gas line question

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Master Brian, Oct 21, 2009.

  1. Master Brian

    Master Brian DIY Senior Member

    I have a relatively short length of gas pipe that needs to be re-worked a bit to clean things up for a basement finish job.

    My question is about testing it for leaks. Being as it would be a major job to unhook from the meter to cap it as well as capping it at each appliance, what is the best way to go about this?

    Basically, I've read the shutoff valves won't hold the 10-15lbs of pressure needed to do the test with a gauge. I have seen and used the spray bottle with soap method for making checking appliance connections. Is that a "safe" method when working with the actual line?
  2. nhmaster

    nhmaster Master Plumber

    S. Maine
    You can not test through the meter under any conditions, and a lot will depend on the inspector or the gas company as to what their testing requirements will be.
  3. Master Brian

    Master Brian DIY Senior Member

    Can you clarify "testing through the meter"? Can I leave the line hooked to the meter and test with the valve on my side of meter turned off? Or does the line need to be unhooked there?

    I thought I had read somewhere that the shut off valves wouldn't hold pressure of 10psi only about 3-4psi, that the line(s) needed to be capped.

    I did find something today saying to shut off the shut off valve(s) and install a gauge. They say it is the appliances' regulator that can't handle the pressure, that the inline valve(s) on the pipe(s) themselves can handle the pressure. So basically, just trying to figure out if I mis-understood what I read 1st or what I read today.

    I understand the gauge part, that isn't a problem, it's just what needs to be closed or capped or does using a spray mix suffice when just replacing a section.

    Basically, I need to raise the pipe up about 4", so it's out of headspace. It'll require undoing a union and a length of about 10' of 1" pipe, removing a 5" riser pipe and replacing with a piece about 9" and then reworking the other end to meet back up with the union. I figure a pressure test is best and there are shutoffs at every appliance, just curious if shutting them off and adding pressure works or if I need to cap the lines at each appliance hookup.
  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    New England
    Well, to pressure test, you have to have it disconnected from the meter, and you'll ruin the pressure regulators in any appliance connected unless you also shut off their supply valves. Then, you need a fitting to pressurize and check the pressure you apply to the pipe. My unprofessional opinion is that on a rework, not new install, just a soap test should be fine.
  5. Lakee911

    Lakee911 I&C Engineer (mostly WWTP)

    Columbus, OH
    I would agree... Soapy water.

    Either brush it on w/ an old paint brush or spray it on in a spray bottle. I've even seem some just grab some 409 or Windex (probably not a good idea though) that is laying around.
  6. hj

    hj Moderator & Master Plumber Staff Member

    Cave Creek, Arizona

    The safest test IS an air pressure one. A problem with using soap suds, (I use kid's bubble solution), is that you can miss a leak if it is on the back side of the fitting or a very slow one. Disconnect the meter, because its regulator will "dump" anything over its setting. Turn off the valves at each appliance. The common test pressure is 10 psi. IF you DO have a leak, then use the bubble solution, because then, since you know you have a leak, you will be especially diligent in looking for the bubbles.
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