How to cap a live natural gas line


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Old 10-30-17, 07:20 PM
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How to cap a live natural gas line

Hi all, I've done plenty of work with a pipe wrench, but only once before on a live gas line (and that was more simple than even this). The attached photo shows a Threaded Tee that feeds a bunch of out-of-use piping. I *need* to kill that out-of-use piping, and so the object here is to cap this useless junction at either of the two locations circled in yellow.

I've got my recip saw with bimetal blade; got my pipe wrenches; got my pipe dope; got multiple plugs (just in case).

Obviously, Step 1 will be to shut off the gas at my meter. My question to all of you: could you please coach me on the appropriate subsequent steps in order to get this done? Seems pretty simple to me, but I want to make sure I'm not missing something. We are dealing with live gas, after all. Thanks in advance!
 
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Old 10-30-17, 07:59 PM
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Why can't you follow that out of use piping to another spot or to the terminal and start removal from there? Are there no unions along the line? How about more pics showing where that line goes?

The first thing I would want to do after turning off the gas at the meter is to relieve the gas pressure in the line and evacuate the gas from the line. I would not want to open that plug, especially if you're in an enclosed space like a cellar. Again, where do those line terminate? Once that is done I think a saws-all would do the job.
 
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Old 10-30-17, 08:14 PM
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Turn off gas.
Take out thet plug
Cut top yellow circle area
Turn out tee. ( hopefully nipple wont come out) Then cap
If nipple comes out then put in new nipple and cap.

dont cut circle on right side of your pic.
 
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Old 11-01-17, 07:25 AM
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Thinking about relieving gas pressure and evacuating the pipe... Along with the fact that natural gas is buoyant... Have you ever heard of or seen someone using a shop vac to kinda suck out the gas from a pipe after removing the first plug?

Turn off gas.
Take out thet plug
Cut top yellow circle area
Turn out tee. ( hopefully nipple wont come out) Then cap
 
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Old 11-01-17, 08:07 AM
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have you ever heard of or seen someone using a shop vac to kinda suck out the gas from a pipe after removing the first plug?
No. .
 
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Old 11-01-17, 08:12 AM
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Originally Posted by lawrosa
No. .
Good idea or bad idea in your opinion?
 
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Old 11-01-17, 08:16 AM
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How do you relieve pressure and evacuate gas from the line without taking out that plug?
That white fitting above the Tee sends the pipe to a location where the pipe runs along the wall without any clearance; like, right up against the wall. That wall run is about 30 feet long, with one offshoot going up into an interior wall. I've identified the location shown in the photo that I posted as the best place to add a cap/plug. That location is very close to where service enters the house, so killing it there also prevents gas from sitting in unused pipes inside my walls and ceilings.

Why can't you follow that out of use piping to another spot or to the terminal and start removal from there? Are there no unions along the line? How about more pics showing where that line goes?

The first thing I would want to do after turning off the gas at the meter is to relieve the gas pressure in the line and evacuate the gas from the line. I would not want to open that plug, especially if you're in an enclosed space like a cellar.
 
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Old 11-01-17, 08:22 AM
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How do you relieve pressure and evacuate gas from the line without taking out that plug?

Gas is less then 1/2 psi.. Why dont you want to remove the plug? Why do you think you need to relive pressure?


I suggested what you should do.. No worries about gas sitting in pipes... Im a plumber 30+ years..


But if you feel better using a vacuum go ahead.. No reason to ask here if that's what you want to do..
 
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Old 11-01-17, 08:31 AM
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What Mike (Lawrosa) is saying may be perfectly alright, but I don't feel comfortable with about 30 feet of pressurized gas in an enclosed area and just opening that plug.

I also don't quite follow what you're saying. The gas line that you want to eliminate, (at least in terms of holding gas, if not actual removal). Can't you open that line at it's termination and evacuate the trapped gas at that point? Is the termination buried in the wall? If so how can you be sure that is the end of the pipe and if it's capped or plugged?

Mike, what am I missing here?
 
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Old 11-01-17, 08:51 AM
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If it was a 100# it might be a problem, it's only a half pound.

Natural gas is lighter than air, the little amount that is in there just dissipates.

You try sucking it into something you'll probably blow that up.
 
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Old 11-01-17, 08:58 AM
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If the white pipe is just being terminated, after its cut just leave it. Take out the 30 ft along the wall, but just leave the pipe open..

The other side of the tee I take it needs to be capped or plugged so you can turn gas back on to run the appliances on that line...
 
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Old 11-01-17, 08:59 AM
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Got it! Thanks.

To the OP...Just remove that plug and cut the pipe.
 
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Old 11-02-17, 10:36 AM
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Thanks to everyone for your comments. I realize now I should have included more information originally in order to give you a better idea of what I'm dealing with. Better late than never? Here are 4 more photos with descriptions. Before I being, let me just point out that we have just three natural gas appliances; 1) boiler 2) water heater and 3) kitchen stove.

Photo A:
Arrow 1 shows were service comes into the cellar from the gas meter (outside).
Arrow 2 shows the first branch which leads only to the water heater and the kitchen stove.
Arrow 3 shows the second branch which leads only to the boiler.
Arrow 4 is the area shown in my original photo, which shows the Tee in question and the third branch which does not service anything, but which is still live.
Name:  img_A.jpg
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Photo B:
A closer view of the area in the original photo;
Arrow 1 is the branch that leads nowhere.
Arrow 2 is the branch that serves the boiler.
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Photo C:
Just to show you the length of pipe that's in the cellar; the area shown in my original photo has a yellow circle around it (in the distance, lower right corner of Photo C); the yellow arrow in this photo shows where that line takes a 90-degree turn. It's around 20 feet (give or take) between the Tee that I want to cap and this elbow. Note that from this elbow, the line continues in the cellar for another ~15 feet before turning vertical and rising for another ~20 feet.
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Photo D:
This photo just shows another Tee that exists a few feet before the elbow in Photo C; from this Tee, the line goes vertical up into the center wall of the house, about 20 feet, before ultimately terminating in the center of my living room ceiling (capped).
Name:  img_D.jpg
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Size:  91.0 KB
 
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Old 11-18-17, 01:24 PM
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What happens to the gas that's still in the pipe??

The first photo shows my living room ceiling, which is on the 2nd floor of an old victorian multi-family house. I suppose there was once a pendant-style electrical fixture right in the middle there where the wires are sticking out from a non-modern junction box.


The next photo is a close-up of that area, where you can see a hex cap which is the termination point of a natural gas line. Don't ask me what it's doing there. Two separate plumbers have confirmed that this gas line is live.


The third photo shows the Tee joint in the basement near the gas meter that feeds that entire line, which is not used by any appliance. Again - that entire line is literally useless.


I'd like to remove that Tee joint and cap/plug the line right there in the basement. But if I do that, then I'm left with a bunch of gas pipe running through my walls and ceilings that's full of natural gas. So my question: what happens to that gas? is there a safe way to evacuate it to the outside of the home?

Thanks in advance for your advice!
 
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Old 11-18-17, 01:36 PM
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Threads merged..... did you forget you already started a thread or are you looking for different answers ?

Once the gas main is shut off..... NOTHING will come out of that pipe when you uncap it. Possibly the smell of gas..... that's it. No need to suck it out or send it anywhere.
 
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Old 11-18-17, 01:50 PM
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Questions that have been sufficiently answered by a competent professional ought to be closed, imo.

Yes, sucking up residual natural gas into a shop vac (motor with sparking brushes) is not what I would call a good idea. Once you shut off your gas at the meter, your pilot light will go out when there is no more gas pressure. The remaining gas is not going to come pouring out like water when you remove the plug. As long as you don't put a match on the end of the pipe, nothing will happen.

Bit of advice to the op... listen to the advice you have already been given.
 
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Old 11-18-17, 03:21 PM
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The next photo is a close-up of that area, where you can see a hex cap which is the termination point of a natural gas line. Don't ask me what it's doing there. Two separate plumbers have confirmed that this gas line is live.
Back before electrical wiring, houses were set up with gas lighting. Many of the fixtures seem to have been fed by 1/4" steel pipe, which in most cases have been capped and/or disconnected. I just renovated a 1920's house in Philadelphia that has the remnants of old gas lighting.
 
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Old 11-18-17, 07:59 PM
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Thanks again to everyone for your comment and advice.

Today, 03:36 PM #15 (permalink)
PJmax
Threads merged..... did you forget you already started a thread or are you looking for different answers ?
Did not forget, though I admit I did not realize that what I meant to be a new thread would merge with the previous one. I felt that today's question qualified as a new thread; I am concerned specifically about that hex cap in my living room ceiling, because it comes down beyond the surface of the ceiling and my goal is to essentially disappear that whole mess. This means that I'm going to remove the ~6-inch piece of pipe that's sticking down from the ceiling, which will leave that end of the pipe open ended inside my ceiling. My concern is that the gas that's currently sitting in that pipe between the basement and my living room ceiling will just seep into the void inside my ceiling (between floors). I suppose that the volume of gas that will potentially seep out is small enough that it shouldn't be a concern, but I guess that's really the primary question here.

Today 03:50 PM
XSleeper Questions that have been sufficiently answered by a competent professional ought to be closed, imo.

Bit of advice to the op... listen to the advice you have already been given.
I apologize for the apparent redundancy. Did not mean to discount the advice that was already given. As described above, today's question was a related to the original, but sufficiently different to warrant an additional question, in my opinion. I'm happy to work with electrical and plumbing, but working with gas is new for new for me and I'm just trying to think this out as thoroughly as possible before executing.

Zorfdt
I just renovated a 1920's house in Philadelphia that has the remnants of old gas lighting.
This place was built in 1900 according to the books. As far as apparently random gas terminations go, I have two... this one in the living room ceiling, and one poking out of a wall in the kitchen.
 
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Old 11-18-17, 09:00 PM
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Cut the tee as I explained below. After thats done if it makes you feel better take a compresser and blow the line out from the hex cap down to the basement..

Then remove whatever of the old piping you see fit...

Done....

Your worrying too much...

Call in a plumber if your fearful of gas... No need to lose sleep over this project...


Turn off gas.
Take out thet plug
Cut top yellow circle area
Turn out tee. ( hopefully nipple wont come out) Then cap
If nipple comes out then put in new nipple and cap.

dont cut circle on right side of your pic.
 
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Old 11-19-17, 09:17 AM
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Mike, thanks again for everything. I appreciate it.

 
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Old 11-19-17, 09:32 AM
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Looks good.............
 
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Old 11-19-17, 10:58 AM
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Feels good!



 
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Old 11-19-17, 03:27 PM
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Did you verify the plug/cap you put on the "T" is not leaking? If not you might want to check it to be sure.
 
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Old 11-20-17, 09:07 AM
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Originally Posted by Ron53
Did you verify the plug/cap you put on the "T" is not leaking? If not you might want to check it to be sure.
Checked it 6 times! Thanks for the look out.
 
 

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