Hydrostatic testing air compressor tank

I've been in a few of those plants and refineries around there Tony, but it has been probably 10 years or so. We set welding procedures on every job and everything is 100% x-ray and for the most part we do a pretty good job of monitoring it all but that is not to say there will never be a problem. Occasionally we encounter a spec where the root bead is mandated to be TIG welded and this is mainly done to minimize the dross introduced into the piping on existing systems as opposed to most chemical plants/refineries using TIG due to high chrome alloy material. 99.9% of the stuff I deal with is high carbon steel with some occasional stainless steel. Many years ago I built a plant near the Canadian border during winter. Water was really not an option to hydrotest with so I used diesel instead. This turned out to be a very cost effective solution as we re-used the diesel over and over and did not have to worry with drying the system to a specified dew point afterwards. In the end we ran the diesel thru some really fine sock filters and used it in various equipment and even vehicles on the job and also used it to heat with in big smudge pot heaters. I bet there was less than a gallon spilled accumulatively and by far this was more environmentally friendly than having 20,000 gallons of glycol and water to dispose of.
 
I am around a little of the med gas piping systems in hospitals now days, and they are using a Nitrogen purge to minimize and oxidation on the inside of any connection. They don't do a lot of pressure testing beyond what they system is going to see daily. They just gage up for it and shut off the valves and wait a day to see if the gage holds. Nothing too special. And some of the guys doing the work I have to wonder about. Not sure I'd want them plumbing my house, although they hold medgas certs. They are only doing med-vac, oxy and med air piping though, nothing high pressure outside of the LOX tank outside and the phase converters related. But I believe their are different guys doing that part of it.

Good idea on the diesel use. At least there is very little waste to contend with.

Well, we have successfully drawn this topic off into some interesting directions! No hijack violations anyway. Not that we have any real rules on that.:nono:
 
One way of looking at this, is the energy released during a failure cannot be more than was used to pressurize the tank originally. The energy expended pushing down a handle of an arbor press isn't very much. If there were much air space inside, the pressure wouldn't rise when the handle was pushed down.
 
Back to the original subject. You can hook up a hand grease gun to the tank and pressurize it that way.

As to the rust....well....I'd probably not worry about it and/or see if one of those gas tank restoration kits from Eastwood might encapsulate it. In any case I'd not put too much time into it.

I cut apart a 80 gallon, high hour, commercially used, air tank and it was really nasty inside. Probably 1/8 solid gunk all over the inside with a good 3/8" of **** in the bottom. Funny thing was it seemed the oil soaked **** actually preserved the inside surface of the tank. Considering it was probably close to 1/4" plate with even thicker end bells it would have lasted me many, many years without a problem.

As to filters I'd look into th Motorgard filters and Ingersol Rand filters with big in/out ports. My son got all his from Amazon.com. It constantly amazes me what that place sells/brokers.
 
Next to old propane tanks, old compressor receivers are popular with smoker builders, so a lot of them get cut open after their useful life as a tank. And much of the rust is just a flaky buildup that really doesn't hurt anything.

I had considered the fuel tank sealant, just to give some protection from future water buildup. But only after dealing with whatever rust I can get rid of.

Alan is right. Until I was able to get virtually all the air out of the tank, I could depress the cylinder all the way easily with very little increase in tank pressure. However, once I got the air out, I could easily get it to the required 200 rated pressure of the tank. But not satisfied with that, I bounced a little of my weight to get it to a little over 300 psig. I had to be pretty quick, because of the cracked bushing leaking water.


NX, by the way, I was not trying to contradict or correct anything you said. I agree with you completely that pressure testing should only be performed by people with experience and education when it comes to high pressures. There is a real danger in any case that should not be ignored, and I was not implying that it should. My intention was only to enlighten our members to the method that I used successfully and safely to test an air compressor tank. And to warn them that perhaps this is something they should be concerned with, since we all love to play with our older equipment.
 
Tony Wells said:
Next to old propane tanks, old compressor receivers are popular with smoker builders, so a lot of them get cut open after their useful life as a tank. And much of the rust is just a flaky buildup that really doesn't hurt anything.

I had considered the fuel tank sealant, just to give some protection from future water buildup. But only after dealing with whatever rust I can get rid of.

Alan is right. Until I was able to get virtually all the air out of the tank, I could depress the cylinder all the way easily with very little increase in tank pressure. However, once I got the air out, I could easily get it to the required 200 rated pressure of the tank. But not satisfied with that, I bounced a little of my weight to get it to a little over 300 psig. I had to be pretty quick, because of the cracked bushing leaking water.


NX, by the way, I was not trying to contradict or correct anything you said. I agree with you completely that pressure testing should only be performed by people with experience and education when it comes to high pressures. There is a real danger in any case that should not be ignored, and I was not implying that it should. My intention was only to enlighten our members to the method that I used successfully and safely to test an air compressor tank. And to warn them that perhaps this is something they should be concerned with, since we all love to play with our older equipment.
Click to expand...

Tony, I never thought otherwise.....I just wanted to emphasis the inherent dangers. I wonder why there are no glass lined air receivers like the water heater tanks are typically done?
 
Re: rust removal on air compressor tank

Tony,
Any updates on the rust removal portion of your air compressor rebuild?
 
Not yet, Harry. Working on the pump now. I spotted another 2 stage 4 cylinder pump at a friends shop I may want to use instead. I looks nearly brand new. I will have to compare size. This one is only a 5, but I also have a 10 hp motor I can use if the other pump turns out to be able to handle it. When I settle on that, I'll return to the rusty tank. I will keep this thread updated.
 
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