Public Service Message: Have you hydrostatic tested your air tanks?

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Erik the Awful

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You should have any air tanks you use in your shop hydrostatic tested every five years. In essence, it gets filled with water, pressurized to 150% of its rating, and the technician taps it with a hammer around every weld and fitting. If it's rusting inside, it'll crack, spew some water out, and it gets crap-canned.

If you think I'm some kind of pro at my home shop, I'm not. I just realized I really need to do this with my compressors. I have access to the hydrostatic test tool at work. I think I need to make a video...
 

454cid

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I recently saw a Youtube video where a guy had his compressor explode. I've always heard that it's super rare, or due to neglect/bad-repair but this guy supposedly had a tank he keeps drained blow. I've been looking for a compressor and wanted to get a well made older one. I looked at a really nice Sears twin piston up for auction that I planned on winning.... until I saw a patch on the bottom.

I keep thinking maybe what I should do is convert an expired CNG tank over for air.... those are rated for thousands of PSI, so an air compressor is never going blow one. Also, since they're a composite, they don't rust.
 

PlayingWithTBI

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You should have any air tanks you use in your shop hydrostatic tested every five years
I thought it was 10 years but, I could be wrong. Where I worked, we had them ultrasound tested so we didn't have to take them out of service. Kinda like @skylark posted, we had auto drains, and then dryers for instrument air. In one building we had 3 - 200HP screw compressors, ran 2 at a time with 1 for backup.
 

Erik the Awful

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It may be 10 years for the civilian sector, but in the Air Force we're supposed to test every 5 years. Auto drains are nice, but they don't prevent rust, they just get rid of the moisture that's condensed at the bottom. They can also fail.

...and instead of tearing my compressor down yesterday, I fixed lawnmowers and dorked around with my 500 Cadillac oil pan. I'm still trying to figure out how I'm going to pressurize it to 225 psi at home if I don't drag it to work.
 

stutaeng

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On garage journal they have threads on how to do this. I believe you fill it with water and the pressurize with one of those handheld grease guns. I've never done it though.

The idea is that if the tank fails, it would release a smaller amount of energy because fluids are non-compressible.
 

thegawd

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how does that work? I would imagine you would have to buy a cylinder full. I'm a believer in nitrogen, that's what is in my burbs tires and they do not fluctuate at all and have not lost any pressure in like 2 years or possibly even more.
 

PlayingWithTBI

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You really don't need a full bottle - they come pressurized close to 2200PSI (IIRC). We had kits we used to charge our hydraulic accumulators on the extrusion presses. It's a couple gauges, a hose, and a Schrader valve connector. For a cushion from shock we'd charge it ~80% of operating pressure so, with a working pressure of 1,500 PSI, we'd charge it @~1,200. Once the bottle got too low, we'd switch it over to use somewhere else.

For charging an air tank, one could use this and an air hose.
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www.amazon.com/BETOOLL-Nitrogen-Regulator-Equipment-Connection/dp/B01IJI04XW/ref=asc_df_B01IJI04XW?tag=bingshoppinga-20&linkCode=df0&hvadid=80676721524055&hvnetw=o&hvqmt=e&hvbmt=be&hvdev=c&hvlocint=&hvlocphy=&hvtargid=pla-4584276297919835&psc=1
 
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