Ask Me Help Desk - NG pipe pressure testing

NG pipe pressure testing

My old house (<1940s) had NG going to almost every wall in the house for old space heaters. I am doing some updating and I shut off the gas and removed all the old pipes except for the originating line entering the pier and beam crawlspace. The main line is 1.25" and reduces after an elbow to 1". I ran new line to the attic heater (with a catch) and to the range. I pressure tested the system at 10 psi on a 15psi meter and had a less than slow leak. Upon spraying all connections, the leaks are outside of the house at the piping on the right hand side of the meter, mainly the union connecting to the meter. I didn't disconnect the meter so as to not disturb the system and thought it would be okay given Dolezal's advice here:

https://www.askmehelpdesk.com/plumbing/how-pressure-test-gas-pipe-11521.html

I previously "trusted" the old gas system, the new lines have no leaks, and the leaks are at the exterior piping/ meter union and meter top seal.

How do I address this? Thanks for your help.

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the leaks are outside of the house at the piping on the right hand side of the meter, mainly the union connecting to the meter.the leaks are at the exterior piping/ meter union and meter top seal.

There should be no leaks whatsoever, no matter how small. Have you tightened the union and checked again? What side of the meter is the union on? The house side or the street side? And if the meter has a seal leak then the gas company should either repair or replace it. Have you contacted the gas company about this problem? Let me know, Tom

Tom, thanks. The union is on the right hand side (all leaks are to the right of the street pip & valve. I tightened the union at the right meter exit about a 1/4 turn or maybe a 1/2 and retested. There is a very small leak now - the only part I was able to find at 7psi is the meter top seal - very slowly with small bubbles. I don't have a permit for my work. (I understand the idea behind permits but I am very detailed and thorough about doing things correctly so I didn't get one.) I suppose I should contact the gas company now to have them assess the meter.

Thanks,

If all that's leaking is the meter seal then contact the gas company and have them replace the meter. Good luck, Tom

Hi PB

You would want to disassemble the union and then reassemble and tighten again using 2 wrenches, or call the gas company as Tom suggested, OK?

Also, you aren't testing through the meter are you? If you are, you shouldn't be... could rupture the diapragm and that will cost a pretty penny to fix as the gas company knows that the diaphragm almost always bursts due to a homeowner testing through the meter... ;) Here, disconnect the meter and cap the line or test from that spot. Be sure to isolate the work (disconnect at the union of the appliance) so you don't overpressurize the gas valves and break them, OK?

Finally, you said a 15PSI meter... and only 10 PSI for your test... please explain that, OK? You are still delivering gas to the appliances at 1/2PSI, right?

Thank you...

Mark

You have to disconnect gas meter from piping for test purposes. No way around it. Also, remove all valves from the new system. Plug all ends with metal cap. Then attach gauge and retest. Back to you. Milo

Speed, Mass & Milo,

Thanks for your replies. I appreciate the information.

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you said a 15PSI meter... and only 10 PSI for your test... please explain that, OK?

My code is 15 minutes at 10psi on a 30psi gauge with "an appropriate scale such that pressure loss can be easily determined." I ran my pressure tests at 10 psi for 15 minutes on a 15psi meter with 0.1psig markings. Is there a reason I should rather have used the full range of the meter?

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You are still delivering gas to the appliances at 1/2PSI, right?

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I am not sure what you mean by "still," but that is what the ng line pressure is here/ will be to the appliance.

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if the meter has a seal leak then the gas company should either repair or replace it. Have you contacted the gas company about this problem?

I haven't contacted them (yet?). I figure they'll want to know why/how I know there is a seal leak...

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you aren't testing through the meter are you?. so you don't overpressurize the gas valves and break them, OK?

I did not disconnect the gas meter during my test, so I tested through the meter (?). I thought that it wasn't necessary since the incoming valve was closed, and I didn't want to disturb any of the old connections. Is it likely I did damage to the meter/ diaphragm? I understand that was wrong. I should have opened the right hand union, loosened the left hand union (after closed valve) and rotated the meter away to allow for capping or the test gauge. Correct? Can I totally disconnect the meter, set on ground, test, then reconnect?

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Also, remove all valves from the new system. Plug all ends with metal cap. Then attach gauge and retest.

I had capped the attic line and tested at the range stub, however, have since added ball valves at both locations. So, to confirm, I cannot test from the meter against the two ball valves? I must remove, recap and test? Do (ball) valves leak at pressures higher than 0.5psig?

Thank you very much for your help.