Endoscope revealed a rusty tank

[swampfire]

This is my first post, so hello! I hope I’m posting this in the right sub-forum.

I’ve had my 30-gallon Industrial Air compressor for 8 years, but only recently learned how important it is to drain it. I found a great endoscope with a side camera for just $70, so decided to try it. I had no problem getting it in the 1/4” NPT drain hole, and the side camera showed lots of yellow surface rust, but also some angry-looking red rust. This is all in the bottom 1”, and the rest of the tank looks pristine.

Still, I know that it’s too dangerous to use at this point. I’m trying to find a reasonably-priced replacement tank. I found a 20-gallon receiver tank (“Airhoss”), made the US by Industrial Air (I’m too new to post a link).

Is it possible to take the pump off of my old A.C., mount it on a shelf, and then run it as an input to this receiver tank? If you’ve done this, I’d love to hear from you.

 

[Bert_]

Unless there is heavy pitting I wouldn't change anything.

 

[Blickus]

Impossible to quantify the metal loss from a 2D fiber-optic scope. Unless you see deep localized pits, or obvious loss adjacent to the welds, it is most likely generalized surface rust. Even heavy scaling is difficult to quantify. Approx 4:1 ratio of rust scale thickness to steel loss, if the scale is intact. Only an ultrasonic thickness survey can determine whether the remaining thickness.

If you’re questioning the safety of the vessel, hydrotest it (self) or have it inspected.

Retired API 570, National Board, State of PA engineer/inspector

 

[swampfire]

I like the idea of DIY hydrostatic testing. It would be a lot cheaper/smarter to buy a pressure washer and test this once a year. I can’t help thinking that if explosions weren’t so rare, we’d hear a lot more about them. I can’t be the only fool to forget to drain his air compressor.

 

[nadogail]

Draining your air tank IMHO is probably the most important thing I do to extend the life of my compresser.

I received it new with an inconveniently located drain **** in the bottom of the vertical tank, I came to the conclusion that the manufacturer used the cheapest valve that would meet the requirement to have a tank drain.

My solution was to remove the valve; replace it with a street ell and ****** over to a ball valve that I can operate with my toe.

 

[swampfire]

Draining your air tank IMHO is probably the most important thing I do to extend the life of my compresser.

I received it new with an inconveniently located drain **** in the bottom of the vertical tank, I came to the conclusion that the manufacturer used the cheapest valve that would meet the requirement to have a tank drain.

My solution was to remove the valve; replace it with a street ell and ****** over to a ball valve that I can operate with my toe.

That’s exactly what I was in the process of doing. It’s ridiculous that you have to get on the floor to use the petcock that comes with it. It’s a great modification.

 

[swampfire]

Just a few more posts, and I’ll be able to share the video.

Any thoughts on using Evaporust inside the tank to convert the rust?

 

[swampfire]

I also found a few videos where they used a grease gun to pump water into the tank for pressure-testing. I may try that.

 

[swampfire]

Okay, here’s my video. Sorry for the bad editing.

 

[Busted Knucles]

Put some sand or small rocks in it and rotate it and clean up the area and take another look. What is the largest fitting on the tank.

 

[swampfire]

Put some sand or small rocks in it and rotate it and clean up the area and take another look. What is the largest fitting on the tank.

The bottom bushing is 1.5” NPSM. I’ll see if I can get that off, which would give me pretty good access to the rust.

 

[quickfarms]

This is how I got mine out



I drilled a bunch of 1/4” holes in the plug as close together as possible and used a chisel to take out the center and the rest of the plug

 

[swampfire]

I’m surprised, the bung came right off of mine just now with a pair of channel locks. Now I can get in there with a wire brush and get the loose stuff off. I also ordered a grease gun for hydrostatic testing. I may not worry about removing all the rust, it seems inevitable anyway.

 

[CraigStu]

My 35 yr old Craftsman gets drained every couple of years. So far all is well. I saw an explosion post on a car forum a year or so ago and thought maybe I should buy a new tank. Looked at them and found they were in the $300 area and figured I'd be better off buying a new compressor. Looked a them but found my old one is 7.7cfm at 90# and it's hard to duplicate that for <$700. So I stalled on that project. I still don't understand how a rust hole could cause an explosion. Seems to me it would just cause a leak.

 

[jmarkwolf]

There is an interesting Youtube video by Keith Rucker of Vintage Machinery showing how he did a pressure test on a vertical compressor tank with a pressure washer.

 

[HaiKarate]

Just use the GD thing and drain it from here on out.

 

[santagary]

Looks like endoscopy I had a few years ago...doc said I was all clear and not to worry!

 

[swampfire]

I’d be all over this 20-gallon tank, if it had a drain for the vertical position:

https://www.amazon.com/dp/B01N1F1YF0/?tag=atomicindus08-20

 

[BillK]

If it is only 8 years old personally I think you are worrying about nothing. My compressor here at the shop is 35 years old and might get drained once a week or so ? I dont plan on doing anything to it other than using it.

Just curious . . . has anyone here actually had first hand knowledge of a tank exploding ? I dont mean what you see on U-tube and on the internet. Have you actually had one or maybe a friend have one come apart ? I am 70 years old and have been around cars and shops my entire life. I do machine work for shops in a 40 mile radius. I certainly have never heard of one exploding.

Not saying it cant happen, just think it is a way overblown issue.

 

[Lassen Forge]

Impossible to quantify the metal loss from a 2D fiber-optic scope. Unless you see deep localized pits, or obvious loss adjacent to the welds, it is most likely generalized surface rust. Even heavy scaling is difficult to quantify. Approx 4:1 ratio of rust scale thickness to steel loss, if the scale is intact. Only an ultrasonic thickness survey can determine whether the remaining thickness.

If you’re questioning the safety of the vessel, hydrotest it (self) or have it inspected.

Retired API 570, National Board, State of PA engineer/inspector

Nailed it.

 

[swampfire]

@BillK and others, I think you’re right. I’m just going to do a DIY hydro test on it to satisfy myself, then I’ll just use it. And I agree that while there are definitely anecdotes of exploding compressors, it must only happen to an unlucky few. I couldn’t even find any info on accident statistics; they seem to be more worried you’ll blow your eye out of its socket.

 

[SALIV8]

I dont recommend doing this but I used a leaking air compressor tank for several years. There was a small rust hole in the bottom and I liked that is was now a self draining tank. all the moisture came out of the hole each time i used it. Lol.

I had it attached to the concrete floor with wedge anchors and always thought it would just get worse and worse. It never got worse and I ended up swapping it out for a much much newer 15 year old compressor tank that was never drained.

 

[swampfire]

I’m stilll planning to test and use my tank, but this is an interesting option I just found:

https://www.summitracing.com/parts/fip-9277

The first review says he used it to replace the tank on his air compressor.

 

[brownbagg]

99% of the time, they just going get a pin hole and go pffffffffffff forever
I had one get a pin hole twenty years ago, I just welded some scrap over it, and kept going

 

[supermage87]

That’s exactly what I was in the process of doing. It’s ridiculous that you have to get on the floor to use the petcock that comes with it. It’s a great modification.

Yeah. You have to get on your knee and receive a full load of ...rusty water on your face when it bounce off the floor

Envoyé de mon SM-G986W en utilisant Tapatalk

 

[Kobuck]

Add fluid film to the tank!

 

[bigdav160]

99% of the time, they just going get a pin hole and go pffffffffffff forever
I had one get a pin hole twenty years ago, I just welded some scrap over it, and kept going

Exactly. "Exploding" with 100 psi? I don't think so.

 

[LS6 Tommy]

Eat more fiber...

Tommy