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panky99 03-01-2012 07:39 AM

pipe pvc or not
can a person use pvc sch 40/80 will the joints hold?

T-bucket23 03-01-2012 07:50 AM

what do you want to use it for. If you are talking air, dont do it. It is dangerous

johnnyg 03-01-2012 07:55 AM

PVC is made for low or no pressure water, like under your sink to drain the water.

Old Fool 03-01-2012 04:47 PM

PVC sch 40 pipe is definately rated for pressure

PVC shc 40 pipe for the most part is not rated for compressed air at any pressure.

The oils in compressed air are known to degrade the pvc material and make it brittle.

A pipe with 100 psi of compressed air in it is a potential bomb. If the material is adequate, nothing happens. If it cannot contain the pressure explosive decompression happens sending sharp plastic shards all over heck.

A pipe filled with water to a pressure of 100 psi is not a potential bomb. If the material is adequate , nothing happens, If it cannot contain the pressure, it splits and water sprays out as a mist or a quickly depleted stream. No explosive decompression will happen.

Many do it, they take the risk. For me it is not worth saving a hundred dollars.
40 years in the trades to see to many failures due to improper installations to think otherwise.

I replaced a large steam tube bundle at a major hotel in down town Seattle.
The city of Seattle provides the steam to the building , at which point the building owner operates the system.
This system had 4 relief valves on it, which if all were functional they would have been providing adequate protection.
BUT someone had used wire tyes to tie down the relief arm on one of the reliefs. When asked about it the building mtce people said it was done because it leaked and made the room to hot.
That was only half of it, when removed - a second relief valve was found to have had the temp probe sawn off of it so it would fit into a pipe.
50% of the safety function of that system was disabled and had ran for who only knows how long without a news incident.
The main steam valves were shut off upstream of the reliefs until the full system repairs and corrections were completed.
No way we were going to work in that room, or that building under those conditions.

Same thing applies to the air system at my shop. No PVC for me.

johnnyg 03-02-2012 05:56 AM

I wouldn't use it for steam either it would melt.

Old Fool 03-02-2012 07:52 AM


Originally Posted by johnnyg
I wouldn't use it for steam either it would melt.

Now that's funny :thumbup:

MARTINSR 03-02-2012 07:57 AM


Originally Posted by panky99
can a person use pvc sch 40/80 will the joints hold?

Go to your local hardware store and price out galvanized pipe, it doesn't cost that much more and it is the right way to go.


RPM 03-05-2012 05:55 AM

I have pvc in my shop for over 12 years now. No problems at all. It runs 120 PSI everyday.

Schurkey 03-05-2012 06:20 AM


Originally Posted by RPM
I have pvc in my shop for over 12 years now. No problems at all. It runs 120 PSI everyday.

And if it explodes, the PVC shrapnel won't show up on your x-rays.

You have a shop fire that melts a little hole the pipe, you've just created a blowtorch.

johnnyg 03-05-2012 07:21 AM


Originally Posted by Old Fool
Now that's funny :thumbup:

I thought you would get a kick out of that!! :thumbup:

oldred 03-05-2012 07:44 PM


Originally Posted by RPM
I have pvc in my shop for over 12 years now. No problems at all. It runs 120 PSI everyday.

And you think that makes it safe? The longer it's up the more likely you are to have a serious accident, 12 years without an incident only means you were lucky not safe and the older it gets the more likely it is to rupture. Do you have any idea how much damage a ruptured PVC pipe carrying 120 PSI of air can do? These things don't just spring a small leak or simply break they usually rupture along several feet of length and throw razor sharp shards that will fly in all directions and can be lethal 25 to 30 ft away or even farther, like Schurkey pointed out if you are hit by these pieces of shrapnel embedded pieces will not show on an X-ray. There have been many serious accidents resulting from using PVC for airline and because some people still insist on using it there will quite likely be more accident victims, don't kid yourself you could be one of them. If you want to continue using PVC in spite of the WELL KNOWN hazards that's your business but please don't come here and tell someone else it's safe because it most certainly is not!

dinger 03-05-2012 11:45 PM

Oldred has it right on. DO NOT USE PVC PIPE FOR AIR! I have personally seen 3 failures on the same location, they were lucky no one got hurt, especially me, cuz they were told and then if I were hurt, that business would have my name on the business license as owner. Stupid! I finally threatened to have the county come out and inspect it, the contractor then did the right thing and changed it out to cast.

Vegaguy 03-06-2012 01:58 AM

I have seen and heard pvc fail in use as air lines and this was in a GM dealership. It was temporary due to a fire in the main shop but it failed at 110 psi. It sounded like a bomb and sent shrapnel everywhere and luckily no one was injured from it. I will never use pvc for air lines. Use black iron pipe.

Old Fool 03-06-2012 07:05 AM

last 2 posts mention "cast" and "black iron", do not think this means you can use black cast iron. It is drain pipe.

Black iron pipe is steel, not cast.

MARTINSR 03-06-2012 07:56 AM

Yes and you want galvanized not black. Black is for gas not water, unfortunately compressed air is full of water so it shouldn't be used.


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