Compressor tank explosion

[royesses]

Just found this thread on the welding web safety forum. Thought this might be a good read for anyone wanting to work on older air compressors and see the damage they can cause.
http://weldingweb.com/showthread.php?p=455570#post455570

 

[Skin]

yes a good lesson indeed to drain your tank at least monthly and inspect new[old] tanks prior to installation. A ball peen hammer and a punch checking the integrity of the underside probably would of saved him from that injury.

Honestly i'd expect worse considering he was next to it.

not that it matters but from the color i'd guess that was an IR, not a craftsman. Craftsman are usually red with older ones being a silver.

 

[royesses]

Yes he is a very lucky man. A co-workers 3 year old daughter was killed in a similar explosion back in the early 70's when I lived in California. Rust was the cause in that one.

 

[atari]

Holy smokes!

 

[rockchucker]

Whooooooooly ****.

Did you see the last post in that thread though with the Cast Pump?

Man o man...A life was lost in this Cast Pump Detonation. RIP

May as well post the pics up for people to see here also...

 

[Kev442]

There is the main reason I put a 125 PSI pressure switch on mine when I went through it. 155 PSI is pretty scary sounding on a 30+ year old compressor. When I bought it, I cycled it several times to 155 while standing a loooong ways away from it!

 

[mrb]

i wonder if someone welded the leg back on that tank............

 

[Pro-Painter]

That is why I check my blow off valve almost daily. Compressed air is dangerous even at low PSI levels.
Ive got a close friend that worked at a truck stop garage changing truck tires and he had a recap blow up wile putting air in it and it took off his nose. No kidding, he has no nose. He only has what little skin they could save and a large hole in the center of his face. He looks like Dan aykroyd in the movie "Nothing but trouble" It also took out his front teeth, and caused him to bite off the tip of his tongue.

 

[DrkMtnDew]

WOW. that was one hell of a bang. glad those pic were posted. i got an old compressor. best make sure the blow by is still operative.

 

[Lhorn]

That is why I check my blow off valve almost daily.

For those of us who haven't tested ours, how do you test it?

 

[bmwpower]

For those of us who haven't tested ours, how do you test it?

Pull it open. Does it purge?

 

[blue dog]

That man is a very lucky human being. Now that cast pump, wow

 

[Lhorn]

Pull it open. Does it purge?

Again, stupid question....I'm guessing the blow off valve is designed to activate at a specific PSI? Anyone know what that is? Just pull up on the valve and it vent's? Does the valve have a spring or something that will close the valve when I stop pulling up on it? After looking that those pictures, I'm gonna wear an umpire's chest protector, put a metal collender on my head and hold a tennis racket to shield my face when I try this.

 

[Skin]

yes, pops open at a preset pressure then closes on its own once it hits a safe level. Looks like this

Usually found on the tank, around the pressure switch, and occasionally on the head of the pump. There could be more than 1 depending on the CFM. The point is if the pressure switch malfunctions the valves open automatically and stop the tank from filling until something gives.

Yank the ring and it will give you a gust of air, quite loud as it purges the charged tank. Its spring loaded so when you let it go it will close. Its no different than opening the drain valve.

For the record antique compressors did not have them. Neither of mine do anyway.


Not entirely sure what all the discussion about relief valves is about though. A malfunctioning relief valve clearly was not the case here. Even a compressor rated for 100psi should be able to take 150 with no problem. On smaller compressors they're often rated by the pump output rather than the tank anyway. His issue was really severe rust in the tank belly. All the relief valves in the world wouldnt have stopped that that tank from failing at one point or another.

 

[oldtools]

The blow off valve is set to vent at certain pressure like 175 psi, but the tank can still blow at say 150 psi before the air get vented. Compressed gas has energy equal to the pressure multiply by the volume. So an 18 gallons at 150 psi has energy equivalent to 3% of a stick of dynamite.

Don't forget that pointing pressurized gas at your skin can kill you also (the air enter through your skin and then into your blood stream).

Anybody know how to check the condition of the compressor tank (internally)?

 

[tjmonsen5]

wow, that is scary!!!

 

[CBradio]

Anybody know how to check the condition of the compressor tank (internally)?

this. If you dont have one this size, take off your drain/outlet/any orifice and get a boroscope.

 

[Cantause]

Small ultrasonic thickness gauge can also be used to check sheet metal thickness...

I think that companies which test compressed gas vessels fill them completely with water, then plug a source of compressed gas or water with a regulator set on the max tested pressure of the tank. This way in case of failure there is almost no burst (for low pressures as used in our compressors) as water don't store a lot of energy when compressed compared to air.
I guess it's the same in the US than in Europe, here professionals must have their pressure vessels checked periodically by this kind of companies...

 

[stricht8]

And that was a tiny compressor. Could you imagine what damage a 60 gallon would do?

 

[fordbroncodave]

NOOOOOOOOOOOOOOOOOOOo the ice cream drum sticks are melting

 

[stricht8]

I drain my compressors every time I use them but the water is still tinged with rust. Should this be a concern? Do these tanks every get an internal coat of paint?

 

[kc-steve]

Just found this thread on the welding web safety forum. Thought this might be a good read for anyone wanting to work on older air compressors and see the damage they can cause.
http://weldingweb.com/showthread.php?p=455570#post455570

Are you "Moonrise" over at WeldingWeb? I kinda like the folks over here better. Yeh there are some good people over there too, including Mike (the OP), but this place I think is far less stressful if you know what I mean.

Steve

 

[z28snksknr]

i wonder if someone welded the leg back on that tank............

I was waiting for this. In fact, I only looked at this thread to see how long before someone made reference to that.

 

[royesses]

Are you "Moonrise" over at WeldingWeb? I kinda like the folks over here better. Yeh there are some good people over there too, including Mike (the OP), but this place I think is far less stressful if you know what I mean.

Steve

No i'm not moonrise. I like GJ and welding web. Both have knowledgeable people and very interesting threads.

 

[kywildcat]

I'm sure I will be standing back away from mine while it fills for a little while, and it's brand new....but I will always think of this now.

 

[Theloniousmonk]

i wonder if someone welded the leg back on that tank............

 

[Skin]

I drain my compressors every time I use them but the water is still tinged with rust. Should this be a concern? Do these tanks every get an internal coat of paint?

No conern, its normal. You may even hear little pieces of rust shoot out depending on what kind of valve you have installed. They are usually not treated but you can have it done. Not worth it in my opinion. If you're that concerned simply buy a new compressor every 20-30 years.

 

[fordbroncodave]

we actually use to own that exact same sears compressor. dad traded it to the mac tools guy to pay off some of his account. ours was spotless with no external corrosion

 

[waltmcq]

I almost crashed my van today cuz the ole drum brakes locked in the rain

 

[Kurt4440]

I purchased a compressor from Sears ~28 years ago that looks identical to the one in the pictures. I'll talk to you guys later, I have to check something.

 

[Roots]

Small ultrasonic thickness gauge can also be used to check sheet metal thickness...

I think that companies which test compressed gas vessels fill them completely with water, then plug a source of compressed gas or water with a regulator set on the max tested pressure of the tank. This way in case of failure there is almost no burst (for low pressures as used in our compressors) as water don't store a lot of energy when compressed compared to air.
I guess it's the same in the US than in Europe, here professionals must have their pressure vessels checked periodically by this kind of companies...

Tis true, on both accounts. However I'm not aware of the testing requirements on pressurized steam vessels extending to pressurized air vessels, at least in the United States.

 

[sweetk30]

were i use to work i toldthem thay need a new tank years ago. the drain hole at the bottom. ( vertical tank ) keeps pluging up with huge rust chunks.

 

[madamd]

arent all the new tanks made in china now? thin metal + untreated shell = ticking time bomb?

 

[littletoes]

OK, I'm going to try this again....

Had this big long post on the safety of an air compressor, lost it all......


Lets start,

The "blow-off" valve is a SAFETY RELIEF VALVE. Its job is to protect the TANK from OVER PRESSURE.

In other words, if the pressure switch fails, and your compressor tries to keep pumping to the point of a possible rupture, the relief valve is suppose to "blow", thus preventing the tank from bursting.

Sure, it can FAIL, thats why you should test it on occasion. At least once a month.

Does the same basic job as your T & P valve on your Hot Water Tank, only your HW tank will do Much More Damage......have you ever checked it????

 

[littletoes]

That same Safety Valve is NOT there to protect your tank from RUST. And it won't work at all if its bad, and you have never checked it.

Now, if the tank is rusting from the inside, because you have never drained it, or don't drain it enough, you could have a problem.

Again, every Safety Relief valve has a rating, as does your tank. BOTH are stamped somewhere on them.

Usually a big 4"X4" stamping on your compressors tank, and it will say the MAWP of the tank, and at what temp. High temps lower bursting pressure. You see, your compressor tank is a pressure vessel, and this stamping is the rating.
Your Relief Valve should never have a higher relief pressure than your tank. I hope you can imagine why!

Sure they can be changed, they are usually 1/4" pipe threads, unless larger. Adjustable versions are not allowed by inspectors....but hey whoes inspecting yours???? Hope you don't think thats enough reason to install one....

 

[littletoes]

I would bet that tank had been leaking at the weld a slight bit well before it split.

That or the guy screwed with the pressure switch, and over pressurized the tank, AND gagged the rv if there was even one on it.

Guys do **** like that all the time.....

 

[porschedude996TT]

Holy ****, I used to have one of those compressors! I bought it in 1983 or so. Used to have a bunch of water everytime I used it to prep and paint cars. Ouch!

 

[littletoes]

Why sure, if theres water in the "air" it collects in the tank.

 

[Shadowdog500]

I have that same craftsman compressor. Bought it around '85. I don't ever recall mine going much higher than about 120 PSI even with it turned all the way up. I also wonder if, in addition to the rust, if the pressure switch failed to turn the pump off at a lower pressure like mine does. I also agree that rust in the bottom of the tank scares me some because even with regular draining the tank has to rust out eventually.

I do check the pressure valve occasionally. I also open the one in my hot water heater whenever I pass it(a few times a year). Saw some photos of a hot water heater that exploded, and it looked like a nuclear bomb went off.

Here is a video:
Chris

 

[littletoes]

Water expands one thousand six hundred times to become steam. One pound of water, makes one pound of steam.

Usually the bottom goes first....so you have a rocket, in essence.

Don't check 'em....I need the work.