using galvanized pipe for air lines

[housewolf]

Normal plumbing solder is fine. Unless something has recently changed. I have 3/4" copper tube, 155 PSI, lead free plumbing solder, and it's been trouble free for 20 years.

No doubt. I’ve regularly tested copper water pipe with air up to 175 psi without a problem.

 

[BTL-A4]

I got a 50' poly airline at HD for $20. I moved the compressor to a more convenient location. When I need a longer hose, I'll hook up the 50' line. Done.

As I thought about it, I don't really use air all over the garage, and when I do, I use my bigger compressor with the air hose on a reel. It was going to be a lot of cost and work for little return for me to run lines all over.

Thanks for all the advice and comments, I found them helpful and informative for if I do decide to add airlines.

 

[nadogail]

The air lines in my small Workshop are Air Hoses threaded through the open ceiling joists.

 

[Squez]

I would like to run an air line from my small compressor to a connector closer to where I use the air hose. The run would be about 15 feet. Can I use galvanized pipe for this? I can use copper, but it's pricey and I've never worked with it. I've heard PVC is a no no. That leaves galvanized. The pressure would be about 150 or so. The compressor is shut off between uses. I might even put a bleed valve on the line so there's no pressure in it except when it's used. I'm thinking a small diameter, like 1/2" would work. Do they even make a smaller diameter? This is used for blowing air off/out of tools, projects, etc., so I don't need massive airflow. Thoughts and comments from those who know would be much appreciated. Thanks!

Pvc is a no no ? I guess I never got that memo.. I’ve had pvc air lines running through my garage for 8 years without issue.

 

[nadogail]

The use of PVC pipe for compressed air has been a "Hot Button" issue on this forum for years. PVC pipe when used for compressed air has been known to occasionally fail spectacularly..

 

[Stuart in MN]

PVC is a hot button many places. There are probably at least a zillion discussions here about it that you can find with a search.

The short answer is PVC is not ductile, like copper or steel - when it's damaged it breaks into pieces, unlike metal that bends. If a PVC pipe is damaged or breaks when it's full of water, the worst that happens is the water squirts out. If it's damaged when it's full of compressed air, the rapidly expanding air will blow broken bits of PVC all over, like shrapnel.

The pressure rating for PVC is for use with noncompressible liquids, not compressible gases, and if you look at the manufacturer's specifications they'll specifically warn against its use for gases.

I've personally seen PVC fail, and yes there were sharp bits of plastic stuck in the walls. Many people have used it without issues, but they've been lucky. It's essentially a bomb waiting to go off.

 

[TuckerSailor]

I got the memo. I had 1/2 inch pvc for around 10 years and replaced it with black iron 1/2 inch. It scared me how brittle the pvc was when I took it down. Disaster avoided. Back to the question at hand, black iron is cheap and available everywhere with possible rusting inside, galvanized may be more expensive with flaking inside . I would not be afraid of either.

 

[sgdawson]

This discussion of copper air lines reminded me of the setup at Circuit of the Americas, the F1 track in Austin. Budget was probably not an issue for this installation.

Interesting there is no provision for drains on the individual drops. Maybe air is dried at the compressor? Main trunk is also larger than the branches, so any condensate can run along trunk below the branch connections.

Are the angled connectors and T-connections crimped on? I don't see solder and they have an unfamiliar rib running around the circumference.

 

[RaisedByWolves]

Black iron pipe will let rust particles loose in your air. I've disassembled old systems and was amazed how much rust there was. You need a filter at each point of use.
Easy home solution is 1/2" type M copper water pipe with sweat fittings.

I work in a doctors built in the late 30s and we still have some of the original sch80 runs in use.

The 4” trunk lines are all original and many of the drops are also. The “Lost technology” of running airlines like this is to have a larger termination “sump” where the air is terminated and this is fitted with a drain.

The increase in pipe diameter slows the air down and particulates and water drop out into the sump and can be drained off.

When we used to do out yearly shutdown they would evacuate whoever was working after removing all Olof the drains and blow down the system leg by leg to remove rust, scale and water.

This was jet engine loud and often made a mess, but our system was clean for nearly 80yrs of use.

Now that many of the assembly guns are electric this is rarely done plant wide, but the old guys still blow down their shops to keep their air clean.