# Copper for compressed air lines??



## mhagadorn (Feb 9, 2018)

Ugh, I thought I was being wise by installing a bunch of copper air lines last year.  I had PVC for about 20 years, pressurized 27/7/365, never had a problem.  Now, I have a bunch of corrosion in the copper I installed.  Is this normal?  

Corrosion has developed in my new air filter / regulator as well.  I'll try to get some pics in a followup post.


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## mhagadorn (Feb 9, 2018)

This was after I cleaned the regulator as best I could without abrasives.


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## Eddyde (Feb 9, 2018)

I built a large copper air system that was in use for about 20 years, it didn't have any corrosion issues, so I don't think its inherent to the material. I wonder if you are having some sort of electrolytic or galvanic problem, especially in such a short time. 
Yes pictures would be helpful.


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## Eddyde (Feb 9, 2018)

Crossed posts,
That looks more like it was caused by the soldering flux. Excess flux will cause some surface oxidation if left on or in the pipe, in normal water supply service it is washed away when the pipes are filled and is (should be) wiped off the outside of the joints after sweating. It doesn't get washed  away in an air system. Personally, I wouldn't worry about it, it probably won't progress much further. If you get corrosion at the threaded connections between the copper and the filter regulators, that would be a problem.


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## mhagadorn (Feb 9, 2018)

The pipe picture I posted above is after my drip loops, before the filter / regulator.  I only took that apart to investigate because my filter / regulator was corroding and filling up with garbage.  The copper after the filter regulator is also all flaky green inside. 

Maybe electrolytic, or I am now wondering if flux from soldering the copper could do to this.  I had some old school flux that I loved, but I ran out of it and threw away the container.  Maybe it was acid.  Not sure if I should try to clean the copper, or ditch it.  I really want to know what is going on.  I hate issues like this. 

Other than my compressor tank, there is no steel in my system.  When I bought the compressor, I fogged the inside of the tank with zinc primer and then Krown oil.  After a year of heavy use, the inside of the tank looks like new (painted and oiled).  

My system plumbing:  
1.  60 gallon porter cable compressor
2.  304 stainless pipe elbow & nipples
3.  1/2" brass ball valve and brass hose swivel union
4.  Air hose between the tank and the copper
5.  Brass hose barb threaded into 3/4 copper 
6.  about 20 feet of 3/4 copper (2 drip loops with brass ball valves at the bottom of each loop)
7.  3/4 copper goes in and out of the aluminum regulator / filter
8.  a few feet of 3/4 copper out of the regulator / filter (tees and ball valves)
9.  3/4" rapid air which goes to my machine shop and two garages.


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## mhagadorn (Feb 9, 2018)

LOL.  Another cross post.  Thanks.  Yep, maybe flux.  All my copper to remove water really didn't do much for me.  I have now built a refrigerated dehumidification system.  I may ditch most of the copper and thoroughly clean what I keep.  I did (always do) clean flux off the outside.  Maybe the inside will be better if I clean it too.  I can't imagine many folks clean the inside of their copper air lines.


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## Buffalo20 (Feb 9, 2018)

I spend a good deal of time and money, piping my compressed air system, in copper. About 6 months after I put it in, I had to take it out, my local residential plumbing code, does not allow the use of copper for compressed air. We were in the process of new meter water supply lines from the street and new water meters, which had to be inspected, the violation was noted then. They gave me 10 days to remove it, or fines,  but the killer was they informed the insurance company, they gave me 30 days to remove it, or total loss of homeowner’s insurance coverage. So out it came, in went black iron.


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## Tony Wells (Feb 9, 2018)

Probably true, but many people don't solder...they opt for compression or flare connections.


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## mhagadorn (Feb 9, 2018)

Buffalo20 said:


> I spend a good deal of time and money, piping my compressed air system, in copper. About 6 months after I put it in, I had to take it out, my local residential plumbing code, does not allow the use of copper for compressed air. We were in the process of meter water supply lines from the street and new water meters, which had to be inspected, the violation was noted then. They gave me 10 days to remove it, or fines,  but
> the killer was they informed the insurance company, they gave me 30 days to remove it, or total loss of homeowner’s insurance coverage. So out it came, in went black iron.



Dang, that's unfortunate.


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## mhagadorn (Feb 9, 2018)

Tony Wells said:


> Probably true, but many people don't solder...they opt for compression or flare connections.


true.  I have soft copper with flare fittings in my new air dryer setup.


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## markba633csi (Feb 9, 2018)

Looks like too much moisture in the lines- better drier needed? 
M


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## Mikelkie (Feb 9, 2018)

Are you near a factory or power station or some source or sulfurous emission to the air?
it takes very little polluted air to cause the sulfate/sulfide deposit on copper


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## Dabbler (Feb 9, 2018)

If there is electrical connection between your stainless steel and your copper, you will get a lot of galvanic corrosion. particularly if there is any trace of moisture in the lines.  If possible, separate stainless and copper with a short (1 foot) length of high pressure hose - I use hydralic, but any pvc air hose will work. 

Solved  my own corrosion problem like that using the above (about 10 years ago).

Good luck!


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## chips&more (Feb 9, 2018)

I have copper air lines. And all my connections are hard soldered. I do not have any corrosion problems. Using an acid base flux is great to get the solder to flow but has terrible long term corrosion effects. Even if you try to neutralize the acid flux it could still case corrosion later on. I do not use any kind of acid flux for that reason…Dave.


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## aliva (Feb 9, 2018)

Ive had hard 1/2 copper pipe for more than 25 years never noticed a corrosion problem or any build up of any kind. All my joints were soldered with silver solder, to meet insurance specs, I put a new line in a year ago to my mill for a power draw bar, I opted for PEX piping and shark bite fittings.
so far everything is working fine, and no corrosion. I wouldn't worry about some discoloration as longs as theres no big pieces. I would be a little concerned about an aluminum regulator, change it out to a brass unit much more compatible with moisture and more inert


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## amuller (Feb 9, 2018)

That sounds like an unusually aggressive inspection operation.  I worked in a plant that had some copper air lines and we had no problems with it.  I always put in black or galvanized steel, though.  But, I don't know of any categorical prohibition of copper in compressed air service in the usual plumbing/mechanical codes.  PVC is not allowed.  Probably CPVC also.  PEX?  I have no idea.  The main thing is proper slope, dirt pockets, drains.  For instrument air I would consider copper.


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## mhagadorn (Feb 9, 2018)

Mikelkie said:


> Are you near a factory or power station or some source or sulfurous emission to the air?
> it takes very little polluted air to cause the sulfate/sulfide deposit on copper


No factories within 10 miles. Woods and farms.


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## Eddyde (Feb 9, 2018)

At the old shop, we had run some 300' of copper for the air system, it worked well for many years. Then, when we had to bring the spray room up to code, the inspectors made us remove the copper and put in schedule 80, black "iron" pipe. The explanation was, in a fire the solder joints could separate and the jet of compressed air could intensify combustion. Luckily, they only made us redo the lines to the spray room and we were able to leave the rest of it. That's NYC for ya...


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## mhagadorn (Feb 9, 2018)

markba633csi said:


> Looks like too much moisture in the lines- better drier needed?
> M



This is in my house. The copper pipe was my “drying” system.


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## mhagadorn (Feb 9, 2018)

Going to take more apart tonight to look for more clues.


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## Silverbullet (Feb 9, 2018)

By looking at the set up there's some corrosive being sucked into the air lines , like bleach or ammonia , or stored fertilizer . Chemical fumes do lots of this type damage. The shop next to mine we installed copper forty years ago and have never had a problem , the tank for years only got emptied about once a year. Mechanics don't do much painting so a little moisture didn't bother . Plus it was a three hundred gallon tank.


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