How do I tell if compessor tank is safe?

[MushCreek]

How old a compressor would you feel safe around? I was looking at my cheap old Black Max 60 gallon, and realized it is 23 years old! I 'usually' drain it every day, but can't say with certainty that I always have. In FL, a surprising amount of water comes out after a day of use.

So at what point do you ditch it for a new one? I know that repair shops won't touch a compressor past a certain age, but don't know what that age is. My compressor is only 125 PSI, but still wouldn't want it blowing up next to me. Thoughts?

 

[bmwpowere36m3]

Besides visual, maybe a UT for thickness... similar to checks on old oil tanks (for insurance purposes). Its only 125 psi, but I agree I wouldn't want it blowing next to me.

Probably boils down to what you feel comfortable with.

 

[gdocktor3]

My compressor has a large 1-1/4" plug in the end that I removed a few months ago. Took a look inside and it was in good shape. A visual inspection of the inside might be a good idea if possible on yours.

 

[PSYKO_Inc]

Hydro test it. Cap off all the ports (including removing the check valve and plugging the port) and fill the tank as full as possible with water. Then pressurize the remaining air in the tank with either a grease gun or high pressure gas cylinder (argon, c25, nitrogen, hpa, whatever you have available. Not oxygen ) and regulator. Run it to 150% of the max working pressure stamped on the tank. If it breaks, you get wet but it won't hurt you, and it was scrap anyway. If it holds, you're good. I recently picked up a tank built in 1946 that I'll be testing soon, 3/16 wall thickness so I don't think there will be any problems.

 

[Zeke]

I haven't done this (disclaimer) but interweb knowledge says to empty the tank of air and any water and then gently tap on the bottom with a hammer. If it sounds different than the top, beware. Weld lines seem to be a point of failure just so you know. Any pin hole leaks that can be seen with a soapy liquid flooded on the tank surface is cause for immediate disposal.

 

[Arkansas COB]

I have had a few tanks go bad over the years. Everytime they always developed a big pin hole first and the air hissing let me know they was done for. Never had one just blow up because the tank went bad. I will say i never leave mine running when im not in the barn using it.

 

[gungatim]

I ditch the tank when it starts leaking. you could always have it hydro tested, but for me, a leak is good enough for me. only ever had one take go bad, the old standby CH 2hp 20 gal. lasted from '85 to '08, drained it maybe a half dozen times over the years. rust got it at the weld bung for the drain. My new compressor has an auto drain. Lesson learned.

 

[MushCreek]

My little Emglo nail gun compressor has had a pinhole for the 5 years I've been using it! I guess I'll retire it or get a new tank. The big compressor has a big bung I could try to take out for a visual.

 

[Ole Slewfoot]

Mine says '1948' on it, but I like living on the edge.

 

[sberry]

Mine has been on since 72 and had at least a couple gallons in it a couple times.

 

[Fixin'Stuff]

Security video of a small compressor tank exploding:

Scary stuff!

Where can one get a tank hydro tested? When I search the yellow pages for "hydro testing" I get a list of nearly 400 plumbers. Would a welding supply know where to get it done? I know that welding tanks have to be tested from time to time. Or perhaps a propane supplier? Most people won't bother testing a tank for their grill, as it doesn't cost much more to just get a new tank. But air compressor tanks aren't cheap.

 

[stonesfan68]

Do a search for ASME pressure vessels or pressure vessel fabrication. They may not want to mess with a little tank, but you never know.

You can also plug up all of the vessel's nozzles and then use a pressure washer (with adapters and a pressure gauge) to fill the tank to 150% of the rated tank pressure. If the tank leaks then it needs to be replaced.

 

[Know Wosad]

Get a $15 China usb scope off ebay and go in for a look.

 

[Handyfarmer]

Hydro test it, or have it hydro tested,

 

[slip knot]

I'm always skeptical of these tank explosion risks due to old tanks. I've had a few leak over the years and seen others with holes in them but I've never personally knew of anyone having a tank explode.

I'm more concerned with the hacks that people do to override the safeties in the compressors. I've seen multiple times where the safety popoff was wired closed or was completely gone. I've also seen where people take the factory switch off and replace it with a higher cut out. I can see where these could certainly cause catastrophic tank failure. I wonder on the few explosions that we hear about if this wasn't a bigger contributing factor than an old tank.

 

[danski0224]

Cut a hole in it with an angle grinder, something big enough to see into, like 10" x 10" or bigger.

If it looks good, weld the piece back in.....




The compressor in that video looked pretty rough. Plenty of visible rust on the outside. The flange on the end bells looked clean, like there was no weld penetration. While the video is scary and thought provoking, there is no way to know if the (1) pressure switch was working properly (or if it has been bypassed) or (2) if the pressure relief valve was working (or has been tampered with).

I would tend to think that such a catastrophic failure like the one shown in the video is extremely unlikely without additional "modifications" to the safety systems, or a hidden manufacturing defect.

If you are following the manufacturer guidelines for maintenance and checking the safety equipment as instructed, the tank is most likely safe to use. I am not aware of any required re-certifications for homeowner grade or other small air compressor tanks. Without doing any research myself, it is likely that re-certifications become required above a certain pressure class and/or volume.

 

[lakeroadster]

Age has no bearing on air tank usable life. Never ever weld on an ASME stamped pressure vessel... unless you are a certified welder working for an ASME certified shop.

Need to find a legit shop code shop to do the hydrotest or repairs? Go to this link, type in city and state.. happy hunting: http://www.nationalboard.org/ManufacturerDirectory.aspx

Want to hydrotest the tank yourself... Perform a visual internal inspection and then hydrotest the tank at its stamped rated pressure... not at 1.5 x the pressure. Ensuring all the air is out of the tank is of critical importance.