Galvanized Pipe for plumbing air lines ...

by Tony
(Fayetteville, NC)

How does galvanized pipe rank for compressed air plumbing?

I am currently using PVC (I know I know, not recommended) and I want to upgrade, however I do not want the cost of copper nor do I have the skills needed anyway, and black pipe rusts like crazy.

Bill answers...

Hi Tony, nice hearing from you.

First off, PVC isn't just "not recommended", it could be catastrophic. PVC's burst threshold lowers the hotter it gets, and I believe that Fayetteville NC might get the odd warmish day?

When PVC lets go, it often shatters, and anyone and anything around could get shredded.

If I had lots of money, my first choice for a compressed air supply line would be copper. But you're right, it has become very expensive, and even though there are other alternatives to 'sweating' the copper, that would be my first choice for putting copper lines and fittings together.

You know, I don't know of anyone that's using galvanized pipe as a compressed air line. Don't know why. As long as the pipe has the pressure rating (and it should), then the galvanized coating would stop rust inside the lines, making it, in my opinion, a good choice.

By the way, I'd much rather 'sweat' copper than thread pipe.

Anyone else have any ideas for Tony and the use of galvanized pipe for an air supply.

Good luck.


Update: Please see comments regarding other people's take on using galvanized pipe for plumbing compressed air.

Tony, I'm new to this whole compressor world, but in doing some reading I came across this quote on the TP Tools website. "We do not recommend galvanized metal pipe, as galvanization can come off the inside of the pipe, clogging separators and regulators."

Matt...thanks very much for your input! I guess the "toss up" is do you get better quality air from galvanized, with the risk of galvanization coming off inside the pipe, or from black pipe knowing that rust will develop for sure, and that rust will flow down the line to your application.

Regardless of your choice of pipe, you really need to have a filter / separator before each application that uses compressed air. These take out the free water, and will remove the "bricks and mortar" that flows down the air lines before it gets to your application.

Again, thank you very much for "chiming in". I have never professed to know it all...maybe it just sounds that way sometimes. ;-) I appreciate any input from folks that have done more reading or have more experience than me.


Comment from Paul Pearce:
I judge galvanized piping as a totally wrong application that is doomed to failure.

I can't imagine how and why anyone would apply this type of weak and inherently flawed piping. It is weak because it is totally susceptible to corrosion, flaking, and pin-hole defects - depending on the skill with which it is dipped.

And once a pin-hole (or even smaller holes) has been established, the corrosion starts immediately.

There is no way on this earth that anyone can guarantee that there is no defect or flaw in a given galvanization - hot-dipped or not hot-dipped.

And then there is the real hard issue of how does one inspect the surface that is really supposed to be doing the "protecting": the internal pipe surface!

To date I've never heard or read of anyone daring to state that the internal surface of a galvanized pipe can be safely guaranteed not to have defects or flaws - because it can't be inspected.

nd that's not all.

Most, if not all galvanized pipe is threaded. The moment it is threaded, the galvanization has been compromised and breeched. There is no longer any "protection", since the galvanization has been stripped and removed at the weakest point - the threads! This methodology or system of ensuring corrosion protection for a pipe has all the ingredients for its own demise.

Bill responds...

Hey Paul, how do you really feel about using galvanized pipe for compressed air? :-)

Just kidding.

Thank you for your in depth comment.


Paul Pearce
1-705-789-3313 ext 292
Algonquin Automotive
1 Crescent Road
Huntsville Ontario
Comment from David:
Your right the bottom line is in air qualitiy. If you just using the the air to blow off and clean machinery the galvinized is a perfectly good solution not to mention cost effective.

Look at it this way, galvinized pipe was used in home plumbing for years, downside was rust in the lines. but leaks came way later down the road 10 maybe 15, 20 years. if your just moving air and quality does not matter then by all means use galvinized. If its inatalled properly then you should get many years of use out of it before there is a problem.

Also keep in mind the enviorment it is installed in. Outside or inside. If your coming from outside to inside then maybe use copper until you enter the inside. Copper has the same corrosin problems that galvinized has when exposed to moisture it oxidizes and pinholes develope.

I know places completly piped in galvinized pipe with no problems because it is used for just cleaning off equipment. If your using air for pnuematic cylinders and other related applications then yes copper is the best alternative.
An anonymous contributor for galvanized pipe in plumbing air:
I have my metal fab shop piped with nothing but galvanized. It has been in place for close to 20 years, without any issues at all. We use many different machines, and a vast array of hand tools. My compressor is located in an unheated environment, and the main line then enters the heated workspace. This would certainly seem to increase moisture issues, but to date,it has not been a problem. When I do find minor excess moisture in the system, it's usually my failure to drain the dryer. Having said that, I would most likely use copper next time, it's just easier. Save the plastic for moving poo, hopefully downhill.
Galvanized pipe not as good as it once was?
Galvanized pipes are not that bad. The thing is that galvanised pipes are not as good as they were in the past...

In my backyard I have lots of galvanised pipes produced in 1970's and 1980's
And guess what ? there is almost no rust (keep in mind they're exposed to rain)

I do have some newer pipes too but I don't keep them outside... becasue they rust almost instantly when exposed to moisture, rain etc.

stuff just isn't as good as it was in the past...
Anonymous says no to galvanized pipe:
galvanized pipe flakes off on the inside that is why they dont use it.
An aluminum option to using galvanized pipe in air systesm:
Try Transair - Aluminum Compressed air pipe system. The alloy will not corrode, plus guaranteed leak free. This system was specifically designed for the distribution of compressed air, inert gases and vacuum.
And one more saying galvanized is bad:
I have worked as an industrial millwright/mechanic for the past 15 years - 6 of them as a fluid power specialist. I would not recommend using galvanized pipe for any compressed air applications! Regardless of the use of dryers and/or lubricators, there are small flakes of the coating that will flake off of the inside of the pipe. This will cause failures in valving, actuators & air tools.

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What about galvanized pipe?

by egor
(Orlando, FL, USA)

The plumbing section mentions black pipe, what about galvanized pipe?

Hi Egor...

I've reviewed galvanized pipe for compressed air plumbing a few times. In one sense, it makes good sense, since the galvanized pipe doesn't rust.

On the other hand, some folks think that the galvanization on the inside isn't secure, and that particulates can dislodge and wander down your air lines to clog your filters, or worse, if you don't have an in-line filter, to mess up your tools.

Tell you what. I'm going to find a galvanized manufacturer and get the straight goods from them. Tune in for that one soon.

The other question I would have is cost. I haven't compared pricing on galvanized pipe to other black pip, so can't comment with certainty, except that it will be more expensive.

Like black pipe, galvanized is normally installed by threading the pipe with a thread die and then screwing the components together. For some folks, that process is prohibitive too.

Anyone else have any experience with galvanized pipe for air lines?



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