Gas pipe tightening question from a newbie

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I'm no expert on gas piping although I've done a bit of it myself. I always tighten it down just as tight as I can. I use the pipe dope specifically for gas. I was always taught that the dope/tape actually doesn't do the sealing although it helps. It's actually more of a lubricant so you can get those pipes nice and tight. Not sure if this applies to black pipe. Cheers, cc
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Smarty wrote:

Pipe dope is a lubricant not a sealer...no matter what the can says.... pipe threads are tapered they grind together just like the faces of a ground joint union....the dope just lubricates the joint so you can get the pipe threads to jam together.
Follow the directions on the can of pipe dope.... get the joint hand tight and then make about 3 or 4 turns with a wrench..... on 1 inch pipe a 14 inch should be fine but an 18 would be easier......
Are you threading the pipe yourself ??? If you are then when you thread the pipe you want to thread it till 1 thread...2 maximum threads come out the front of the die...... making longer threads makes it easier to thread but impossible to seal..... shorter threads wont allow the pipe to mate enough to make a good seal.
Put you a couple of unions in there....... you will need a pressure gauge made for gas pipe to install on the pipe...before connecting to appliance and cap the other end...then pump up the special gas gauge with a bicycle pump..... 10 psi for 30 minutes should insure safety.... soap everything during the air test...make your last connections and then after turning on the gas...check evrything again with soap.
If you feel safer...try 10 pounds overnight...but if it drops a pound or so dont worry about it.......if it drops 3-4 pounds then recheck....but 10 psis for 30 minutes is what most building officials will accept.... the gas pressure on a natural gas line is like 3-5 inches of water....think its 27 or 29 inches of water to equal 1 psi..... unless you are running a high pressure gas line....
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Also, if you do use tape, be careful that you don't overlap the end of the pipe with it. Shreads of tape can plug up jets in burners.
Bob
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There's almost some religious wars with the tape vs dope thing, really either is fine. Don't get the wrong impression from what some of the other posters have said here; pipe dope or pipe tape serves as a lubricant to allow the pipe threads to be turned together properly. The threaded end of iron pipe is also tapered, that's why it gets so much harder to turn the further it is tightened. It is indeed the threads that seal the pipe joint, but you can't count on a sound, non leaking joint without _both_ using dope or tape, _and_ torquing the pipe threads adequately.
If you do decide to use pipe tape, make sure you get some that is rated for gas. It is usually yellow instead of white, and if your work is being inspected that's what the inspector will likely check for.
--
Often wrong, never in doubt.

Larry Wasserman - Baltimore, Maryland - snipped-for-privacy@charm.net
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Lawrence wrote:

That is incorrect. Teflon tape that is designed for gas lines can be used, but it is not the best choice for the job. Pipe dope is best for a couple of reasons. Teflon tape has a tendency to shred into the pipe and becomes stuck in orifices which can cause failures in gas appliances. Teflon tape does not seal as such, but actually makes tightening the fitting easier due to the lubricating properties of teflon. The actual seal is from the pipe threads tightening against each other.
Pipe dope is your best bet, and a large pipe wrench.
Try this: take a piece of pipe and an old fitting. Using large pipe wrenches, tighten the two together until something breaks. You will find that this is not easy to do, if you can do it at all. It is easier with the smaller sizes of course, but still not too easy. Point is, it is VERY HARD to overtighten a fitting. The major problem is getting the fitting oriented correctly.
Having run miles of threaded pipe in my lifetime, I tighten the hell out of everything and rarely have leaks. You can test with the gas pressure itself. It is better to use an air test, but there are a lot of things to do to perform an air pressure test correctly.
--
Robert Allison
Rimshot, Inc.
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But then again, it's required for the inspection where I live.
Bob
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Bob F wrote:

Yes, if it is being inspected it must be air tested. But in that case, the inspector will also require a licensed installer. This guy is doing this himself.
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Robert Allison
Rimshot, Inc.
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I now have a totally finished gas line installation and no signs of leaks anywhere. I purchased (at the recommendation of this newsgroup) a gas leak detector and also did bubble testing and all seems to be working superbly. Using long 20 inch wrenches and the right joint dope seemed to do the job without any issues.
I want to thank you very kind and extremely helpful folks for all of your assistance.
Smarty
wrote in message news:cS05h.5

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wrote in message news:cS05h.5

I did it myself, and the inspector didn't have any problems with it. In fact, he was my best source of info on how to do it and how to test it properly.
Bob
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Thats a darn good question; I don't think there is much you can do except start over. This time wrap with yellow teflon tape and put some dope over that. Shouldn't leak.
If you have trouble with your joints leaking, good luck with unions.
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I'm just a wonderin' why so many joints in only 65'?
--
Steve Barker




"Smarty" < snipped-for-privacy@nobody.com> wrote in message
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Steve,
I used 10 foot pipe sections (sold by Loews and Home Depot) and needed 6 of them. These alone account for 12 joints (2 per pipe end). I actually have another 12 or so joints since there are vertical risers at the meter, going through the foundation to the outdoor generator, and then over to the generator itself. The total number of joints being prepared will probably come out to a lot more like 30 or so. I am counting actual joints but I suspect you may be counting fittings !! (:8
Smarty

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In my building code, unions are only allowed "adjacent to accessible equipment". That is, if you hard pipe an appliance, you can use a union for the final connection. Otherwise, unions are out. You can use a left/right coupling, though.
Cheers, Wayne
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Thanks Wayne,
Never heard of a 'left/right coupling.......What is it?
Smarty
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Wayne,
I wonder if unions are not allowed because they have some greater risk of failure?????
Smarty
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wrote:

Unions are much more likely to leak than other fittings. That is why codes and inspectors require minimizing them. The key is to have good clean threads, sealed with tape, dope, or both. Your inspector likely has a preference for sealers. Many novices do not adequately tighten the joints. If you are considering re-tightening one, then you probably did not tighten it enough the first time. Tighten them really tight and never back one up. Especially if you have several joints in line, you can always go whatever additional part of a turn is needed for alignment. Unless you have a really long wrench you generally cannot break the pipe or fitting by tightening it. If you do break it, it is usually easy to replace at that time. Try it on a few fittings to see just how much they can be tightened before breaking. If you are unsure of your skills, you can seal off and test sections of pipe as you go.
Don Young
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Wayne Whitney wrote:

Locating unions only at equipment is also a a requirement of our local gas provider.
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I made a test rig using a cap fitting, and tapped a hole through it for a schrader (air) valve so you can connect any air compressor, tire pump, whatever. When a tee or elbow is added on a run, I cap it off and pressurize the piping to that point, leak test, etc. The idea is that an elbow or tee can't be rotated later. When you know the run is good to that point, you can add another segment. Really high amounts of torque aren't a guarantee that the joint will be tight. I'm thinking it has more to do with getting the pipe dope pressed thoroughly into the (clean) male threads, so it is drawn into the joint correctly. I don't go all that tight, but one of your posts mentions, I believe, using a 14" wrench on 1" pipe, which seems a little light. I would maybe use an 18".
Bill

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Dope vs tape.
Both work fine IF applied properly. The difference is that dope can just be slathered on until it fills the threads, more or less. As you assemble & tighten, it moves around to fill voids.
Tape must be applied using enough turns to acheive a tight seal and "...how much is that?" you may ask. Two turns...maybe four turns...maybe ?? The answer comes with experience and experience is what you don't have much of, yet. This is why dope is better for you, for now.
Now, for 1" pipe you gonna need some bigger wrenches and some muscle. I'm thinkin 20" ones. They'll also be OK for the smaller pipes. Don't be too concerned about too tight. Pipe can take quite a bit of torque. You've never seen a skinny plumber.

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