What is the best pipe material for air compressor lines?

There are some types of air pipe should you consider for your air compressor, and others you shouldn’t. If I had lots of money, my first choice for a compressed air supply pipeline would be copper. But 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.

Odds are good that a new, lower-cost, DIY-type air compressor will come with a low-cost PVC hose. That hose will have a connector on one end, and a couple on the other.

The PVC hose that came as part of one of my compressors was very hard to work with. The connector leaked around the barb when it was plugged into the compressor coupler. When the weather got cool I could not unroll it easily. It would not lay flat on the floor and I kept tripping over it. So I got rid of it the cheap PVC hose, and paid a bit more to acquire much easier-to-use rubber hose, one with male fittings on either end. I could then add the coupler and connector of choice, which I did, using better fittings than had come with the original PVC hose.

What air pipe? - Air Hose
Rubber or rubber – vinyl air hose

If you are plumbing up a plant with air mains and drop lines and such, what type of air pipe should you consider then?

Table of Contents

Types of compressed air pipe materials

Industrial compressed air plumbing was, and continues to be built using black metal pipe. Many folks still use it as it is relatively cheap when lots of pipe is needed for a plant installation. And I suppose it is cheaper if a larger air main is needed.

List of compressed piping material types:

  • Aluminium Pipe
  • Black Pipe
  • Polyethylene Tube
  • Copper Pipe
  • Rubber Hose
  • Galvanized Pipe

Aluminum Compressed Air Piping

Aluminium being lightweight, corrosion resistant and more easily manipulated than most compressed air piping material alternatives makes it a leading choice in compressed air systems.

Aluminum is able to provide cleaner air than alternatives like black iron compressed air pipe.

Aluminium compressed air piping systems are highly modular and can be installed with ease – using standard fittings, rigid aluminium pip can be plumed around an entire facility without a single bend.

Prevost are a large player in the european market for alumium compressed air piping systems and this video really demonstrates the flexibility, yet permanence that can be achieved with these systems. That’s whether in an industrial setting, or in the at home garage!

Black Pipe Compressed Air Pipeline

Whether at home or in the plant, I personally would not select black pipe unless I absolutely had to. Despite the best efforts at drying the compressed air, some moisture will still condense in those pipes, and rusting will occur. In time, the rust scales will migrate to the air equipment and, along with the compressor oil, and air borne dust, more compressor-generated water foul up tools, valves and cylinders.

What air pipe? Black pipe?
Lengths of black pipe

I might have to use black pipe if my air mains were going to exceed 2″ in diameter. There are not too many other options in piping once you get that big.

Polyethylene Compressed Air Tube For Air Piping Sytems

For my home shop or for a small plant, I would first consider using polyethylene tube to plumb all the airlines.

Polyethylene tube is low cost, it is rated for industrial compressed air pressures, it is very easy to install, does not react with moisture in the compressed air and it has scads of different air fittings to enable easy plumbing. Not to mention that you can buy it, rated for industrial pressures of about 300 PSI, almost anywhere plumbing goods are sold.

The problems with polyethylene tube are that if you need large volumes of air, you cannot get a tube large enough for high air flow, if you bend it, it tends to leave a permanent kink and a weak spot in the tubing, and it is not abrasive resistant, meaning you would not polyethylene tube as an airline to an air tool. Those airlines end up laying on the floor, and poly does not take well to being walked on or hand-trucked over.

Reader Questions About Polyethylene Air Tube

Using CPVC or PEX pipe for compressed air pipeline

by Jack Waters
(Blairsville, GA, USA)

I am near to the point where I will have time to run pipes to carry my compressed air around to all parts of my home shop. I had planned to use rigid copper, as I know the manufacturers recommend against using PVC. I also know that PVC is not used inside houses for waterlines. However, PEX and CPVC are both considered safe to use inside houses for waterlines. Therefore, I wondered if they can be used for my compressed air system. I plan to use no pressure higher than about 150 pounds psi.

Answer

Jack, the simple answer is NO, don’t do it.

Yet there are new plastics being developed that might, and I emphasize might be suitable.

Before you take what might be a dangerous decision, I recommend that you note the pipe manufacturer’s name off the pipe, email them this same question, and keep their answer on file if they say yes. In that way, you have redress should the plastic fail.

If not copper, opt for rubber/vinyl (not just PVC) hose with barbed fittings. Relative low cost, forgiving with misalignment, and won’t rust.

An anonymous contributor thinks there is no problem:

What’s the worst that could happen? Air leak OMG someone call 911, I mean come on. If it leaks it probably gonna be at a connection. Is an air leak even at 100psi really gonna be catastrophic?

___________________

If you are in the room when a plastic pipe full of compressed air explodes and it sends shards of plastic into you and those around you… I don’t know, wouldn’t you consider that the worst that catastrophic? Ignorance is bliss. Be blissful then, friend.

Charlie writes in and agrees:

I would strongly caution against using PVC to plumb your airlines.

Years ago, I worked in an auto paint shop in Orlando, FL that was plumbed with PVC. One hot summer afternoon, the line exploded for no apparent reason about 20 ft away from me and it was like a bomb going off. Everyone in the shop came running thinking a car had exploded. Nobody got hurt, thankfully, but there were shards of PVC all over the shop and all work ceased since there was now no air pressure to run tools or paint cars. Bottom line – don’t use PVC for compressed air pipes.

Polyurethane Compressed Air Tube

Polyurethane is sometimes used to plumb air to valves and air cylinders too, as it is softer, more malleable and able to be bent in tighter circles without kinking.

It is also more expensive than polyethylene tube.

Polyurethane also may have some leakage or “blow off” issues when used with some types of instant fittings that aren’t designed for a soft-surfaced air line.

The ‘natural’ polyethylene air tube is rated to handle industrial air pressure in the 120+ PSI range in normal ambient temperature environments.

Colored Polyurethane Tube

Colored forms of P.E. tube get more expensive and are sometimes harder to find. Why consider them, then?

Plumbing a machine with dozens of air valves and air cylinders with colored tubing makes problem diagnosis easier on a larger machine. For example, you might consider making the cylinder extend air lines one color, the retract another. Or, if you have pneumatic logic on a machine, you might make all of the control air lines one color, and the power air lines another.

In this manner, it’s easy to trace a specific air line from the source to its air component, and thus make it easier to determine if there is a problem with air flow to that unit.

Nylon Compressed Air Tubing – Pneumatic Tubing

Nylon pneumatic tubing is a more expensive alternative to polyurethane, but comes with a range of enhanced capabilities including:

  • Increased operating pressures
  • Increased chemical compatibility
  • Harder walls bring better compatibility with fittings and fixtures

Rapidair are leaders in compressed air tubing and piping, and their Rapidair flagship range is comprised of nylon pneumatic tubing.

Copper Pipe For Compressed Air Systems

In my opinion, after poly tube, the next best plumbing material for the home or small shop is copper pipe.

Yup, the same copper that is used to plumb the water lines.

If you have any experience with soldering copper is really easy to work with, has lots of fittings to convert from soldered copper to threads for installation into components, and it too does not rust.

If soldered properly copper fittings and joints should never leak, giving the user potential to save the energy costs many other compressor owners waste to the atmosphere through the airline and fitting leaks. It used to be a lower cost.

A drawback now is that copper prices continue to rise, making an all-copper installation quite expensive. And, if you cannot solder, installing leak-free joints with copper can be a bit of an issue.

Rubber Hose For Compressed Air Line

Next, consider using a rubber hose, if you can get one large enough for your airlines.

Whether hung on the wall, running along with the ceiling, or laying on the floor to be stepped on or hand-trucked over, rubber hose is resistant to abrasion, some of it is very resistant to chemicals in the working environment, and it plumbs around corners just fine.

If you need a tight elbow, a couple of gear clamps, and a 90 degree barbed fitting sized to suit, and you are tight to the corner. Need more airline; the same scenario. A couple of gear clamps and a straight, male-to-male barbed fitting, and the hoses are connected.

There are some potential problems with a hose.

Like polyethylene tube, rubber hose may have some size constraints if your air mains need to be larger than 3/4″.

The rubber air hose festooned around the walls of the shop may not look as professional as you would like.

And, if you don’t put the barbed fittings and gear clamps on properly, you will get air leaks. Inspect the fittings after a short while to see if a change in conditions in the plant has allowed any of those fittings to leak. Compressed air is the most expensive industrial energy form there is and you will not want to waste it.

Galvanized Pipe For Compressed Air Systems

On the airside, I did get many responses when asking folks about the use of galvanized pipe in air systems. Here is one response, sent in by Paul Pearce.

“I am a Millwright & here is what I think about galvanized pipe for compressed air systems. 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 inspects 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.

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.”

Paul is pretty clear how he feels about galvanized pipe for compressed air, and I tend to agree with his analysis.

You know, I don’t know of anyone that’s using a galvanized pipe as a compressed airline. 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.

Question from reader: How does galvanized pipe rank for compressed air plumbing?

by Tony
(Fayetteville, NC)

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.

Answer:

My response: 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.

Reader Negative Views on Galvanized pipe for plumbing compressed air

Tony, I’m new to this whole compressor pipe 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.”

Answer

My response: 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.

Response by 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.

and 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.

Response by David:

You’re right the bottom line is in air quality. If you just using the the air to blow off and clean machinery the galvanized is a perfectly good solution not to mention cost effective.

Look at it this way, galvanized 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 galvanized. If its installed properly then you should get many years of use out of it before there is a problem.

Also keep in mind the environment 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 corrosion problems that galvanized has when exposed to moisture it oxidizes and pinholes develop.

I know places completely piped in galvanized pipe with no problems because it is used for just cleaning off equipment. If your using air for pneumatic cylinders and other related applications then yes copper is the best alternative.

Response by anonymous:

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.

Response by Anonymous:

Galvanized pipe not as good as it once was?

Galvanized pipes are not that bad. The thing is that galvanized pipes are not as good as they were in the past…

In my backyard I have lots of galvanized 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… because they rust almost instantly when exposed to moisture, rain etc., stuff just isn’t as good as it was in the past…

Response by Anonymous:

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 systems:

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.

Response by Anonymous:

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.

For your safety and longevity of your systems, we’re summarising materials that we believe to be less suitable for compressed air lines. We’ve also included some user negative views on compressed air piping materials. As always, consult a specialist before acting on any advice and please be aware of my information disclaimer here.

Composite / Plastic Air Pipe

There are some companies that build a composite plastic piping system for compressed air. I know that this product is not approved for use in every state, province, or country, so check carefully.

I am against using PVC and CPVC plastic pipe for plumbing compressed air regardless of the source. As ambient temperatures rise, the pressure rating of plastic pipes drops dramatically, and may quickly fall below standard industrial compressed air pressures. Should the plastic pipe fail, rather than springing a leak, the plastic will shatter, sending shards in every direction.

I am saying do not use any plastic pipe for compressed air unless you contact the manufacturer of that plastic pipe, and get approval in writing from them that they recommend the use of their pipe for compressed air. No letter? Do not use it!

Ultimately, what pipe you use for your compressed air pipes is up to you, your budget, your installation-skill-level, and how much air you need for your equipment.

PVC piping

We do not recommend PVC pipe for compressed air, it could be catastrophic. PVC’s burst threshold lowers the hotter it gets and when PVC lets go, it often shatters, and anyone and anything around could get shredded. Readers have had PVC pipes swell and burst on them.


Anyone else have any experience with galvanized pipe for air lines? Please add your comment here along with photos to help others help you with your compressor and equipment problem!


New comment? New question? Please add it here along with photos to help others help you with your compressor and equipment problem!