Gas pipe tightening question from a newbie

At risk of sounding like a total novice (which I am)....I would very much appreciate guidance regarding tightening gas pipe and connections:

Specifically........if a run of gas pipe is put together, in this case roughly 65 feet total, with about 15 fittings along the way, and the finished piping shows leaks in one or more joints once the line is pressurized, how is tightening best accomplished?

Since rotating a pipe with a wrench to tighten it in a fitting at one end simultaneously causes the other end of the pipe to now rotate out of the joint at the other end, perhaps starting a leak there, it seems like there is no obvious way to tighten a leaking joint without risking another leak.

The alternative, taking the whole thing apart down to the leaking joint and then rebuilding the entire remaining run also does not seem a like a smart or efficient method.

It is tempting to "overtighten" each joint initially, on the theory that backing off on one connection at a leaking end will still keep the opposite end of the pipe firmly connected after rotating the pipe. This may be the correct method, but I have not seen or heard this approach suggested.

Most of the couplings, elbows, and unions I have seen appear to accept at least a couple full (360 degree rotations) before they snug up.

I thought about putting unions all over the place so that each segment could be independently tightened. I have not seen professionals use this approach, so I am guessing this is not a great solution.....

Thanks in advance for any ideas. I am totally clueless..

Smarty (should be called not so Smarty!)

Reply to
Smarty
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Frankly, I use a few unions. I think the pros don't do this for 2 reasons, experience has taught them how tight everything has to be, and cost, unions cost $ couplers cost cents. A third reason is that they use liberal amounts of dope, a forth would be tools, most people don't own a 4' pipe wrench let alone 2 nice light aluminum ones.

Reply to
Eric in North TX

Since you are a newbie don't be surprised if you have to take it apart and start over. At least your pipe is all threaded and correctly sized.

Tightening the pipe is not the solution to avoiding or correcting leaks. You should be using pipe tape which is wrapped aroung the thread on the male end . It is this tape which prevents the pipe from leaking not tightening it more or less.

So if you use the tape correctly you will have far fewer worries since the tape that does the job not the threads on the pipe. You cant be too safe when installing a gas line so be sure to double check each joint before leaving the gas on.

Reply to
Lawrence

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.

Reply to
Toller

I'm just a wonderin' why so many joints in only 65'?

Reply to
Steve Barker LT

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

Reply to
Wayne Whitney

Thanks Wayne,

Never heard of a 'left/right coupling.......What is it?

Smarty

Reply to
Smarty

Lots of pipe dope / tape and more unions seems like a good way for me to proceed.

Reply to
Smarty

Thanks Lawrence,

Now I wonder if tape is a better choice than the goopy joint pipe dope I was thinking of using?????

Smarty

Reply to
Smarty

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

Reply to
Smarty

Wayne,

I wonder if unions are not allowed because they have some greater risk of failure?????

Smarty

Reply to
Smarty

I watched the gas companys contractors install gas pipe for a furnace and watet heater. They used pipe dope and overtightened everything. They really reefed on the wrench as they tightened each joint.

You could pressure test each section as you go. Pressurize with air, and check for leaks with soap water.

Bob

Reply to
Bob F

May be time for me to invest in an air compressor. Wonder if bubble / leak testing can be reliably accomplished with a cheap pump of some type?

Reply to
Smarty

Thanks very much Bob. I probably should have asked this question first:

How much tightening is normally applied for doing gas pipe? My wrenches are, at most, 12 or 14 inches long. And the pipe is mostly 1", with a few feet of

3/4 inch at the appliance (generator). Do I torque things down to the point where the male threads bottom in the fittings? I understand that dope / tape does the sealing job, but I have not a clue as to what the correct way is to tighten gas pipe joints. Your reply sounds like I maybe should be using a longer wrench and a lot of muscle.

Smarty

Reply to
Smarty

More text inserted.

Reply to
Stormin Mormon

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

Reply to
Don Young

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

Reply to
James "Cubby" Culbertson

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....

Reply to
cornytheclown

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

Reply to
bill allemann

CY-

I don't think this is correct...the joint should be leak free way before the male thread bottoms in the fitting

I do agree with your other suggestions...12 to 14" wrenches are a little smal for 3/4 & 1" joints

cheers Bob

Reply to
BobK207

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