repair natural gas pipe leak?

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I smell a small natural gas leak in my crawl space. I think it's been that way for several years. Previously I had called the utility company to check. The guy refused to go into the crawl space. Instead, he looked at the gas meter for a few minutes and decided that there is no leak, and left.
Today I went into the crawl space, and again, when I'm near a certain section of the gas pipe I smell gas. So I'm pretty sure there is a leak. The pipes are metal rigid pipe, with a little bit of rust.
I'm thinking DIY repair, but the pipes are rigid and screwed together. In order to remove one section of pipe, I'd have to turn it which would loosen it on one end and tighten it on the other end. Are they designed to be loosen this way, or would I strip the thread on the tighter end? If I can losen the pipe, then I think adding a piece of pipe tape to the thread and screwing it back may do the trick, except that the other end may now start to leak after being overtightened and then loosen again.
If I get a contractor to fix this, what are they most likely to do to fix this?
The house is 20 years old and the gas pipes probably are as well.
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james wrote:

That's totally unacceptable; I'd report that to the utility company. At least here they're responsible to at least determine unequivocally the presence/absence of leaks although it's you nickel to repair anything on your side of the meter.

This is too potentially dangerous a situation to leave unattended...

No, and no but you'll never get a joint apart that way, either.

Indeed....
First, have to determine where, _precisely_ the leak is--do you even know for certain it is the joint itself and not a pinhole failure?
Depends on how far it is back to a union and where the leak is identified to be and what the root cause is. If they determine it is the joint itself and it's a long way to a union likely they'll cut the pipe and insert a union. If it's not too far away they'll take it back to that point and reassemble and/or replace depending on the conditions they find.
--
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I would definitely fix such a leak. However, it is not an imminent emergency if the crawl space is ventilated. Natural gas only becomes explosive when the concentration in air is above 4-5% (and below 15-17%), and a small leak in a ventilated crawl space will never build up that much.

This can be an acceptable method to check for a leak but it takes longer than a few minutes. It requires that all gas appliances be off. If any of them use a standing pilot, you have to close the shut off valve to that appliance and relight the pilot when finished.
Then you use a piece of tape and align one edge of the tape exactly along the pointer dial on the least significant dial (the one that turns fastest). Come back in a couple hours and see if the pointer has moved. If it hasn't, you don't have a leak.

Just an FYI, the plumbing codes I am familiar with only allow unions at accessible locations, such as the gas meter and at an appliance. So in a crawl space the proper connection to use is a left/right coupling, which is a nipple/coupling combination which is left-hand threaded. That way you can rotate the coupling in one direction and simultaneously tighten (or loosen) both ends.
Cheers, Wayne
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well most utility companys who find a leak on the homeowners side do one thing, turn off and red tag meter and home till a registered plumber fixes it and pressure tests the entire homes gas lines.before gas will be turned back on. they might require checking the underground line too......
now that doesnt sound too bad but natural gas is at most a couple PSI.
But the required pressure test is 75 pounds. This high pressure finds leaks that never leaked before it literally creates leaks.
Around here with rusty pipes the plumber will mosty likely want to replace ALL the gas lines. Cant say I blame them just one tiny bit of rust allows a leak at 75 pounds and they must start all over, at their expense......
I would go find the leak with soapy water before proceeding.......
Once you know where it is it might be repairable, if the lines are rusty you will need them replaced
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snipped-for-privacy@aol.com wrote:

They required the test at 15 psi here in Seattle.
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Yep, thats what they do. Wife called the gas company about smelling gas in the garage. She didnt want to wake me up at 10AM given Im a shift worker. No hot water for 10 days, $400 dollar plumber bill to tighten the flare coupling on the water heater.
Jimmie
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Wayne Whitney wrote:

...
Well, we don't know much (as in anything) about that here, do we? And, if it's been leaking for years, there's no telling for sure that it won't worsen quickly, either, depending on what the root cause might be.
You can make any judgment you wish about the severity of the situation; I'm not about to make light of any such incident from afar...
--
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On Thu, 1 Jul 2010 10:22:01 -0700, james wrote:

Before you do anything else, take soapy water and find the leak if there is one, it may be in a place that isn't hard to fix. check all the fittings and pipe as well, it is unlikely the leak is in the pipe but not impossible. The pipes actually look good for 20 years. The first place to look for a suspected leak would be where the pipe comes through the foundation, corrosion will be worse there than anywhere else.
basilisk
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james wrote:

Hi, Don't mess with it/ Just call your gas co. They'll be more than happy to fix it for their own interest.
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Tony Hwang wrote:

If it's on the house side of the meter, where I live it's the homeowner's responsibility.
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Tony Hwang wrote:

No they won't. They'll turn off the gas until the owner certifies the leak has been fixed.
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james wrote:

You crawl under there with a spray bottle of soapy water and spray the joints and look for leaks. If you can't find the leak (if there is a leak) you cap all the ends disconnect from the meeter and do a pressure test and once again with more air pressure on the lines, you crawl under the house with the spray bottle of soapy water. If it's leaking at a joint then you have to decide if you want to start unscrewing the pipes or cut one out and put in a union. It's a lot fun. Make sure the pipes are hung properly so they don't sag or put stress on the joints. Beware, if the gas company does find a leak they are apt to leave with your gas meter in the back of their truck.
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Thats the way they work here in LA as well... and they make a big stink over re-inspection before reinstallation of the meter.
Oh, and of course, all at your expense, and on their 'schedule'.
Erik
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Well, the first thing thing that comes to mind is that living in a house with a suspected gas leak for "several years" is, well, stupid, but apparently you survived long enough to post your question.
If it were me, I would have *insisted* that the utility company do a proper check with a sniffer to determine if there was a leak or not. If I were you, I would *insist* upon that before I touched a pipe or called a contractor.
The next question is this: Is there a shutoff to this section of pipe or does it come directly from the meter? If there is no shutoff, and your gas meter is anything like mine, you're going to need to get the utility company involved anyway. Unless you plan to fix the pipe "live" (a very stupid idea) once you shut the gas off at the meter, you'll need to call your utility company to have them turn it back on. At least, I do. The meter locks itself out and the utility company has the tools to turn it back on.
Finally, in most cases, you'll need to go to find a union to remove any section of pipe. All junctions are going to be threaded the same way, so you can't just unscrew one end have the other end unscrew also. Another option is to cut the section and insert a union.
In any case, you really should get the utility company out there, if for no other reason than to get some decent service for all the money you've given them over the years.
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james wrote:

YOU have to find the leak. Or pay someone to do it. Couple of points:
1. It may not BE a leak. While Mercaptan has a distinctive smell, the odor may be coming from something else entirely. Did one of the previous owners of the house disappear under mysterious circumstances?
2. Use some cardboard or similar to block off as much air-flow as possible thereby increasing the concnetration of gas under the house. Does the intensity of the oder increase?
3. When you do find the leak, remember natural gas pressure is measured in OUNCES/sq in (about four ounces). It doesn't take much to stop such pressure: Heck, a Band-Aid would do it.
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-snip-

I have a spot in my detached garage that reeks of some 'mercaptan'y smell. It has for 25 years. There is no natural gas within 1/2 mile. My propane tank is 100feet away on the opposite side of my house- which is 50 feet from the other side of the garage.
I've torn everything out to the inside of the T-1-11 siding- smell is gone for a day, or a week, or a month-- then I smell it again. I'm guessing the previous owner spilled something there-- or it is right in the concrete.

Hmmm--- I did find a prosthetic leg in the attic. . . maybe the old leg is beckoning from below the garage?
Jim
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Call the local fire marshall and ask him for a residential inspection. He can use this as a training exercise for new recruits.
He should really know how the local utilities operate and function.
*
_Fire Marshall Bill in National Fire Safety Week Jim Carrey_

http://www.youtube.com/watch?v=PlLPogmB8M8

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Gas is low pressure so epoxy should fix it depending on the leak, use soapy water to find it.
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On Thu, 1 Jul 2010 19:35:36 -0700 (PDT), ransley

Use soapy water to find it. fixing a loose connection mid-stream requires a pipe union - the difficult part is removing the original pipe without causing a spark. A cut-off wheel is NOT the answer - a hacksaw can cause a spark, but if you flow water over the cut it is extremely unlikely. Spin out both ends, buy 2 peices half the length and a pipe inion, or rethread the cut ends if you have the equipment available. Use teflon pipe dope on the joints - NOT TEFLON TAPE.. The proper union is usually referred to as a "ground joint union" which has accurately machined or ground taper that does not require pipe dope or gaskets. They are legal if accessible, although code calls for them only at the meter and at consuming devices.
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Shut the gas off first. The gas company will weld on the pipes if the gas is shut off.
I'd not use a cut off wheel in a crawlspace anyway, but I'd use a hacksaw or reciprocating saw.
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