification. Explosion or not, I'LL NEVER MODIFY a HF TOOL AGAIN!



Andy, an event like this is actually what I am looking for but with the pics to back it up. I am not doubting you but if/when I share it forward the first thing I am going to be asked for is proof.
When you say "seam", where was that located on your HF tank?  I have 4 different brands of tanks and I looked at all of them just now and I cannot see a seam in any of them.  Was your HF pot a rolled sheet of metal that had a welded seam and that is what failed?  Did you happen to take any pics of the pot after the event?  You wouldn't happen to still have the pot?  When you say "metal shards" are you talking about the other metal components on the tank or metal from the main tank/lid?  How about the hole in the sheet rock, how big/small were the holes made by the metal pieces? Where they just embedded or did they go through the sheet?  Were the pieces sharp, blunt, and particular shape? The wood rack, can you tell if it broke bec of the "explosion" or when it hit the ground?  Was the rack made of wood, MDF or plywood?
Is there a thread here on IAP where you discussed this?  I can look at that and maybe some of the answers to the questions above are in there. 

And I agree, if a pot (any pot) fails and "explodes" it would be a hazard the problem I am having is finding a "documented" case that I can quote.

Eugene


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## ElMostro (Oct 14, 2012)

Andy, I sent you a PM on this.
Thanks, Eugene.


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