phantom gas leak

[hvac4u]

we do a LOT of new construction (41 roughs next week)
apparently fulton county georgia inspects the gas line on the final. now the sheetrock is up, finished and painted, and we have a leak in the line. the guy who should have caught it before sheetrock quit and this one fell through the cracks. they cut 15 holes in the sheetrock yesterday where the joints were, (and a few other places) and could not find it.

used nitrogen, ran it up to 75 to see if they could hear it, no luck.

i gotta go out there monday. got any ideas?

[blu70devil]

Bring some matches.......problem solved!

[oil lp man]

Tell the guy who quit what happened. It'll put a smile on his face.

[Twilly]

It's been awhile but I have seen holes in fittings....elbows
and tees so don't overlook them.

Important ????? is it a slow leak or fast leak? Is it leaking in LBs or Inches?

Could a shut off be leaking thru?

[prolinehtg]

I would bet money that your using fittings that say made in china on them. Seems like every job I do has at least one leak since our supplier quit carrying ward fittings and switched over to those "made in china" fittings. I cant find anyone in town that carrys any usa made fittings. Lately what I have been doing is using wardflex and making a manifold and installing it in the mechanical room. No fittings are covered up and gas piping is speed up. Good luck finding that leak.

[41gasman]

hvac4u.
Make your self up one of these little buggers.I used a old torch head I had.Cut off the end were the flame would have come out.Put on 2' or 3'of 3/16"(ID) rubber hose with a stainless steel clamp.On the othere end of the hose put on a air chuck(like you would use to fill up a tire)This will let you introduce a little LP into the gas piping though the gage.You don't need all that much LP in there but some anyways.Go to the end of all the branches of the piping and bleed the thing out tell you get a wiff of LP.Now you go to the truck and get out your combustible gas detector.Crank that thing up and go very slowly across all the fittings.AS was said before There are a lot of fitting make in othere parts of the world that have pin holes in them from the castings.This might sound a little weird but it works very well.If you have a very slow leak and the detector only gets you close.Then you can use that spray bottle of soapy water and wait.I have had large systems that had a leak in the one pound loss over a day and a half.That I played hell finding(hours)Because a very small leak can take five or ten minutes to start makeing enough bubbles to see with the flashlite.Best of luck.I will keep eye on this post to see if you understand what I discribed makes sence to you.
Man do I feel your pain!!!
41GASMAN.

[hearthman]

Sounds like a sales pitch for CSST; one joint on this end and one joint at the other.

If the AHJ won't let you introduce LP into the system, try an ultrasonic leak detector. Only works for larger leaks. I guess you could pipe in water and look for the flood...sorry, couldn't resist. You could pipe in refrigerant but the EPA would bust you for that..
How about a smoke bomb? Oh, yeah after 9/11 they are called smoke generators...

If you use soap bubble solution, make sure it is non-corrosive or wash the hell out of it so it doesn't cause stress cracks.

Worst case, you could cut a few branches and localize the leak. Good luck!

[cem-bsee]

that is why I use Loctite on ALL threaded connections! stops leaks, prevents corrosion, prevents back- out of bolted connections, especially due to vibration.

[41gasman]

I got to say csst is some pretty cool stuff.BUT...It looks like sh!t.With the price of the tubing and the fitting it can be pretty stupid to use it in a lot of applications.As far as looks go it just looks like the kid next door did it.And with the rules on it's use with the heat treated cover plates it can get pretty pricey.BUT(theres that word again)If I am running gas pipe in a crawl on a retrofit job well your dam right that whats going into the place.Besides if a guy can't install a job in hard pipe with out having leaks all over WELL..... maybe you should see how the guy does at installing a bunch of flex ducting for you local competitor.To be honest it took me awhile to get the feel for how tight was tight enough.Probably run in the 98 to 99 percent no leaks the first time now though.Those first jobs sure were hard on me though.When you have to take half of the system apart to fix a leak.You start to learn pretty quick.Besides hard pipe maks it look like you know what your doing.Because you DO!!!!
41GASMAN

[majormickey]

I agree with hearthman. Might have to isolate branches or sections. Process of elimination. I've had some of those less than desirable jobs. Just have to tell yourself it won't be easy and give yourself alot of time, and try not to think of where you have to be next. Good luck.

[hvac4u]

41gasman, i have a very good combustible gas detector, and the meter is set so i will hook it up and look. good idea.

all fitting do say china, new construction, go figure. builder is in top 5 largest in USA, so i am sure we were not the high bidder...

thanks for the advice

[karsthuntr]

Why can't you use ref. to check for a gas leak? You can use it in a system to check for a leak and ca legally vent it. You only need a little bit and you can use nitrogen to increase the pressure. Just don't use R-410A and your air compressor...................can you say boom.

[hvac student_4063]

Originally posted by cem-bsee
that is why I use Loctite on ALL threaded connections! stops leaks, prevents corrosion, prevents back- out of bolted connections, especially due to vibration.

Yeah, Loctite makes it REAL nice for the next guy. Nothing like having to pull out the Sawzall just to change a gas valve.

[onemorearrow]

I've used peppermint scent to find the general area of the leak. Use the strong stuff from the drug store. It's about $9 per oz. Don't get it anywhere but in the pipe, or you will smell it every where.

[41gasman]

Loctite is not code because it set up hard.it it also prone to leaks over time.And if you use the locktite that is FOR pipe fitting the stuff will never let go.I have run into some retro jobs where I have crushed 1 1/4" black pipe and then and only then might the threads break loose.SO no problem then you say.Well if your lucky that day and you don't crush the pipe and it come undone all you have to worry about is the fact that there is not any threads left.Because the stuff is britel and the little tiny pieces get stuck between the male and female end and gauls the
sh!t out of the soft fitting!!Yep good idea.You a cresent wrench and a screw driver.......I R can FIX anything under the tree in the back yard!!!!
41GASMAN