Rust in air compressor tank... how to prevent?

[lschwarcz]

Hi Everyone,

I have an Ingersoll Rand SS5L5 60 gallon vertical air compressor in my home shop that's close to 2 years old. It's lightly used for home hobby use only so it doesn't get used daily.

Yesterday I opened the drain valve at the bottom of the tank when I was done and the air stopped when the tank was still at 20 PSI. I opened another tap and let the rest of the air out and then removed my drain and found some rust at the bottom of the tank. I don't open the drain at the bottom after every single use but I try to do it pretty often.

Fortunately it's not too bad and I can clean it up but how can I prevent this in the future?

I'm thinking I could put the bottom drain back in place and pour some Evapo-Rust in the tank to remove the existing rust. After some time sitting I could then drain it out and let the tank dry.

But what about something to prevent rust of forming again? I called IR and the insides of the tanks are not treated or coated to prevent rust. Is there some product out there that I could apply that would stop rust from forming forever? The only access to the inside are threaded holes at the top and bottom that are only a couple of inches across. I could pour some fluid in the top, let it sit and then drain. I don't think I need the whole inside treated. Just the bottom few inches I think would be enough.

Any suggestions on what I could try?

Thanks!
Larry.

 

[The Cobbler]

a good regime of regularly draining tank is your best option.

 

[lschwarcz]

a good regime of regularly draining tank is your best option.

Agreed. But in this case I do regularly drain the tank... I guess just not often enough! I think I'll start opening the bottom drain after each use.

I just got off the phone with POR-15. The guy there said that I could use their cleaner, then metal prep and then the fuel tank sealer to permanently seal the bottom of the tank from moisture so it won't rust. Not the cheapest solution but if it works it'll be worth it!

Thanks,
Larry.

 

[no704]

Get an auto drain.

 

[Jswain]

You're making a mountain out of a mole hill. Drain the moisture everytime you use it and worry about something else. Don't need to completely drain down the tank. If you've been using it a lot, drain the moisture when you're done and go back out the next day and drain it again once the tank is cooled down.

 

[tarmy]

I have posted these pics before. This was a Speedaire tank about 20 years old that got a pin hole leak. I replaced it and cut the old tank open out of curiosity. This tank was usually (not always) drained every time it was used. Rust is part of the process.

 

[Shoreline_]

If you want something to last forever you're going to pay out the nose. Air receivers now are only rated to last so long as a "wet tank" or basically a long term consumable.

You options are to replace it with a stainless steel tank or a internally coated tank.

Also that speedaire tank probably isn't even asme coded haha. Look how thin that is. The best Chinesium. Something from Machester Tank or Samuel Pressure Vessel would last so much longer.

 

[whateg01]

...

You options are to replace it with a stainless steel tank or a internally coated tank.

...

I think that's what op is after. I have thought about coating the inside of my compressor tank with something like por15, or maybe just a good epoxy paint, at least the bottom of the tank anyway.

 

[Shoreline_]

I think that's what op is after. I have thought about coating the inside of my compressor tank with something like por15, or maybe just a good epoxy paint, at least the bottom of the tank anyway.

You gotta do it when it's new. Your pump will naturally pass oil into the tank and with time and unless you fill the thing with acetone- i don't know how you're gonna get it clean enough.

 

[tarmy]

If you want something to last forever you're going to pay out the nose. Air receivers now are only rated to last so long as a "wet tank" or basically a long term consumable.

You options are to replace it with a stainless steel tank or a internally coated tank.

Also that speedaire tank probably isn't even asme coded haha. Look how thin that is. The best Chinesium. Something from Machester Tank or Samuel Pressure Vessel would last so much longer.

It is the old style that is way better than today’s tanks. Maybe take another look at the wall thickness up by my hand in one pick. Most consumer brands these days are **** tanks.

 

[VolvoRyan]

On my consumer grade compressors, I run a 90 out the bottom, some straight pipe, a ball valve, and then some tubing out under the overhead door. I drain the tanks after every use, and leave the valve open until the next time I need the compressor.

I'm one of those guys who loves air tools, but has conceded that cordless tools are capable and convenient. Even the M12 stuff has displaced a lot of air tool use. Compressors don't get used anywhere near as much these days.

My approach is probably even less efficient on your 60g than my 30's.

-Ryan

 

[Vinny]

Separate the tank and dump so phosphoric acid inside. Make sure to move the tank so it's coated well (roll it around in the backyard). Then, take your preferred rust proof paint (I like Masteseries), thin it to be more watery, then pour it in and again move the tank all around. That will make it rust proof. Used to do this on large semi truck gas tanks.
If you can weld, then you can cut a hole in it and sand the he'll out of it, weld it up, and do the same.

 

[The Cobbler]

That will make it rust proof

maybe rust resistant, but not rust proof.

If you can weld, then you can cut a hole in it and sand the he'll out of it, weld it up, and do the same.

bad advice unless qualified for welding pressure vessels

 

[imagineer]

For what it's worth . . .

I bought a used Husky 60 gallon vertical compressor that was used in a cabinet shop. The compressor didn't have an intake filter and I suspected that fine saw dust had built up inside the tank. I disassembled it and removed the bottom drain and sure enough, there was a lot of wet, rusty saw dust.

I used a garden hose and flushed the tank out with water until it ran clear(ish). With the tank vertical I set up a heat gun on low, blowing into the outlet port, and allowed the air to escape out the bottom drain. After about 4 hours, I reinstalled the drain, poured in a quart of WD-40, plugged the 2 ports then rolled the tank around the yard for a bit to ensure the entire inside was coated with WD-40.

Back vertical, I removed the drain again and allowed the bulk of the WD-40 to drip out, then put the whole thing back together.

This was about 20 years ago and now, when I drain the tank, very little rust is evident.

 

[JradM]

What about JUST using metal prep - skip all the other steps?

Also, don't drain your tank all the way - just blow out the condensation and then stop. The drain is at the bottom, so it should blow out moisture first, then air. Otherwise you're just pumping in yet more moist air next time you refill the tank.

My thinking is that metal prep by itself seems to prevent rust. It's supposed to leave a zinc phosphate coating behind.

Where's that fellow who talks about using metal prep as a rust-preventing finish all the time? He probably knows more about it than I do.

 

[BrandonV]

I wouldn't worry about it. You should probably be buying a new tank before rust becomes a serious issue.

 

[whateg01]

Nobody's mentioned fluid film? I thought that was the be all end all for rust prevention? (I know you don't intentionally put oily stuff in the compressor tank, but I'm still surprised it's not mentioned)

 

[Davefr]

Instead of using the valve on the bottom of the tank, I added a fitting and a few feet of hose with the ball valve at the end of the hose.

The hose will fill up with water first before any accumulates in the tank, In addition the valve at the end of the hose is a hell of a lot easier to access and drain then the valve mounted to the underside of the tank.

 

[isb cornbinder]

I went to a business closing sale. I bought enough stuff to fill the box of my truck. One of the items is a titanium high pressure tank. The tank is wrapped in fiber and resin and is certified to 4000 PSI. I doubt this tank is going to rust. I have owned the tank for 20 years. It is hiding under a workbench.

 

[cgrutt]

I need to buy a new tank for an old compressor and have been thinking about this. One concern I'd have with any sort of paint is having it cure properly being basically in an enclosed container. I would think a two part epoxy might be best as it has a catalyst added for curing. Wouldn't think you would want anything oily or bulky such as fluid film because whatever you put in tank is likely to find it's way in your air tools or worse, paint, if that's what you use compressor for. I watched a video where someone sprayed gt85 (a Teflon based metal protector and water displacer) inside a tank with a long hose and rod similar to old undercoating tools. Have no idea how that worked out. Thinking maybe some sort of air dryer on intake would help. Best to drain daily no matter what.

 

[mikedodge]

The problem with painting or coating it is there's no way to properly clean the inside of the tank first so with the moisture, rust and any oily blowby from the compressor already in there its not going to seal properly and end up making it worse. Then you'll end end with bigger rust scale or loose paint causing more problems.