Small gas leak?

Question

I had a gas leak in my back yard. I called the gas co and they pulled my meter until I fix the leak. So I fixed it myself by changing an old pipe. This fixed the big leak but when I put the gauge tester (I set it on 4psi) to see if it will hold the pressure, the gauge went down to 2psi in 7 hours. So I try to look for this small leak with a bubble leak finder but the leak is to small that I cant find it. What can I do so the inspector passes the inpection to get the meter back?

Answer 1

it's possible (and likely) that the leak is actually in the guage or fitting you are using to test with.  4psi is hardly a good test.  bring it up to 30 or 40 psi (your new pipe should easily be able to handle it) and see if you get any bubbles that way.  if there is a leak you should see your pressure going down much faster with more pressure in the pipe.

Answer 2

(1) disconnect all gas fired appliances and cap them off.  (2) Pressurize all piping to 40 psi and use a childs blow bubble solution to check for leaks... and soap the gauge and "ALL" fittings...    (3)  If you still can't find the leak  ...repressure the pipe and coat all the pipe to see if you have a pin/sand hole in a pipe or nipple, union, tee, elbow, plug, valve.If you still .can[t find it ....then it is probably in your appliances,,water heater, furnace, range  etc...

Answer 3

during an inspection the uniform building code here requires 10lbs for 15 minutes <if my memory serves me correctly>  we are required to cap off all outlets during a test to pass.

generally for your situation the homeowner called us out to perform just this task.

finding a gas leak in a back yard is nearly impossible other than dead grass, because you need to locate and test "EVERY" joint which can be underground.

Answer 4

First let me quote from the national gas code for testing a gas line.Section 4.1.4 Test pressure-B-The test pressure to be used shall be no less than  1 1/2 times the proposed maximum working pressure,but not less than 3 psig.To find the leak higher pressures are not required as others have sugested.I have found hundreds of leaks with 9.5" in a water column [less than 1/2 psig] What you are describing is not a leak that is too small to find.Soap everything even things that you don't think would be a problem.Sometimes higher pressures will blow the bubbles away from the leak and it will be hard to find them.Check everything on your guage tester,many times I have found leaks at the test guage.Turn all gas valves off when testing many appliances have small leaks.Some leaks are very difficult to find but keep checking and good luck.

Answer 5

You don't have to unhook all the appliances but you should shut off the gas valve for each appliance. If you plan to use a higher pressure. pressures over even 10 psi can damage some control parts. depending on where you live the pressure test may be as little as line pressure measured in wc(inches of water column)witch is less than 1/2 psi. Changes in temperature could account for such a change did you put the pressure in when it was hot outside and check it again in the evening when it had cooled down.