How dangerous is a compressor air receiver failure?

Hi, I have an air compressor that is now over 25 years old. It is a two stage compressor, air receiver about 15 inch diameter and 3 1/2 foot long,
now running at 100 psi, but the two stage design has allowed me to run it at 175 psi in the past for greater air storage.
The air receiver is showing signs of corrosion internally, and I've been wondering what happens when it gets to the point of leaking at a deep rust pit along the bottom of the tank. I realise I can hydrostatically test it, but I am wondering if anyone has actually seen the results of one failing due to corrosion. I imagine it would not be like a steam boiler letting loose, but it may be worse than an air leak at a coupling.
Anyone have experience wih this?
regards,
John
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It might explode but more likely would just develop pinhole leaks. Compressors are cheap. Why take the risk?

at
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Hi Al, I'm not taking any risk, it will not run again until its either tested OK or replaced, I'm just interested to know if anyone has seen one fail. Although it's 25 years old, it's only had hobby use, and the compressor is high quality. At most I'll replace the receiver.
What caused me to ask the question was that I have been looking at new compressors and receivers, and the counter jumper at the local dealer told me that tanks don't fail explosively, so just run it till it fails. Just wondering if the guy was silly enough to loose a sale and give me advice that might kill me, or was he right?
regards, John

long,
it
rust
it,
failing
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wondering if the guy was silly enough to loose a sale and give me advice that might kill me, or was he right?>,
I personally have seen a tank explode, and let me tell, it's nothing short of spectacular. This was not an air compressor unit per se, but an old Norge refrigeration compressor mounted on some sort of tank that I bought from an an old junk monger when I was about 18. It pumped up to 175psi just fine. It was housed an open air shed and I turned it on one frosty morning to air up a tire. Twenty minutes later I heard it still running and I went out to the shed to turn it off. The thing exploded when I was about 15 feet from it, luckily having not yet rounded a corner to be in its direct path. The tank lauched out of the shop about 6' off the ground (much like the pictures of cruise missiles that we see today) and came to rest some 125' away. The rear end of the tank blew a hole through the back of the shed and somehow destroyed an adjacent interior wall also. The dust in the shop was impenetrable and took over 10 minutes to settle before I could see what happened.
Apparently moisture had frozen in the pressure cutoff and disabled it, causing overpressure. I would assume that "air compressor" tanks are engineered to fail in a less violent manner but don't know that for a fact. I do know that, but for the grace of God, had I been 5 steps faster that morning, I might not be sitting here today. Gary Brady Austin, TX
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: :I personally have seen a tank explode, and let me tell, it's nothing short of :spectacular. This was not an air compressor unit per se, but an old Norge :refrigeration compressor mounted on some sort of tank that I bought from an an :old junk monger when I was about 18. It pumped up to 175psi just fine. It was :housed an open air shed and I turned it on one frosty morning to air up a tire. : Twenty minutes later I heard it still running and I went out to the shed to :turn it off. The thing exploded when I was about 15 feet from it, luckily :having not yet rounded a corner to be in its direct path. The tank lauched out :of the shop about 6' off the ground (much like the pictures of cruise missiles :that we see today) and came to rest some 125' away. The rear end of the tank :blew a hole through the back of the shed and somehow destroyed an adjacent :interior wall also. The dust in the shop was impenetrable and took over 10 :minutes to settle before I could see what happened. : :Apparently moisture had frozen in the pressure cutoff and disabled it, causing :overpressure. I would assume that "air compressor" tanks are engineered to :fail in a less violent manner but don't know that for a fact. I do know that, :but for the grace of God, had I been 5 steps faster that morning, I might not :be sitting here today.
A tank that fails due to overpressure is a scenario that is vastly different from a tank that begins to fail at normal pressure due to corrosion. A sound tank that fails due to overpressure is _very_ likely to produce a spectacular explosion.
--
Bob Nichols AT interaccess.com I am "rnichols"

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They typically develop pinhole leaks but if the corrosion develops along a seam that decided to let go, the result is pretty spectacular. You have the same issues with a steam boiler at the same temperature and pressure excecpt the air tank is not running at 250 to 275 degrees F.
A new tank is $150 with wheels and a handle at McMaster, replace it if you feel uncomfortable. ASME rated tanks are better but more money. Similar story at Grainger.
john johnson wrote:

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A steam boiler is FAR more dangerous than an air tank.
While the vessel failure may occur at the same pressure, due to some structural weakness, there is a vastly greater amount of stored energy in the superheated water in the boiler than in a like volume of compressed air at the same pressure. It's the sudden, uncontrolled release of all that energy that does the damage.
Other issues include the tank being likely to rupture at a lower pressure due to the higher temperature of the boiler (and thus weakened materials), and the extreme injury that may result from scalding even if you're NOT hit with flying shrapnel from the explosion.
Yes, compressed air tanks can be dangerous, but boilers are far more so.
Dan Mitchell ========= Roy J wrote:

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john johnson wrote:

VERY dangerous to anyone who happens to be nearby! I have never witnessed a tank failure, but I've seen a couple that have burst. The horizontal tanks often get a line of corrosion at the lowest point, and burst open by violent unrolling of the wall. The tanks end up unrolled into a flat sheet. Some profs at the university where I work do some work as accident investigators, and I've seen these tanks in their pickup. There definitely are fatalities related to this.
Jon
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Mark that down as one more reason (other than the noise) to give the compressor its own shed out back.
But not nearly as dangerous as steam - the other reply claiming steam was similar does not understand steam. When a 175lb air tank blows, a certain volume of air (12x the volume of the tank, roughly), is released, period. That can certainly kill you if you're standing in the wrong place at the wrong time, but it's not much of an explosion.
When a boiler blows, not only does the vapor in the boiler expand from pressure to atmosphere, the water in the boiler expands by almost 2000 times as it flashes from water to steam. Not to mention the heat, scalding, etc. Which is why boilerhouses tend to have strong walls and weak roofs - if the boiler blows, the explosion will kill fewer people if it's channeled straight up.
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Hi, Thanks for the feedback everyone, I'll get it a new tank.
regards,
John
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replying to john johnson, KD wrote: Have a look at this video of air receiver failure captured by home security camera.
https://www.youtube.com/watch?v=KVP_A7eGYxw
Listen to the commentary and watch to the end to see photos of the remains of the air receiver. If I were you I would just buy another unit rather than run the risk of using a corroded pressure vessel. New ones are very affordable.
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On 01/05/2017 05:18 AM, KD wrote:

Look how the end caps separated cleanly off that thing. That wasn't rust. I'm worried now, better put mine on craigslist. Maybe Gummer will score it.
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wrote:

Or hover over it during each filling? <wink> I'd like to see all the edges of that tank to determine just what -did- happen to it.
If the guy's father hadn't been right next to it, it would have missed him altogether.

And weld it back together with his supreme 'trailer spare' welding feats. <gd&r>
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Larry Jaques wrote:

If you look close at the still images at 2:45-2:47 it sure looks like a new weld with the paint blackened and very clean edge. Straight in line with the air fitting at the edge of the tear. I'm wondering if it pin holed, they cleaned and welded it but didn't get proper penetration, and the tank tore apart in the HAZ. As for the end caps, that's common in a pressure vessel failure (actually intended as well) The metal tears away at the weld.
--
Steve W.

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On 1/6/2017 1:20 AM, Steve W. wrote:

It is fishy. I'd like to have my hands on the remains and find the bad spot. As one of the YouTube commenters said, it was likely an over-pressure situation with the pressure switch and pop-off both failing (or over ridden). I would expect rusty tanks to leak progressively until they're useless. It doesn't take much of a leak before the compressor is cycling too often and a hiss is noticeable.
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On Fri, 06 Jan 2017 10:47:50 -0500, Bob Engelhardt

The outside of the seam is painted, and it's old paint.

I think that may have been done later, removing the domes during cleanup.

Because the tank split straight at the seam, it does look more like an overpressure failure than anything else. Tears are usually more jagged and curved, not perfectly straight. Note the way it jumped straight up into the air, too. It appeared that the father was looking at it when it went, too. Perhaps he heard something and...
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Larry Jaques wrote:

No, I don't believe that. The compressor only jumped up a couple feet, and didn't knock the guy down. And, apparently, he survived. If the tank had let go at 120++ PSI, likely both of them would have been killed, one by being squashed against a wall or ceiling, and the other by flying debris.
Even small receiver failures are notoriously fatal, and the damage to the shop testify to the HUGE forces involved. These things do almost as much damage as an artillery shell. From the video, it seems that this one let go at well below 100 PSI. It was enough to flatten the tank, though, so more than, oh, maybe 25 PSI or so (And I'm no expert on the dynamics of rupturing tanks.)
Jon
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