capping a gas line

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I want to cap my gas line right in front of the fireplace, so that I can have the fireplace replaced. The problem is that there is no valve between the meter and the fireplace. Is it OK to just disconnect the fittings to the fireplace, let some gas leak out, then install a cap on the pipe. I certainly want to do this safely, but I cannot think of a better way. I thought of turning off the gas at the main line, but if I do that, I don't know how to turn the furnace pilot light back on. Does anyone have any better ideas? More importantly, is it safe to cap the natural gas line like the way that I described above?
Thanks, RB
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Glad I don't live close to you.
Hire a licensed plumber to do this.
--
Best regards
Han
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People do use the thumb and then screw-the-cap-on method all of the time.
My dad used to do that every year when we removed and then reinstalled the gas stoves that heated our old house.
HOWEVER, one year he didn't quite get the pilot light turned off and we suddenly had a plume of blue flame shooting up to near our 10' ceilings. Then the plastic kitchen curtains caught fire. While they were running around trying to find the outside meter valve their 11 year old son (me) suggested grabbing the hose outside of the door and squirting it out. "Too much pressure" was the response.
I went outside, got the hose and gave it a one-second squirt. I don't know if they were more relieved than pissed that I got it out that quick.
Childhood memory.
RonB
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I think that your story and the obvious inexperience of the OP makes him a potential candidate for the Darwin Awards ...
--
Best regards
Han
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I just did the reverse to hook up an NG BBQ. I pulled off the cap and installed a cutoff valve. Connection was made outside. Dont think I would do it inside without cutting off the gas.
Jimmie
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Things like this are needed to eliminate the most stupid and worthless homo sapiens born into this world. It's called survival of the fittest. It's a good thing to eliminate people like this, so they dont reproduce, but unfortunately this situation could endanger the lives of others and destroy the homes of neighbors. It's too bad that people like the OP dont post their full names and addresses so that others could contact their local fire department and law enforcement before they take the lives of others.
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On May 14, 7:22pm, snipped-for-privacy@myplace.com wrote:

Actually the OP's post probably doesn't deserve this kind of ridicule; any more than my dad did in my previous post. Those a little older will remember when shutoff valves were pretty uncommon in older homes. The thumb-then-cap trick was not uncommon, and often used by plumbers or installation men. You had to be careful. And make sure the pilot was off and a window was open.
RonB
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Hi there:
Just following up.
A couple of weeks ago, a licensed plumber replaced an elbow on the gas line for the water heater, he just disconnected the elbow, then replaced it, and even though a shutoff valve was about 3 feet before the elbow, he did not bother to shut it off, which surprised me.
I looked at the furnace insturctions last night. It turns out that the pilot will start automatically, and it is not possible to restart the furnace pilot by hand.
Armed with that information, and knowing that I can restart the pilot on the water heater, I'll just just off the main, the cap it because then I'll I know there is not any gas running.
For anyone else reading this, I was planning to cap the line from the outdoors where the fireplace bump out is. I had no intention of filling the house with gas. I don't know if that would happen in the 15-20 seconds the line would be open or not, but gas in the house is not what I want. Not only would that not smell so good, but there are other dangers too. :-)
Thanks for the advice, R
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Not sure that is a good idea, just incase the drop in gas pressure sucks the flame and air back into the line.
--
Best regards
Han
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On 5/15/2011 9:43 AM, Han wrote:

Not a problem.
It's still positive P, even if it's dropping.
It's _gauge_ pressure in inches H20; not absolute. It has to be positive pressure above atmospheric or it won't flow when you turn on a burner on the stove, for example.
If the supply valve is off, the internal pressure will drop to atmospheric but there's no way it'll go lower in a closed system (you could conceivably pull reverse on an open line that had another appliance still operating from the draft, but that wouldn't be the situation postulated w/ the main off).
--
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Yes, it is a good idea.
The flame won't flow back into the line. There's no oxygen in the line to support combustion and the openings are designed small so that this can't happen. There's now way anything would get "sucked" into the line.
Otherwise, on the first loss of pressure from the gas company the whole system would blow up.
Glad to hear it worked out for the OP. I suspected that the furnace might be auto start. Mine's got a pilot which I've had to light a few times over the years.
--
Dan Espen

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NOT TRUE.
I have LP gas in my house and when it runs out, it just runs out until the flame dies. Same as when you have a propane grill on a 20lb cylinder, or a propane torch on one of those disposible small tanks. Or for that matter, your BIC lighter. If all these things blew up from the flame getting sucked in, when they run out of gas, everything would be blowing up.
The best way to eliminate the pressure in gas pipes, is to burn off the gas on the kitchen stove or a gas fireplace, or let the water heater or furnace do it. Actually there is not that much gas in the pipes, and the flame will go out quickly, but burn off what you can, and you wont have the odor or slight risk of an explosion.
As far as the OP finally getting wise in this matter, and having an electronic ignition in his furnace, why not install a valve on this gas line while you're at it. Unscrew the pipe from the fireplace to the basement, put the valve in the basement right below that rise pipe. Be sure to still cap it when you're doing your work and the pipe is not connected. All it takes is someone to turn that valve and fill your house with gas. NEVER leave any unused gas pipe uncapped, unless you are going to connect the "appliance" immediately.
By the way, when shutting off the gas main, be sure to turn the thermostate way down, or cut the power to the furnace or that electronic igniter will keep sparking, and could burn out.
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rabacu wrote:

That will work. You can use your thumb to contain the gas - it's at ridiculously low pressure. You should be able to cap the pipe in no more than a secod or two which is about the same amount of time raw gas is dumped into your kitchen while you fiddle with a match or wait for the electronic ignighter.
Oh, it's okay to be smoking also - a cigarette is not hot enough to ignite natural gas.
When you reconnect your artifical logs or log ligher, add a shut-off valve to the piping.
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You should have a seperate valve on the fireplace and any other gas apliances. Its just smart for future problems, your install was done cheaply and isnt to code. Just turn off the main and learn to light the furnace pilot and do it right, what if the chinese cap you get has a bad thread, what if the pipe thread is damaged, what are you going to do , start running to the main shutoff just to find you need a big wrench you dont have handy? Sure you can do it your way, nothing ever goes wrong, maybe duct tape can stop the gas if you have problems.
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On Sat, 14 May 2011 05:00:38 -0700 (PDT), ransley

I think he has proven that high IQ doesn't run in his family.
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rabacu wrote:

Given this information, you should call a professional to do the work for you.
Jon
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I have to be honest here. A knowledgeable person could do what you want to do, but I'd say you definitely should NOT attempt it.
If you don't know how to light the pilot of your furnace, you probably don't have the ability to make a fast and secure capping of the pipe. Get a plumber or gas fitter and have a valve installed the way it should be done by code.
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I could just see him stripping a thread, then choking from gas in the small space and running, then from lack of knowledge of tools failing to close the gas main, have a heart attack, and cant move, then someone ringing the doorbell later blows him up alive. Ive capped pipes, but it made me nervous.
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On Sat, 14 May 2011 08:27:53 -0700 (PDT), ransley

And dont forget the pilot light is still burning in the furnace, and possibly the water heater too.....
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I looked at the furnace insturctions last night. It turns out that the pilot starts automatically, and it is not possible to restart by hand. Armed with that information, and knowing that I can restart the pilot on the water heater, I'll just just off the main, the cap it when I know there is not any gas running. For anyone else reading this, I was planning to cap the line from the outdoors where the fireplace bump out is. I had no intention of filling the house with gas. Not only would that not smell so good, but there are other dangers too. :-)
Thanks for the advice, R
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