Old, rusty compressor tank repair
 

I have a rusty compressor tank (30 gallon) that still holds air, but the bottom inside looks pretty weathered.

I was thinking of cleaning as best as I can and using some kind of tank sealant to protect the inside. Like POR or something recommended for fuel tanks.

A very important reason for doing this would be to 'raise' the profile around the water drain so that water can get out.


Is this futile?

It's worse than futile. You know for a fact that the steel is compromised inside, but you don't know how strong it is.

Throw it away. It could kill someone.

really?

I did not know they broke violently... I was under the impression failure would begin as chronic leaking.

is it really done for? I can smack it around with a hammer and it sounds / feels kinda solid

get new one...it could violently rupture, although it will most likely just quit holding air. better safe than sorry

not what I wanted to hear

thank you.

Yes, usually they will fail by leaking, but I have seen the aftermath of an explosion. Fortunately, nobody was near the thing when it went, but it put a huge dent in the steel wall of the building.

yeah... I really don't need that.

how big was it?

a 30 gallon tank could potentially send shrapnel through a wall, if over pressured

The old cast iron ones would explode,,, the new steel ones just rip apart.

that makes more sense. How can I tell the difference? There are welds where the elliptical section meets the cylindrical mdisection.

If you can pick it up it's not cast iron. Get rid of it, it's junk.

It's been quite a few years, but I recall that it was fairly large. Probably about 40 gallon. It was pretty old at the time.

I try to keep mine drained, and installed a ball valve in place of the really horrible screw valve that was installed. It has a hose leading to a catch container, making draining the tank a ten-second job. I'll do it before and after a job where I'm using the compressor.

All this reminds me, I'm behind schedule on my compressor oil change.

Hydrostatic test it to 300 lbs is safe and effective. Being filled with water there is no explosion possible as liquids do not change volume for all practical purposes. In theory you could sit on top of it during the test I imagine.
I would not but you are safe six inches away or less even during the test.

Most my compressor tanks will have some internal corrosion. I never test them as they are in a contained remote area. The ones that are physically close to me when working are fairly new. If I did distrust them I would just fill them with water and take the pressure up to 300 to 350 lbs pressure depending on what the individual compressor was shutting off at.

Your problem is to rig a hydralic pump to raise the pressure and a gauge to read it. Depending on the price of a replacement tank it may or may not be worth the effort.

that is brilliant, Barry.

how about filling it 'mostly' with water then using less than 10% air on top.. this thing sits horizontally. I can still utilize the gauges and pump that I have by doing this.

It is one of those older style compressors with a very heavy duty pump.

Tank says 150 psi working pressure.


Perhaps a radiator shop might test it??

Do not chance it. You can get a replacement tank for less than 1/3 of the price of a new compressor, or find a good used tank with a bad pump for next to nothing on CL. I have seen tanks go both ways, one was a gas-powered unit at a rental shop (horrible nightmare place that should have been shut down long before I got there) that just leaked and then popped the valve out the bottom. The other was a converted water heater tank in the attic of a friend's shop. He had three 80gallon tanks in a row, one of the end ones blew violently and took out the middle one. There was no roof left on the shop.