Pipe dope or weld?

[kbkna]

Since it is going to SNOW here in Alabama... I am going to get some of my me-do list done in my shop. I was given numerous diameter galvenized pipes that I am going to use for my air lines. I was going to use the 1 1/2 as the main line running the lenght of 100 feet. My question is should I dope the joints together or go ahead and weld them. My concern is that the pipe is not made in the USA and if the pipe dope will be able to seal a leak at 175 psi. Any thoughts or suggestions will be used.

 

[Huyzel]

Weld it.. easier to fix a leak once everything is put together..

 

[Stephenw]

Teflon tape should do a good job sealing the joints. What do you mean by "weld" them???

 

[kbkna]

I was going to actually weld the pieces together.

 

[Red Green]

Welding galvenized gives off bad fumes. I think they are toxic.

 

[larry_g]

Teflon tape should do a good job sealing the joints. What do you mean by "weld" them???

Teflon tape is a lubricant, not a sealant.

lg
no neat sig line

 

[ixlr8]

Do you want to be welding galvinized pipe??
It is a bit overkill, but I put a layer of pipe dope on the pipe and the fitting, then wrap the pipe with teflon tape and then assemble... never had a leak so far. An old boiler pipe fitter taught me that.

 

[rickairmedic]

Welding galvanised metal is not a good idea . Metal fume fever can kill you .With snow outside the garage door will be closed so No welding the pipe . Pipe dope should do just fine . I am waiting though for the flaming for using galvanised for air lines . I think it may be frowned on worse than PVC.

Rick

 

[AndrewHR]

Welding galvenized gives off bad fumes. I think they are toxic.

yes they are. They build up over time and can kill you. Wear the correct breathing apparatus

 

[Stephenw]

Teflon tape is a lubricant, not a sealant.

lg
no neat sig line

It's worked well for me. I've had leaks using just pipe dope.

http://en.wikipedia.org/wiki/Thread_seal_tape

 

[walrus]

Welding galvanised metal is not a good idea . Metal fume fever can kill you .With snow outside the garage door will be closed so No welding the pipe . Pipe dope should do just fine . I am waiting though for the flaming for using galvanised for air lines . I think it may be frowned on worse than PVC.

Rick

I've installed 1000s of feet of galvanized airlines

 

[AndrewHR]

I've installed 1000s of feet of galvanized airlines

If you were welding it and wearing breathing apparatus or were fortunate enough not to breath the fumes then well done. If not the toxicity builds up over time.

 

[ratdoggy]

I've installed 1000s of feet of galvanized airlines

But you haven't welded them probably. I believe grinding off the zinc and then welding is a no no also because you can breathe the dust. If you weld in a ventilated area and keep your head out of the fumes (which is harder done than said) you probably are fine. But there is no point to it because people put pipe thread together every day with no problems

 

[littletoes]

It's worked well for me. I've had leaks using just pipe dope.

http://en.wikipedia.org/wiki/Thread_seal_tape

Teflon is for amatures! hehehe

If it leaks, it could be your threads are not cut right, or are stripping, or perhaps you've cut them too deep.

The biggest problem with teflon, folks use too much. Three wraps on the first 4 threads should be more than enough, and keep it from getting inside the pipe, or it WILL plug stuff up!!!

Threading or welding would depend if you have the dies to thread it with.

I wouldn't personally weld anything below 2", its just easier to cut and adapt to later if its threaded.

Just my opinion.

 

[kbkna]

Great info on toxic odors. I guess I will try to dope it and then take it from there if it leaks. Should I use the grey or white dope or does it not really matter.

 

[neverenoughtools]

I recommend pipe dope. Fwiw.

 

[Grumpy365]

If you were welding it and wearing breathing apparatus or were fortunate enough not to breath the fumes then well done. If not the toxicity builds up over time.

He was referring to the statement

I am waiting though for the flaming for using galvanised for air lines . I think it may be frowned on worse than PVC.

Rick

PVC can theoretically blow apart under pressure. I don't know what could possibly be the problem with galvanized air line for non breathable air.

 

[walrus]

If you were welding it and wearing breathing apparatus or were fortunate enough not to breath the fumes then well done. If not the toxicity builds up over time.

T and C pipe, Rectorseal no 5, pipe wrenches, water pump pliers

 

[ddawg16]

DO NOT MENTION THE P word....

Thread them using pipe dope.....then if you ever need to take it apart....it will be easier...

 

[larry_g]

It's worked well for me. I've had leaks using just pipe dope.

http://en.wikipedia.org/wiki/Thread_seal_tape

From your wiki cite "The use of PTFE tape in tapered pipe threads performs a lubricating function, which more easily allows the threads to be screwed together, to the point of deformation, which is what creates the seal."

I rest my case.

lg
no neat sig line

 

[littletoes]

".....to the point of deformation,"

is incorrect. The threads are tapered, like a wedge. Its gets tighter as you screw it together. If you "deform" it, it WILL leak. If you over tighten it, it WILL AGAIN, leak.

In commercial pneumatic piping systems, galvanized is preferred. Black iron pipe has to be over sized when used, because of the formation of rust on the inside caused by the moisture. This isn't a problem with galvanized pipe, nor copper pipe. Use whichever is cheaper for you!

Grade the piping for moisture removal at/to blow down locations.

 

[kams1973]

The threads are the seal....I use red loctite when I assemble air compressors. I'm sure it would work on your plumbing as well.

 

[supertooljunkie]

I have used pipe dope and TFE tape on Sch 80 pipe that was for 1200PSI hot water, and never had a problem with either. The pipe dope would set up like concrete after being "cooked" for a while, but never had a problem with leaks.

 

[larry_g]

".....to the point of deformation,"

is incorrect. The threads are tapered, like a wedge. Its gets tighter as you screw it together. If you "deform" it, it WILL leak. If you over tighten it, it WILL AGAIN, leak.

.

If at some point of the process the mating threads do not deform a bit they will not lock together. They have to deform some within their elastic limit to hold tight. Tighten beyond the elastic limit then you may have problems. Its a matter of just right and not to much.

lg
no neat sig line

 

[Torque1st]

Pipe dope all the way.

 

[SK Guy]

I would go with the pipe dope or pipe dope w/ teflon tape. Welding the galvanized..well that is a little toxic but shouldn't be fatal...I always drank lots of milk when burning a lot of galvanized pipe, it tend to counteract the effects.

 

[e-tek]

Weld it.. easier to fix a leak once everything is put together..

I was going to actually weld the pieces together.

Teflon tape is a lubricant, not a sealant.

lg
no neat sig line

It's both.

From your wiki cite "The use of PTFE tape in tapered pipe threads performs a lubricating function, which more easily allows the threads to be screwed together, to the point of deformation, which is what creates the seal."

I rest my case.

lg
no neat sig line

OMG you guys.....
They mean DEFORMATION of the actual thread tape!!! It lubes the threads until it balls up within the threads (deforming), thus creating the seal....

I would go with the pipe dope or pipe dope w/ teflon tape. Welding the galvanized..well that is a little toxic but shouldn't be fatal...I always drank lots of milk when burning a lot of galvanized pipe, it tend to counteract the effects.

FINALLY, the right answer - as far as using BOTH teflon tape AND pipe dope. You will NEVER have a leak when done this way: 2-3 wraps of tape, thin smear of dope, tighten to 90%. Allow to set for 24 hours prior to pressurizing.

As for drinking milk while welding.....I prefer Jack Daniels!!

 

[59 wagon man]

as with as tool there are different quazlities of teflon tape skip the harbor freight or homo depot . go to a real plumbing supply and get it there . if you want the traditional way ask the counterman for some "spoolwick or lampwick"
spoolwick is a single strand of thread which you wrap in the threads like teflon tape and then apply teflon paste or pipe dope. lampwick is a multi thread spool of lampwick and you can pull about an 18" piece and wrap the threads a few times. lampwick can also be easily used on plumbing waste line compression joints under a sink

 

[e-tek]

Weld it.. easier to fix a leak once everything is put together..

Why weld it? You often want to add or change the set up of your air system - I just did!

Teflon tape is a lubricant, not a sealant.

lg
no neat sig line

It's both.

From your wiki cite "The use of PTFE tape in tapered pipe threads performs a lubricating function, which more easily allows the threads to be screwed together, to the point of deformation, which is what creates the seal."

I rest my case.

lg
no neat sig line

OMG!....Are you guys drunk again??

They mean DEFORMATION of the actual thread tape!!! It lubes the threads until it balls up within the threads (deforming), thus creating the seal....

I would go with the pipe dope or pipe dope w/ teflon tape. Welding the galvanized..well that is a little toxic but shouldn't be fatal...I always drank lots of milk when burning a lot of galvanized pipe, it tend to counteract the effects.

FINALLY, the right answer - as far as using BOTH teflon tape AND pipe dope. You will NEVER have a leak when done this way: 2-3 wraps of tape, thin smear of dope, tighten to 90%. Allow to set for 24 hours prior to pressurizing.

As for drinking milk while welding.....I prefer Jack Daniels!!

Oh - and welding Galvanized pipe (which is Zinc coated) is perfectly safe, although you can get what they call "Metal-fume fever", which feels like the flu. It actually mixes with O2 to create Zinc oxide - the stuff you smear on your nose at the beach. Zinc is NOT a heavy metal, but a micro-nutrient.
It's all right here: http://www.sperkoengineering.com/html/articles/WeldingGalvanized.pdf

 

[rickairmedic]

Ok just for the ? welders ?.

http://en.wikipedia.org/wiki/Metal_fume_fever


Rick

 

[Charles (in GA)]

I don't know what could possibly be the problem with galvanized air line for non breathable air.

The flamers will start in with the "galvanize MIGHT flake of the inside of the pipe and fittings and clog up your air tools"

Needless to say, never heard of it happening.

Charles

 

[littletoes]

The flamers will start in with the "galvanize MIGHT flake of the inside of the pipe and fittings and clog up your air tools"

Needless to say, never heard of it happening.

Charles

It won't......

If black iron pipe was to be used, the rust would be a bigger problem.

 

[littletoes]

Why weld it? You often want to add or change the set up of your air system - I just did!

It's both.


OMG!....Are you guys drunk again??

They mean DEFORMATION of the actual thread tape!!! It lubes the threads until it balls up within the threads (deforming), thus creating the seal....



FINALLY, the right answer - as far as using BOTH teflon tape AND pipe dope. You will NEVER have a leak when done this way: 2-3 wraps of tape, thin smear of dope, tighten to 90%. Allow to set for 24 hours prior to pressurizing.

As for drinking milk while welding.....I prefer Jack Daniels!!

Oh - and welding Galvanized pipe (which is Zinc coated) is perfectly safe, although you can get what they call "Metal-fume fever", which feels like the flu. It actually mixes with O2 to create Zinc oxide - the stuff you smear on your nose at the beach. Zinc is NOT a heavy metal, but a micro-nutrient.
It's all right here: http://www.sperkoengineering.com/html/articles/WeldingGalvanized.pdf

Sorry Dude.....teflon was never meant to HAVE to be used with pipe dope, and da udder way 2.
You don't need teflon, if u iz gonna use pipe dope. This is just a "LAZY" trend that has been happening in the trade. If u'z arms ain't big 'nuff to pull the wrenches with a little pipe dope on there, maybe you should get another trade???

 

[littletoes]

Oh, the funny thing about THIS thread, I am, as of right NOW!.....

FIXING several air lines that the two young dudes that put it in, used BOTH teflon and pipe dope.
The main problem being, they cut the threads a bit loose....

Three (3), turns on the pipe with a fitting to test how you set the die. NOT 5.


To add; This system involves 5 big shops, operating at 175 psi. We will be changing out the two Quincey's for a big IR Scroll and 500 gallon tank for reserve.

 

[brwbier]

Teflon tape is a lubricant, not a sealant.

lg
no neat sig line

In this part of the world teflon tape is a pipe thread sealant, read the package.

 

[rickairmedic]

Oh - and welding Galvanized pipe (which is Zinc coated) is perfectly safe, although you can get what they call "Metal-fume fever", which feels like the flu. It actually mixes with O2 to create Zinc oxide - the stuff you smear on your nose at the beach. Zinc is NOT a heavy metal, but a micro-nutrient.
It's all right here: http://www.sperkoengineering.com/html/articles/WeldingGalvanized.pdf

E-Tec I consider you very knowledgable in many areas ( however ) This is one where people could be killed . Metal Fume fever from welding on Galvanised is real and has killed many people .


Rick

 

[e-tek]

E-Tec I consider you very knowledgable in many areas ( however ) This is one where people could be killed . Metal Fume fever from welding on Galvanised is real and has killed many people .


Rick

Thanks for the vote of confidence. I normally don't GUESS at stuff I post.....Metal Fume Fever is real - but doesn't kill. If a death has been attributed it is likely shrouded in maybe's.

Did you read the link??

How about these links: OSHA: http://www.osha.gov/doc/outreachtraining/htmlfiles/weldhlth.html

ZINC

Zinc is used in large quantities in the manufacture of brass, galvanized metals, and various other alloys. Inhalation of zinc oxide fumes can occur when welding or cutting on zinc-coated metals. Exposure to these fumes is known to cause metal fume fever. Symptoms of metal fume fever are very similar to those of common influenza. They include fever (rarely exceeding 102o F), chills, nausea, dryness of the throat, cough, fatigue, and general weakness and aching of the head and body. The victim may sweat profusely for a few hours, after which the body temperature begins to return to normal. The symptoms of metal fume fever have rarely, if ever, lasted beyond 24 hours. The subject can then appear to be more susceptible to the onset of this condition on Mondays or on weekdays following a holiday than they are on other days.

Galvanizing Supply Company Safety data: http://ca.wrs.yahoo.com/_ylt=A0oG75YNdCpNHh4AFBXrFAx.;_ylu=X3oDMTBybjFrcjVnBHNlYwNzcgRwb3MDNARjb2xvA2FjMgR2dGlkAw--/SIG=127g11h92/EXP=1294714253/**http%3a//daamgalvanizing.com/design/weldingsteel.aspx

There's many more - just Google it.....

 

[e-tek]

Sorry Dude.....teflon was never meant to HAVE to be used with pipe dope, and da udder way 2.
You don't need teflon, if u iz gonna use pipe dope. This is just a "LAZY" trend that has been happening in the trade. If u'z arms ain't big 'nuff to pull the wrenches with a little pipe dope on there, maybe you should get another trade???

Right back at you too "Dude". Due to the often poor threading found on black and galvanized pipe, most compressor fitting installers will use both. I worked in and plumbed many shops over 35 years in and out of the bodyshop trade and whenboth where used, no leaks where found. When only one or the other was used.....leaky leaky.....

 

[PAToyota]

If you want to see how serious "metal fume fever" can be, read the following:

SAFETY - III : A Case study
Death by Metal Fume Fever

Posthumous Demonstration by Jim Paw-Paw Wilson
http://www.pawpawsforge.com
May 13, 2005

 

[rickairmedic]

Heres one case of metal fume fever and death.

http://www.shopfloortalk.com/forums/showthread.php?t=3315


Rick