Evaluating used air tanks

[Keith S]

I am going to look at a used 60 gallon air compressor tank tomorrow and I'm curious what red flags I should be looking for. This is just a bare tank, no compressor. The current owner says that it has no rust on the outside and he just had it pumped up to 130 psi and it held for several days. What else should I look for and what should make me run away as fast as possible?

Thank you
Keith

 

[DekeT]

Why didn't the tank hold air indefinitely instead of just days?

 

[sublimate]

what should make me run away as fast as possible?

If it's used.

 

[Keith S]

Why didn't the tank hold air indefinitely instead of just days?

He only had it pumped up that long. he said it held the pressure the entire time.

 

[Cyberbear]

If the tank has inspection ports, open them and look inside for signs of rust. Ask why the tank was stripped down and is no longer an a/c and is offered for sale. What is the date of the tank? Horizontal or vertical?
Tap the bottom of the tank with a small ball peen hammer and feel and listen for thin spots. Buying an unknown used tank comes with many pit falls, buyer beware.

 

[dkroth]

If you can, roll the tank around on the ground and listen for rust scale flopping around on the inside.

Do you have a small camera or cell phone camera? Open the inspection ports and snap a pic of the inside bottom of the tank.

Tap the bottom of the tank with a hammer. It should "ring". If it has a dead sound it could be well-rusted inside.

If you do buy the tank consider pressure testing it yourself. There are posts here that describe how. Basically you fill the tank with water, add a pressure gauge and then run the pressure up to something that's much more than it'll ever see in production. You can use a grease gun with zerk fitting to accomplish this. Remember, you're starting with a tank that's full of water so it doesn't take too many pumps to build pressure. Let the tank sit for a day to see if it leaks.

Good luck and let us know what happens.