1/2 PSI Drop - Gas Line

[DTAZ]

I am new to the forum. I am plumbing a gas line in black iron and have the system under 15 psi test pressure. The run consists of about 18 ft of 1 inch with an 8 ft branch of 1/2". The system has lost just under 1/2 psi over a 48 hour period. If anyone has suggestions for detecting a leak of that size, I would appreciate it. Thank you.

 

[Reach4]

They sell leak detector bubble solution made for the purpose.
Oatey 45801 Hercules Mega Bubble Leak Detector is one example.

Your leak may be big enough that you could use children's bubble solution from the dollar store.

 

[Sponsor]

 

[DTAZ]

They sell leak detector bubble solution made for the purpose.
Oatey 45801 Hercules Mega Bubble Leak Detector is one example.

Your leak may be big enough that you could use children's bubble solution from the dollar store.

Is the Oatey 45801 substantially different than the Oatey All Purpose Leak Detector? I have used that and have not found the leak.

 

[Reach4]

Is the Oatey 45801 substantially different than the Oatey All Purpose Leak Detector? I have used that and have not found the leak.

I doubt it is substantially different.

Has the pressure continued to drop? Was the pipe hot initially and cooled?
Don't forget to check around the gauge.

 

[DTAZ]

I doubt it is substantially different.

Has the pressure continued to drop? Was the pipe hot initially and cooled?
Don't forget to check around the gauge.

Thanks for the reply.
The pressure has continued to drop. It's down a bit less than 1 psi in 4 days. I did check around the gauge where it mates with the fitting and also the schrader valve. No bubbles there. My suspicion is that the "foam" that would be created by such a slow leak might be indistinguishable from the foam created by applying the leak detector fluid. I did initially have a leak at one of my unions that was difficult to track down. So, I tested the system at 100psi with an appropriate gauge, located that leak, and then needle held steady at 100 psi for a few hours. I found no other leaks at 100 psi with the detector fluid. I would also note that the increments are so large on the 200 psi gauge that I can't imagine you would see the drop I am registering on the 15 psi gauge. Alternately, I wonder if it could be leaking inside the housing of the gauge itself... Suggestions?

 

[Reach4]

I wonder if you could apply the solution with an eye dropper to avoid putting foam on the joint during application.

 

[Dj2]

An addition to your gas line ought to be permitted, performed by a lic plumber and inspected by a bldg inspector.

At this point, I would retract, re-do the addition. What did you use as a sealant at the joints and fittings? There is a chance that your gauge is not true, defective or leaky, but I think that the leak is in one or more joints.

Please get a plumber, adding gas lines is not a DIY project.

 

[DTAZ]

An addition to your gas line ought to be permitted, performed by a lic plumber and inspected by a bldg inspector.

At this point, I would retract, re-do the addition. What did you use as a sealant at the joints and fittings? There is a chance that your gauge is not true, defective or leaky, but I think that the leak is in one or more joints.

Please get a plumber, adding gas lines is not a DIY project.

Ahh, the job is permitted and I have run many gas lines. I had a former life working for a contractor. Assuming will get you into trouble. Conversely, I am not assuming, and have asked the questions because I am well aware that there are things that I do not know. I have never had to find a leak this small and have been prepared to disassemble and reassemble the work. I just want to know if there is something I am missing. Yes most people should not DIY - however, some people can. If you want to come to Tucson and do the work I want at the standard that I demand for the price I charge then you are welcome to.

 

[DTAZ]

I wonder if you could apply the solution with an eye dropper to avoid putting foam on the joint during application.

Thanks, I'm buying a new gauge and the Cal-Blue. If that does not cure the problem I'll redo the work. I appreciate your help.

 

[Rmgolob]

Curious...
Outcome?

 

[DTAZ]

Curious...
Outcome?

I did one last systematic, connection by connection check to no avail and then I disassembled the entire system and put it back together. I ended up with the same result - 1/2 +/- psi loss per day. Already having ordered the Cal-Blue, I gave the project a rest for a week. The Cal-Blue did the trick. My leak was a pinhole in a 1/2" coupling. The Cal-Blue is thick enough and clings well enough that the leak became evident in about 15 minutes. A 3/4" mound of bubbles ranging in size from 1/32 - 1/4". Any less time and it was hard to distinguish from foam created by application. I was either missing the spot with the regular Oatey leak detector or it was running or drying off too quickly to reveal the leak - not sure which. As well, a 1/2 psi per day leak twice in a row suggested that it might not be a threaded connection so I was more careful to apply detector fluid to the entire surface of fittings. I'll be changing out the coupling later today. BTW- since I'll have assembled the pipe twice, I'll probably use a combo of dope over yellow tape. Luckily the coupling is near the end of my run. Hopefully no other leaks though I've looked at every connection carefully enough that I am hopeful.

 

[DTAZ]

I wonder if you could apply the solution with an eye dropper to avoid putting foam on the joint during application.

They make Cal-Blue look good in this video. I think you would want to find a way to apply without making suds.

The Cal-Blue was good advice. Thank you. See my reply below. Bad coupling with a pinhole.

 

[hj]

Kid's bubble solution will do the same thing. It contains glycerin so it clings to the joint and creates a "praying mantis egg chain" over time. BUT, you have to spray it on the leak, which may not happen if the leak is in a fitting rather than a joint.

 

[DTAZ]

Curious...
Outcome?

Holding 15 psi for 2 days. Done.

 

[DTAZ]

Kid's bubble solution will do the same thing. It contains glycerin so it clings to the joint and creates a "praying mantis egg chain" over time. BUT, you have to spray it on the leak, which may not happen if the leak is in a fitting rather than a joint.

Yeah, I think I was either missing the hole in the fitting or it was not well positioned enough for me to see it. Also, it took a long time for bubbles to form. Not an instant Lawrence Welk bubble shower with such a tiny hole.