Advice On Plumbing in Compressed Air Line

[Tractor Seabee]

I have seen pictures of two failures under a Navy Air Station parking apron. They were 8" lines one was HDPE and the other PVC in 3' of earth under with a 10" concrete apron over the fill. They tore 6' diameter +/- holes in the concrete and caused several $M damage to several aircraft from the shrapnel. The investigation determined the cause was oil contamination. My company installed a new system. The specs required schd 40 welded steel. We convinced them to acept schd 10 SS. They originally used the HDPE and PVC to eliminate cathodic protection but learned a bitter lesson. Luckily the disaster happend when no personnel were around. Lots of energy in an air system. When I went to welding school we had a kid drop an oxygen bottle (large one) and break off the valve. That bottle took off like a roket and tore out an 8" concrete block wall went 50' and smashed the sideiof the instructors new cadlilac.

 

[adjusterr]

I had my Plumber run black iron pipe throughout my two shop buildings. He hung the horizontal pipes with a fall so moisture would drain to one location then installed a down line with a drain. Every vertical line has a drain as does the compressor. You cant imagine how much moisture collects in the system, drain often.

 

[forgeblast]

adjusterr what size pipe did you use?

 

[wedge40]

I've heard that you shouldn't use PVC, but I've never seen anybody post "first hand" info or an accident report or newspaper article about someone being hurt or killed by pvc "exploding". I have how ever seen lots and lots of posts about first hand info from people who use it. I'm not saying it cant happen, but it's like the oxygen bottle going through the wall when the end was knocked off. Watched an episode of mythbusters and they did make it happen, but it took a lot of work and actually had to guide the tank along a rail system to go through a block wall. They also found it took way more force then they thought it would to snap off the end of the tank.
Just my thoughts on PVC thing.

Wedge

 

[lilranch2001]

I've heard that you shouldn't use PVC, but I've never seen anybody post "first hand" info or an accident report or newspaper article about someone being hurt or killed by pvc "exploding". I have how ever seen lots and lots of posts about first hand info from people who use it. I'm not saying it cant happen, but it's like the oxygen bottle going through the wall when the end was knocked off. Watched an episode of mythbusters and they did make it happen, but it took a lot of work and actually had to guide the tank along a rail system to go through a block wall. They also found it took way more force then they thought it would to snap off the end of the tank.
Just my thoughts on PVC thing.

Wedge

Take a piece of PVC out and even with a minor amount of force, swing it against a tree.
See what happens
Now, also take into account that you may have 4-7 atmospheres contained inside that pipe, and the explosive decompression that will happen when something breaks that piece of pipe............

I dont know, I guess it is just a gamble I refuse to take, been around way to much compressed gases in my life to take that chance.

 

[Qapla]

I am not going to speak as to if one should/shouldn't use PVC for air ... however, as soon as I saw the thread title I knew that the PVC issue would come into the discussion.

 

[SpringHollow]

There are plenty of cases of pvc failing in industrial situations where they are documented because OSHA gets involved. The reports include pictures. I saw them several years ago when i was planning my system. Hard to argue with those even if you do not want to believe all of the people who are admitting their mistake to prevent others from getting hurt.

I run low pressure schedule 40 pvc lines for a large aquarium system. I cut it with the common pvc pipe shears. New pipe feels soft and cuts very easily. Old pipe often shatters. This is old pipe that has never been used. Now add heat and oil to the mix.

Plenty of people who have used PVC without problems. If it is a 1 in 1000 risk, do you want to risk being the 1? There are lots of risks that are hard to avoid. This is a simple risk to eliminate. If you want an easy way but want to flaunt the regulations, you could use PEX perhaps. I have never heard of that shattering. Actually, come to think of it, I have a few pieces installed in my system. But I know it is not rated to be used. There is one that is stamped appropriately but I do not know if it differs only by the stamp.

I also hope all those who argue it is fine to use PVC can live with themselves when someone follows their advice and gets hurt.

 

[SpringHollow]

Took 5 seconds to find this link: 19880520 The Use of Polyvinyl Chloride Pipe in Above Ground Installations

 

[bcp]

Brain Teaser 15

 

[wdchyd]

I have had issues with using black iron threaded pipe years ago but it was in the building codes a long time ago.....the issue I had was the condensation of compressed air was making rust inside the pipe......resulting in rust fragments coming out ruining air tools if they were not filtered and oilers installed

I can't say I've had any PVC or plastic pipe in my shop but I'd wonder if there was a fire wouldn't the pipe melt from the heat and explode?? and fan the flames right where you don't want them??

I use copper (the heavier type-L) anchored properly with drop legs in the entire shop except for a piece of hyd hose (not regular air hose) from air comp to the wall (to reduce vibration) and have always been happy with the results....... and it looks very professional looking for the local authorities and insurance inspections......and the condensation (no rust) doesn't bother the air-tools and blow-guns

I realize using plastics will work but I can't take the gamble if there is even a slight chance of catastrophic failure......I wouldn't want to work for an employer that would cut corners like that so why would I take short-cuts and expose others to those potential hazards

:2cents: