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Carld
09-18-2006, 09:49 PM
I may have started a hornets nest on Practical Mach. Someone posted his new copper air lines and I casually mentioned my pvc air lines. Then the flurry of posts started.

I use 3/4" schd 40 pvc for air lines at 120psi. I have had the system for about 13 years now. Does anyone else use them? I have already googled for air lines and pvc manufacturers specs. The pvc is impervious to most chemicals and oils according to the Charlotte site and good for 480psi. It said they will withstand extreme pressure beyond the rated pres. but to not use as air lines.

Evan
09-18-2006, 09:57 PM
PVC is ok to use if it is shielded so it can't be bumped and if it blows the shrapnel is contained. Otherwise it is prohibited in many jurisdictions.

JCHannum
09-18-2006, 09:59 PM
The normal PVC Schedule 40 & 80 used for water piping if used for compressed air will at some time fail catastrophically. It is not a maybe, it will fail, and when it does, it usually bursts with needlelike shrapnel being the result.

There may be some plastics suitable for shop air, but PVC is not permitted.

rsr911
09-18-2006, 10:00 PM
The trouble with PVC is that it's easily cracked and when under pressure sends PVC scrapnel everywhere. I use copper both at home and at work. I had a guy hit a copper airline at work with a forklift, it bent and leaked no explosion. Copper is more expensive but cheaper IMHO. That said in a home shop with the PVC tucked out of the way of getting crushed I suppose it would be fine. I've seen shops with black iron pipe, to me it's even worse than PVC, it's difficult to replace, repair or add drops and it's seam welded so it ruptures if crushed.

Todd Tolhurst
09-18-2006, 10:03 PM
According to the Plastic Pipe and Fittings Association (http://www.ppfahome.org/pvc/index.html/):


PVC piping systems should not be used to store and/or convey compressed air or other gases. PVC piping systems should not be tested with compressed air or other gases either.

Seems like they ought to know.

Fasttrack
09-18-2006, 10:03 PM
hey wait a minute...isnt black pipe used for natural gas and propane? what other kinds of metal pipe are there for air? galvanized i guess...

<edit> i guess the keyword there was "iron" ? Not trying to be a jacka** or anything, just wondering!

Bill Pace
09-18-2006, 10:05 PM
I too have had plastic installed for MANY years (prob 20?) and no problems. Few week ago I wanted another drop, so went to my local plastic pipe ONLY supplier to get the handful of ells, tees, etc and it came up that I was gonna run air....guy looks at me, kinda winks, says "you KNOW you aint supposed to use this for compressed air?", so I say, as usual, yep I sure do. We went ahead and talked a few mins and he says he sells a LOT of pipe for air. But, yeah, for some reason its not "approved"

And then theres the cost..........terrible expensive, and HARD to work with...HAH!!! Love that plastic pipe......I think that extra drop cost me 8-9 bucks and took bout an hour.

JCHannum
09-18-2006, 10:14 PM
If you have ever seen a failure, you would waste no time in removing the pipe.

Standard copper pipe with sweat fittings is slightly more expensive, and installs just as easily. Compared to your vision, the few extra dollars is well worth it.

Black iron pipe (which is not iron), galvanized pipe or copper will split of over pressured. PVC explodes. Believe it.

lane
09-18-2006, 10:21 PM
spent 23 years in shop with pvc schedule 80 air line and use it in my own shop no problem.

Evan
09-18-2006, 10:26 PM
http://www.osha.gov/dts/hib/hib_data/hib19880520.html

jaybird
09-18-2006, 10:28 PM
Go with 3/4 inch copper pipe and copper tubing for all of your air lines. Why? For heat dissipation. Cool air holds less moisture and your air tool and your plasma cutter will be much happier.

JCHannum
09-18-2006, 10:36 PM
I have worked with several plant air systems and have been forced to use PVC on a couple of occasions when the bean counters or purchasing agents got involved with the cost aspect.

It can work, but it has to be well supported. I have had success with installations where the piping was installed in an obsolete piping run of a larger diameter. In these cases, the PVC was fully supported, and not subject to mechanical stress, only pressure.

I suspect some shops with piping under 1" or smaller may not experience the problems of larger diameter systems, especially if it is well supported. The installation is still a guessing game, and the stakes of guessing wrong are too high. I would never recommend it. I have seen many more failures than successes.

jmm360
09-18-2006, 10:42 PM
1980, my first job out of school, we had PVC piping for 120psi air. I thought nothing of it, I had also never seen an industrial accident at that time. I know a little more now, I would never go near a PVC air line again. A couple more bucks for the safety of everyone who enters the shop is money well spent.

Milacron of PM
09-18-2006, 10:48 PM
I was in a woodworking facility in the mid 1980's when the PVC air line shattered. Nobody was hurt but it sure scared everybody. And this was a 20,000 sq ft building with PVC airline over the whole place....had to replace it all. Installation was 18 feet up, so nothing hit damaged it before the failure, but I don't remember the schedule or how well it was supported, which could have been a factor.

Humorously the same shop had PVC for their dust collection, and that didn't work longterm either due to major static electricity problems caused by wood dust flowing at high speed thru the piping !

MTNGUN
09-18-2006, 11:00 PM
I worked at one place where PVC was used for the air. It was a special kind, green color, schedule 80, and supposedly more resistant to oil. This particular PVC pipe was made exclusively for compressed air. There were no failures with the green pipe. One time a very old white sch 40 pipe broke at a threaded male fitting. That pipe was unsupported, putting a lot of stress on the fitting. There were no shards, it simply broke in two.

I used CPVC (because I had some left over from another project) at my old shop. Never had any problems. The CPVC was run over head, all the drops were flexible hose, so even if the overhead line had burst, it would not have been close enough to inflict damage (PVC projectiles would lose velocity very quickly).

My new shop has PVC running underground from the outdoor compressor to the shop. I used the PVC for corrosion resistance. I'm certainly not worried about the underground pipe hurting anyone. Galvanized iron will be used inside the shop.

x39
09-18-2006, 11:24 PM
A good friend and business partner of mine had PVC air lines in his shop up until a few years ago when the whole works grenaded. No one hurt, but it sure got everyone's attention. It happened during the winter (in Maine), and a good portion of the system was in an unheated part of his building, making me wonder if it may have been a result of embrittlement due to the cold.

dp
09-18-2006, 11:33 PM
This sounds like a good subject for Myth Busters. At least a home video out in a field somewhere with some pvc, an air compressor, and a fire cracker. Anyone remember that kid that made a flame thrower out of pvc pipe? That was totally nuts.

The link Evan posted earlier included this:

"I am alerting you that there is a device on the market for pressure testing product lines, used in conjunction with tank testing, which is not safe. This device, manufactured by Horner Creative Products, 413 State Park Drive, Bay City, Michigan 48706, utilizes a plastic (PVC) cylinder which is attached to the pipeline, filled with gasoline, and then up to 100 PSI air pressure applied to the cylinder."

Sounds like something a terrorist would make.

dirty old man
09-18-2006, 11:50 PM
All I know is the 3/4" schd 40 PVC has been in my shop for about 12/13 years and the only problem I have had was when I got a portable 500watt halogen too close.
And I have a helluva lot more to do than replace pipe that's holding air just fine.
Dave

Evan
09-19-2006, 12:32 AM
Of course they are holding air. They haven't exploded yet.

Doc Nickel
09-19-2006, 01:31 AM
It's not the pressure, it's not the temperature, it's not the oils in the air.

It's the flexing.

The constant pressure cycling as tools are used, or water bleeds are opened, or the connection to the compressor is shut in each night. As illustrated here, some people get away with it just fine. Some people run regulated air through the system- 80 psi is plenty, don't need the full 120 psi- and that helps a lot.

But the fact is, it's dangerous, or at least not very safe. Your system may be working for now, and may continue to do so in the future. But then again, it could rupture the very next time you plug in a hose.

Copper is far better. Not as cheap, no, but that's irrelevant. I got an earful from you guys when I asked a while back if I should buy a new import mill or a used American. Everybody told me that it was "worth spending a little more" on the better tool, that I'd "have it for years" and the cost would end up being a pittance per day all told.

But hey, it's worth saving a hundred bucks on an air system, right?

I looked into using PVC myself. I asked around, I got the exact same answers here in this thread: some people said "hell no", some people said "mine blew up", and some people said "heck, mine's been working great for years".

I looked into the costs, and copper was going to run me a little over $150 more than PVC. Unfortunately that was a couple years ago, and copper prices have gone up since then. But even if it's $300 higher or even more, in my opinion, it's worth every cent to know it's a better system than PVC.

Still not convinced? Read all these articles, or ask around. Tally up how many PVC systems have had a failure or blowout versus how many copper systems have failed.

Doc.

Frank Ford
09-19-2006, 01:42 AM
I used PVC for a few years, and had continual problems with leakage. Cracks formed at stress points, and eventually I got the point - skip the PVC. Taking a cue from an old pal, I redid my entire shop with the simplest and easiest of all systems - rubber air hose and barb fittings with worm clamps. So easy to do! I could redo the entire small shop in about an hour (exaggerating, of course, but you know what I mean). No leaks, no problems. . .

topct
09-19-2006, 08:33 AM
They are building a couple of duplexes behind where I live.

They are using some kind of flexible water lines in them. Blue and red. Without touching the stuff it looks like that nylon? stuff that I've seen used for oil lines. Only this is about the same diameter as copper or pvc.

If it came in a larger diameter? It sure looks like a quick way of plumbing a house anyway. No elbows, they just bend it up, around, and wherever they want to tap in, just slice it and install what looks like a compression fitting.

I think this is it,
http://www.lowes.com/lowes/lkn?action=howTo&p=Improve/PEX.html

john hobdeclipe
09-19-2006, 08:50 AM
There's another aspect to an air line failure besides the shrapnel. If you are too close to a ruptured air line, and are in just the wrong place, you can easily lose your eardrums, or your sight. Compressed air at 120 psi or so can do a lot of damage to you all by itself, in addition to whatever damage is done by flying shards

If you had a 3/4" pipe, charged with a continous supply of air at 100 to 150 psi, and blowing it all out the open end, unrestricted, would you stand directly in front of it? Would you put your face in front of it?

PVC pipe is too brittle, to sensitive to impact. It may work just fine if everything in the system and it's environment is well supported and well protected, but I would never take a chance on it. Your air system needs to be designed with accident scenarios in mind. What if someone jerks on an air hose? Or bangs into the air line with a forklift or a heavy piece of material?

The time and money saved by using PVC instead of copper won't come anywhere near paying for even the slightest injury should the air line fail.

Evan
09-19-2006, 09:25 AM
Believe me, you don't want to lose an eardrum. I am still deaf in my right ear since a month ago and the only air line that failed was to my nose.

I also use plain old rubber air hose for the few lines that I run in the shop. I have three compressors and the one that supplies the downstairs shop is in the garage. It a big old one I built with an 40 gallon tank and I regulate it to 50 psi since all I need the air for in the basement shop is blowing chips out of the lathe spindle and cleaning tapped holes and similar. If left unused it runs maybe once per week from leakage.

JRouche
09-19-2006, 09:26 AM
PVC is dangerous. I use 3/4" copper line. JRouche

JRouche
09-19-2006, 09:27 AM
Dupe.......

wierdscience
09-19-2006, 09:35 AM
I nearly lost an eye to pvc airlines.The pipe might be good,but the fittings suck.Someone in the shop was using a blowgun to cleanout some chips in a mill table.A 3/4" elbow blew off completely,went past my right temple and knocked a fisheye in a plate glass window.

If you could find sch 80 pvc and used threaded fittings it might be okay,but black or galvanized pipe is much better and cheaper than copper these days.

I have seen the red and blue water tubing used,but it isn't that great at pressure.Most times over 50-60psi it starts to ballon.It won't pop,but it looks like it swallowed a rat:D

Orrin
09-19-2006, 10:03 AM
In the 10-15 years I've been in the Internet, the topic of PVC air lines comes up about once a year.

Every time it's the same story: In spite of warnings against it, folks who have installed PVC air piping won't admit they've made a mistake and stubbornly stick to their guns.

Most certainly, there are PVC air systems that have served for years without failure. That doesn't mean it is safe. What it really means is this: Every day the odds of failure are climbing.

Plastic ages. Some day...

Regards,

Orrin

Mcgyver
09-19-2006, 10:44 AM
In the 10-15 years I've been in the Internet, the topic of PVC air lines comes up about once a year.

Every time it's the same story: In spite of warnings against it, folks who have installed PVC air piping won't admit they've made a mistake and stubbornly stick to their guns.

Most certainly, there are PVC air systems that have served for years without failure. That doesn't mean it is safe. What it really means is this: Every day the odds of failure are climbing.


good post, I too wonder what all the "i've had it for 20 years...." posts are really saying. ... Is that it hasn't yet exploded offered as proof that it won't? that they're disagreeing and stating it is safe practice? or maybe just I'm a daredevil and you're all pussies?

It's not bad that these things keep coming up, for each of us there was a first time we heard it. My person near death experience, saved by the internet (perhaps not an exaggeration) was being all set to spray paint with Imron :O autobody supply store sold it me without a word or qualification or caution.

A.K. Boomer
09-19-2006, 12:06 PM
I think the bigger the line the more you have to worry about it, i run 1/2" PVC from the garage to the basement at 150psi. its rated to 480 or 600psi, i was going to regulate it but that hasnt happend yet, nothing but a one foot section behind my mill is exposed so i really dont care if it breaks as im always wearing safety glasses when im working, To me there are much bigger issues in the world --- iv seen 3/4" pvc do just fine for 2 decades at this pressure in a friends car repair shop, If mine blows and somehow shoves a peice of plastic coupling through my forehead i will just consider it gods will, i also have a small section in the basement overhead that i walk by on occasion but dont plan on looking directly up at it and beating on it with a hammer while having my face a couple inches away ----- Im at altitude so i milled the heads on my air compresser, everything i do is "hopped up"
even my hoover vacuum has an added switch that kicks in a extra set of windings for those stubborn little dirt spots on the carpet, Small diameter PVC pipe is a wonderful thing if not just for experimenting with how much pressure it will hold before it blows, you guys worry to much...

Evan
09-19-2006, 12:07 PM
PVC has one main problem. The glass transition temperature is 81C (177F). That means in shop use it is a glassy amorphous solid with brittle fracture characteristics. This is temperature dependent with the rupture strength decreasing with temperature. The colder it is the easier it is to shatter it.
Some plastics are much better in this regard such as LDPE with a glass transition temp of -30 and polyprop at -20.

The rated pressure that the system is run at is not the maximum pressure developed. When air is flowing at high volume at or near the maximum pressure from the receiver and the air use is shut off suddenly a pressure spike is produced that can be several times the nominal pressure in the lines. This is caused by the momentum of the air as it moves through the lines at high velocity and is suddenly stopped. It's exactly the same as water hammer since the air is acting like a fluid. Rapid valve closure creates an acoustic wave that travels back through the pipe to the air receiver. This places extra stress on the pipe along it's entire length.

PVC pipe is subject to eventual fatigue failure regardless of the amount of stress applied. The number of cycles it can withstand is nonlinearly related to the degree of stress per cycle. For large repetitive stresses it can be a very low number, in the thousands of cycles.

The greater the air flow and the more rapid the shutoff the greater the stress and the fewer cycles the pipe will withstand. It is this variability in use that can make one installation fail and a similar one last a long time. All it may take to produce a catastrophic failure one day is to use the system in such a way that creates a large pressure spike.

LarryinLV
09-19-2006, 01:19 PM
You can read the OSHA position on commercial luse of PVC to transport gas here:

http://www.osha.gov/dts/hib/hib_data/hib19880520.html

However, I recall reading a decade or two ago where most commercial incidents and studies were using PVC of 1" or larger and that the use of 3/4" sch. 40 in the typical home environment (~125 psi) where short runs were used, the amount of compressed air available for a catastrophic incident were dramatically reduced. Of course I can't seem to find that now.....

It seems that those with PVC (and yes, I plumbed a home shop with it once)would see this as an opporltunity to justify some really bitchen' looken' copper in the shop.

Or at least start changing to ABS, which is approved.

Alas, my shop now has 3/4" black pipe - but I'm thinken' that copper drops would be really cool

HTRN
09-19-2006, 03:26 PM
I worked at one place where PVC was used for the air. It was a special kind, green color, schedule 80, and supposedly more resistant to oil. This particular PVC pipe was made exclusively for compressed air. There were no failures with the green pipe.

It's called Chem-Aire (http://www.nibco.com/cms.do?id=2&pId=14). It's not too badly priced - Ryan Herco (http://www.ryanherco.com/Auto/SECindex.cfm?FAM=175&SEC=165) has probably the largest selection of it.


HTRN

HWooldridge
09-19-2006, 03:56 PM
Although PVC is one of the better materials at resisting degradation, all common plastics lose their "plasticizers" or bonding elements over time. I worked in the molding business for many years and one of the best materials at resisting UV degradation was grey PVC, which is why it is commonly used on telephone J-boxes. However, none of these apps contain pressure to the tune of 90 psi or higher.

For my money, black or galvanized pipe is the way to go. I have my compressor in the hay barn to cut down on the noise with a secondary tank in my shop and 3/4" pipe connecting it all together. A couple of years ago, I bought a two-stage and swapped it into the system so pipe and tank pressure went up to 175 psi (although I still regulate to 90 psi for my tools). I had no concerns about doing this with steel pipe but I might have second thoughts if I had used PVC for the initial installation.

IOWOLF
09-19-2006, 05:59 PM
OK, I am bad also, going on 12 years with PVC.When it kills me you guys split up my stuff.

Evan
09-19-2006, 06:02 PM
I'll take that share your grandma gave you. :D

HWooldridge
09-19-2006, 06:32 PM
OK, I am bad also, going on 12 years with PVC.When it kills me you guys split up my stuff.

Some folks drive on bald tires...;-)

HTRN
09-19-2006, 07:31 PM
For my money, black or galvanized pipe is the way to go.

Baaaad idea - With the relatively high moisture levels of compressed air, it eventually rusts the inside of the pipe, which you'll wind up putting into all you're air tools, paint guns, sandblasters, etc. Copper, on the other hand, corrodes much, much less.


HTRN

lazlo
09-19-2006, 08:19 PM
With the relatively high moisture levels of compressed air, it eventually rusts the inside of the pipe, which you'll wind up putting into all you're air tools, paint guns, sandblasters, etc. Copper, on the other hand, corrodes much, much less.

A friend and I helped each other build similar air systems for our shops last Winter -- I used copper, he used black pipe.

The copper was a bit more expensive, and it was more work to put together (since you're soldering instead of screw-fitting), but installing black pipe is a nasty job -- you look like you came out of a coal mine by the time you're done. It was also a PITA to find leaks on the screw-fittings on the black pipe, it was a lot easier to debug the soldered copper.

We used the same 2-stage IR compressors, and I honestly can't tell any difference in performance between the two systems (supposedly the copper pipe has lower fluid-dynamic resistance due to the smooth walls). But I do have my compressor always turned on, and it never cycles (there's no air leaks in the system), and we were never able to get the black pipe setup that air-tight.

Is PVC really all that much cheaper than copper or black pipe?

mochinist
09-19-2006, 08:30 PM
You guys just wait till you hit your pvc airlines with one of your jarts, then the s h i t will hit the fan.:eek:

rsr911
09-20-2006, 12:19 AM
When I installed the new system at work I ran 150' of 1.5" copper and about 200' of 3/4" copper to tie into the old copper system. I have a ball valve shut off at each machine and if the ball valves are shut the system will not loos any pressure over a weekend. The machines having all sorts of stull like solenoid valves, air cylinder, air motors, 1/4" polyflow line etc. are the only source of leaks. I ran all that copper without a single leak and I did it in far less time than it would have take to run black pipe. In the new construction we had professional plumbers install 2" gas line and I found four leaks that I had to have them fix, the lack of unions meant taking down part of the system. Copper has all the performance and ease of use of PVC with none of the dangers. The question I have to ask is how much money is really saved with PVC in a home shop? Most home shops I've seen might have 50-100 feet total, is saving $25-50 worth the potential danger?

I recently ran copper at my dad's new home before the drywallers came in. I ran over 200' with 7 drops in the garage alone and stubbed off in the basement until he decides exactly where he wants lines down there. The garage system is a loop with a 1' slope towards the compressor, all of the drops go up before looping back down to prevent or reduce water at the drops and I think all told we spent under $200 not counting the quick release fittings, all the drops have a ball valve shut of as well as separate shutoff for the garage and basement.

The builder who is a car guy asked my father who designed the system (me) then asked if I would be willing to design and install a system in the next personal home he builds. He also took pictures with my father's permission and is looking into offering air systems as an option on new homes. This is my father's dream home and he chose one of the best builders in the area, do you really think a well known builder would even consider a PVC air system as an option on premium homes? Heck the only PVC in my fathers house is the drain pipes, no kidding.

BTW I told the builder that while I would do his home with a signed waiver I would not do other homes since I'm not a licensed plumber, he thought I was. I did offer to consult however depending on liability issues. The Boge compressor rep has brought prospective customers to our shop to see our installation I did there.

While we are on the subject, anyone know what to use for underground air lines? We bought the building next to ours and will be trenching for telephone, data, and intercom I want to bring the air over as well so I don't have to put a compressor in the new building. When I layed out the current system I left provisions for two additional rotary screws in the event the need arouse.

Evan
09-20-2006, 01:03 AM
While we are on the subject, anyone know what to use for underground air lines?

PVC is fine. :D Really. :D

If you don't want to go that route then sleeve copper inside of a larger PVC protective sheath.

rsr911
09-20-2006, 01:15 AM
PVC is fine. :D Really. :D

If you don't want to go that route then sleeve copper inside of a larger PVC protective sheath.


Actually I'm tempted to just run copper inside of PVC underground drain pipe along with the data, phone and PA wires. I figure this way I'd have a "tunnel" to pull wires or lines in the future if need be. I need to go 75' under a drive that tractor trailers drive over so I'm gonna go at least 4' deep with the trencher. Option two was to run it in underground PVC conduit.

Evan
09-20-2006, 01:19 AM
When you put it down pull a spare lightweight line you can use in the future to pull something else.

Peter S
09-20-2006, 07:51 AM
I am always astonished when this subject comes up - because no one seems to have used the "correct" plastic for the job - PE.

PE plastic pipe is sold here in NZ under several brands expressly for airlines, with a complete range of fittings, hangers etc. I have used it on a couple of extensive machine layouts.

Cal-air is one brand that comes to mind.

I can't imagine why anyone would charge off and use PVC when this stuff is made for the job, seems to be an amazing amount of ignorance around on this subject.

Evan
09-20-2006, 10:05 AM
ABS is approved for air lines, is widely available and just as easy to install as PVC. Just look for a "compressed air service" designation printed on the pipe.

HWooldridge
09-20-2006, 01:40 PM
Christian,

I have two barns and a shop that all needed to be connected so I rented a large walk behind trencher and had all the trenches cut in a half day so was able to return the machine for a 4 hour charge. I then laid a piece of 4" grey PVC with all electrical and other lines (including air) inside. Large radius elbows are better in most apps for pulling cable or copper but I used conventional 90's and J-boxes on either end so I had termination points.

Alguy
09-20-2006, 05:20 PM
The trucking industry have using plastic for more than 20 years is is not pvc but a plastic suitable for air lines in what i consider hostile conditions , it is very durable able to take constant vibration abriasion from debris from the road. It is DOT approved.. pretty tough stuff . I would consider it for some home or shop applications where vibration or installiing rigid pipe would be problem. For general shop supply lines i will used copper in my set, up i like the thermal properties of metal to cool the air. The moisture traps like cooler air wont do diddly if the air is to warm .
allen

Fueler
09-20-2006, 05:47 PM
Count me in as one of those that tried plastic and failed. 175 lb line pressure. Within the hour after installation one line blew near the ceiling. It ripped 3 square foot of insulation off of the steel sheet roof and put a big dent in it. Pretty good concussion too.
Got my attention. Ripped it all out and went with old fashioned steel pipe. I am just glad it was far away from everyone.

rsr911
09-20-2006, 08:28 PM
Christian,

I have two barns and a shop that all needed to be connected so I rented a large walk behind trencher and had all the trenches cut in a half day so was able to return the machine for a 4 hour charge. I then laid a piece of 4" grey PVC with all electrical and other lines (including air) inside. Large radius elbows are better in most apps for pulling cable or copper but I used conventional 90's and J-boxes on either end so I had termination points.


Thank You, seems I'm on the right track. I don't want to hijack the thread though. We did have an electrician at work today installing so overhead 3-phase 880 and I asked him about going under the drive with the PVC conduit, he told me no problem as long as I installed it correctly.

jontwo13
09-20-2006, 09:39 PM
About 15 years ago a company had me install 1 1/4 pvc air line ( one of these people that knows it all). I got tired of explaning and showing him things and put it the way he wanted it. I made him sign a contract stating he was aware of all the dangers and was responsible for all damages. about 2 months later one of his employees threw a pipe up in the air hit the air line. This blew out 110 feet of line they had cranked the compressor up to 190 psi. He called me to replace all the pvc with black iron. He was under the line when it exploded a 4 foot section just missed his head. After that he went with what I suggested on any job there.

rsr911
09-20-2006, 09:47 PM
I'm curious about all you guys who use black pipe. Years ago we did the garage at my father's old house with black pipe before I knew about copper and it was a major pain. We found a lot of leaks that likely wouldn't have been there under low pressure like natural gas and fixing them meant taking down large sections of pipe. To me my time is also worth money and the ease of copper just makes a lot more sense to me. Is there some benefit other than cost?

jontwo13
09-20-2006, 10:00 PM
If you know how to fit pipe you can run carbon steel as fast as you can copper unless you are running soft copper. Iron is much harder to damage than copper also. I have seen one machine that was connected with brass schedule 40 for air and water I didn't see any need other than looks.

Evan
09-20-2006, 10:14 PM
I don't understand why people are having problems sealing a black iron pipe system. I installed natural gas in the last house we owned when I converted the furnace over from oil. I used iron pipe that I had cut and threaded at the local plumbing supply and fitted it with the correct pipe dope. Before you say "hey..." the system had to hold 100 psi test pressure for 24 hours with no measurable drop, and that's with no high volume air tank connected. I had a couple of small leaks that I had to tighten up over a system with about 25 threaded ends. Even those were only leaking a few psi in 24 hours from a very small volume.

I suspect a lot of the problems may be due to poor quality threading from worn out dies or maybe crappy steel. I did that job about 30 years ago and haven't done a black pipe install since. They have changed the codes here so you can use 3/8" copper at 2 psi with step down regulators at each gas appliance. That's a lot easier to install.

wierdscience
09-20-2006, 10:15 PM
Never had any trouble running black iron pipe for air,water,steam or oil.You use plenty of compound rated for the service you are building to and it's no sweat.I use Rectorseal rated for 300lb steam service,it's a one shot for everything including solvents and gasoline.Loctite pipe compound works great too,but costs more.Air and steam are no problem,60,000 psi water is another story,but it can be done.

I know ABS air line exists,but it's hard to find here.All you can find normally is DWV vent pipe.

wmgeorge
09-20-2006, 10:48 PM
Never had any trouble running black iron pipe for air,water,steam or oil.You use plenty of compound rated for the service you are building to and it's no sweat.I use Rectorseal rated for 300lb steam service,it's a one shot for everything including solvents and gasoline.Loctite pipe compound works great too,but costs more.Air and steam are no problem,60,000 psi water is another story,but it can be done.

I know ABS air line exists,but it's hard to find here.All you can find normally is DWV vent pipe.

Ok, once again this has been covered over and over again... But OHSA will NOT allow PVC air lines in any Industrial application I know of, and I used to have a link to the page, but its gone now. Worked for a stupid boss in a company a few years ago, I refused to put in the stuff. They had another pipefitter install....it was like a bomb waiting to explode and it did. Use either black iron pipe (steel) either Schedule 40 or 80 or the heavy grade of copper tube. Some of the new plastic pipe (not PVC) is rated for compressed air, not just pressure.