Gas line pressure test

[davidmash]

Buying a house to flip and the gas meter has been d/c'ed a while ago. They converted to electric. Seems the lines and out lets are all still in place. Has anyone ever pressure tested the lines? Seems like I could buy a pressure gauge and valve, screw it in and pump it up with a compressor to 40 or 50 psi, let it stand and see what happens.

[Txjake]

Originally Posted by davidmash

Buying a house to flip and the gas meter has been d/c'ed a while ago. They converted to electric. Seems the lines and out lets are all still in place. Has anyone ever pressure tested the lines? Seems like I could buy a pressure gauge and valve, screw it in and pump it up with a compressor to 40 or 50 psi, let it stand and see what happens.

what's the goal? To hook up gas again? what does the code say about that? most likely a violation if you are not licensed and start mucking about with gas lines.

[kerry]

Yep, that's what you do. I've personally done it to my hot water radiator heating system and watch the gas company do it to the gas system on one of my rental properties. I think code says it has to hold x pressure for x number of hours. Gas is pretty low pressure but the test pressure was quite a bit higher.

[Idle]

I saw this done once on a house in Grand Prairie, so Arlington might be pretty close to the same regs.

Lone Star (Yeah, it was that long ago) tapped the line out by the street and isolated the line to the house from the street with a stopple. They then injected nitrogen until they had reached three times the working pressure which meant taking it to 60 psi. The line leaked so they sleeved it with a piece of that plastic pipe and tested it again. That time it held.

If you hook up to the existing outlet you will see line pressure and nothing more. If you tried to pressure the line you would need a semi load of N2 since you would be pressuring up the entire system as you would have no way of shutting off the flow to the mains.

A better way to find a leak would be to either rent a hydrocarbon detector and run it up and down the line. These thing are meant to pick up hydrocarbons which are lighter than air and will make their way to the surface.

You could also contact the local gas utility who might come out and check with their hydrocarbon tester for free but if they do find a leak they will want to repair it and since it is on your property they will then send you the bill.

I can understand you would want to know this, but if you are never going to use the line then why are you concerned?

[kerry]

No need for nitrogen as far as I can see. Air is fine.

[Idle]

Originally Posted by kerry

No need for nitrogen as far as I can see. Air is fine.

They use N2 because it is free of water vapor and will not combust.

Really. Air will introduce water and oxygen and over time this will rust out the pipe.

I had to be there and witness everything so I asked a lot of questions of the Lone Star guy. It took three hours.

[SwampYankee]

Originally Posted by davidmash

Buying a house to flip and the gas meter has been d/c'ed a while ago. They converted to electric. Seems the lines and out lets are all still in place. Has anyone ever pressure tested the lines? Seems like I could buy a pressure gauge and valve, screw it in and pump it up with a compressor to 40 or 50 psi, let it stand and see what happens.

I take it you want to pressurize the gas lines that are in the house and no longer connected to the main in order to see if they maintain pressure so any potential buyers would know the lines inside the house are safe if they decide to go back to gas, correct?

[kerry]

Originally Posted by Idle

They use N2 because it is free of water vapor and will not combust.

Really. Air will introduce water and oxygen and over time this will rust out the pipe.

I had to be there and witness everything so I asked a lot of questions of the Lone Star guy. It took three hours.

There are drip legs in interior gas lines to deal with that problem. Maybe in the street lines N2 is necessary. His line is already filled with air.

[davidmash]

Originally Posted by SwampYankee

I take it you want to pressurize the gas lines that are in the house and no longer connected to the main in order to see if they maintain pressure so any potential buyers would know the lines inside the house are safe if they decide to go back to gas, correct?

Yes. If the lines are good and it does not cost to much to get a meter installed I want to put a gas stove top instead of electric.

[97 SL320]

You need a " Kuhlman Gauge " Kuhlman is a brand but is used like Band Aid , Jello. Compressed air is fine, these gauges have a hand pump / bicycle pump.

It is a chamber ( Manometer ) with liquid that will bubble if pressure in the line drops. The test takes 5 minutes or so, not like pumping things up then waiting overnight.

Do a search and someone will have a vid / animation of how it works.

[kerry]

plumbing - How do I pressure test a natural gas line and what do the valve pressure ratings mean? - Home Improvement Stack Exchange

[davidmash]

Cool. Thanks for the info. Once we take possession we will have to see if it is worth it. I need to call the gas company as well to see what their fees and requirements are.