Gas Line Won't Hold Pressure, But Can't Find Gas Pipe

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MikeGA

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I'm hoping some intelligent, experienced people can help me out here. Long time reader, first time poster.

I recently repiped all the gas lines in my house with black steel. While I am not a professional plumber by trade my father is a retired master HVAC technician and master plumber for 40 years, so with that, I have been working with gas black pipe and HVAC systems for 15 years.

The main is 1 1/4", then branches off to 3/4" and 1/2", depending on the appliance. I have been using RectorSeal T Plus 2 pipe dope for all of my jobs, including this one.

I did an air pressure test and found apparently there is a leak. I pump the system with 15 psi, then it loses about 1 psi every 15 minutes or so, then stabilizes at 10 psi.

Ive used Oatey leak detector, Windex, and soapy water on ALL joints and absolutely no bubbles. I'm completely baffled here.

My question to the group here is are there any high-tech tools or any other testing tools that I can use to identify the leak in any of the joints. Has this ever happened to anyone before? If so help me out here, I really don't want to remove the entire system and repipe it, now that the ductwork is up it's extremely difficult.
 

WorthFlorida

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I do not know of any magic but the basics? Are all ends capped off for the pressure test or any of it connected to an appliance? Sure your pressure gauge or fitting is not leaking? At the branch or tee, can you install a valve to close off each branch to narrow it down?
 

MikeGA

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I'm attaching the diagram. I have 4 appliances connected so far; 2 furances, 1 tankless hot water heater, 1 pool heater (which has been unused for 12 years, so i do not know the condition). As you can see from the pic, I have the pressure test at the main and then I have shut-off valves to everything. Has anyone had any experience with the gas valve itself not being able to support the PSI? Each gas valve is shut off. I think my next step will be to remove each shut off valve and replace them with caps.

Additional thoughts here?
 

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MikeGA

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call a professional leak locator. They have spcciallized equipment to find even the smallest leak.
Will the professional leak detectors be able to leak air or gas only? I thought the specialized equipment was only for detecting gas.
 

Michael Young

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I have NEVER TRIED THIS, but I'm hoping some hvac person will chime in.

They do make refrigerant leak detector that is visible using a black light. would it be possible to use refrigerator leak detector and a black light to find micro-leaks in gas piping?
 

MikeGA

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I have NEVER TRIED THIS, but I'm hoping some hvac person will chime in.

They do make refrigerant leak detector that is visible using a black light. would it be possible to use refrigerator leak detector and a black light to find micro-leaks in gas piping?
Can you point me to the product you're referring to? Ive used refrigerant leak detectors in the past and they work great because they're detecting specific chemicals.
 

hj

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You would have to fill the pipe with it before it would leak out. Leak detectors fill the pipe with their own gas,possibly helium, and then use their detectors to find it.
 

Reach4

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Where in your diagram do you inject air and measure air pressure?
 

Mliu

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Why do you have 3-way ball valve symbols at every branch junction? Are we to assume those are simply tees thave have been assigned the wrong symbol in your diagram?
 

MikeGA

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I purchased an ultrasonic leak detector and snoop. I will also be removing all the shut off valves and replacing them with caps. I will now put in 30 psi and use both the ultrasonic and snoop to try to pinpoint the leak. My question is though...if gas only comes in at 1/2 psi, wouldnt it be natural to get leaks at pumping it to 30psi. Ill keep everyone posted.
 

MikeGA

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Why do you have 3-way ball valve symbols at every branch junction? Are we to assume those are simply tees thave have been assigned the wrong symbol in your diagram?
Yes, these are T's...sorry, not using the right icon. I will post the picture later today, but the psi valve is located right on the main. Does it make a difference where the psi valve is located? It shouldnt make a difference.
 

MikeGA

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Where in your diagram do you inject air and measure air pressure?
I will take a picture later today, but the air pressure tester is located on the main before it branches out. Its right after the meter, the meter will be placed on the outside now. Also, I purchased a new 100psi reader, I was using a 15 psi reader...not sure if it'll make a difference, but Im going to pump it with more air and continue the test.
 

MikeGA

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If if it doesn't leak at 6" w.c., it will NOT leak at 30 psi.
Thats my issue...Ive gone through every SINGLE JOINT and have no leaks at 15psi. I stated on a previous reply...I purchased an ultrasonic leak detector and snoop. I will remove all shut-off valves and cap them instead. At least this approach will help me go through the process of elimination...Im wondering if the shut-off ball valves cant hold the 15psi, but even then...there are no leaks at the shut off valves.
 

hj

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The vaalves are usually rated for 150 psi, so they should not be the problem, but if they do not have plugs in the outlets, there is a very small chance that the pressure is leaking through them. Use kid's liquid bubbles and cover the fittings with it, because you could have a bad one.
 

MikeGA

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Thank you all for your help! I went through the process of elimination and the first thing I eliminated was the air valve that I was using and replaced it with a proflo 100 psi. That was the issue! it's now holding steady;I have it at 20 psi for 30 minutes with zero drop, I'm hoping it'll stay this way
 

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Reach4

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I went through the process of elimination and the first thing I eliminated was the air valve that I was using and replaced it with a proflo 100 psi.
If that is a Schrader valve, you might have been able to contain things with a valve cap.
 
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