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Thread: Pressure testing a Natural gas line with air.

  1. #1

    Default Pressure testing a Natural gas line with air.

    I just ran 15 feet of galvanized pipe for my Natural gas line.
    This is a summer house so it only has a hot water heater and range.
    The gas meter is shut off and locked.
    Can a air pressure test be preformed with the gas meter shut off or does the meter have to be disconnected and a plug or cap be put on at the meter
    end. I was going to put a tee on the other end with a pump value and
    guage. I was going to put 15-20 psi in it.

    I would like to do this test before the meter is unlocked.
    Thanks.

  2. #2
    In the Trades GoTanklessToday's Avatar
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    If you pump the gas line against the meter, even with the meter off, you run a risk of damaging the meter. Natural gas runs on very low pressure. 15 psi against the mechanisms of the meter can cause plenty of trouble. The method is to disconnect the pipe at the meter. Put the test gauge on there and pump it. (I always plug all ends of the gas lines too with plugs, not just gas cocks) In Washington, our test gauge must be of the 15 psi scale. (max of 15 psi) The test must hold for 10 minutes when the inspector arrives. I usually pump to 10 psi.

    Remember that if you pump the line when the outside temperature is higher than when they do the inspection, the pressure will naturally be lower due expansion and contraction. I always beat the inspector to the jobsite on inspection day and pump the line to perfection about 20 minutes before his arrival.
    Last edited by GoTanklessToday; 01-16-2007 at 05:26 PM.

  3. #3

    Default

    Pretty much...the back pressure can damage the regulator. Either the gas meter has to be disconnected and the pipe plugged or blocked off in some manner.

  4. #4

    Default Thanks for the help.

    I was hoping for a short cut.

  5. #5
    Moderator & Master Plumber hj's Avatar
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    Default gas meter

    I test against the gas meter quite frequently. The only time I disconnect is if the regulator tries to reduce the pressure and dumps the excess.

  6. #6
    In the Trades GoTanklessToday's Avatar
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    Quote Originally Posted by hj
    I test against the gas meter quite frequently. The only time I disconnect is if the regulator tries to reduce the pressure and dumps the excess.
    Maybe it has to do with different areas, but if you do that here, you'll get an earfull from the gas company guy who comes out and takes the lock off the meter. We had one guy who pumped the gas line up so high, it ruptured something in the meter. That was expensive.

  7. #7
    Master Plumber master plumber mark's Avatar
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    Talking 15 feet of Galvanized pipe???

    Please someone correct me here because

    I am probably wrong about this.. I dont
    know where you are located in the USA....

    all I know is in most of the Midwest you are supposed
    to run BLACK Steel pipe for gas lines.....

    you claimed you ran 15 feet of Galvanized pipe...

    I dont know where you are located in the country
    and perhaps other areas allow Galvanized pipe.....

    the natrual gas in this area will attack galvainzed
    coating on the inside of the galvanized pipes and
    eventually clog up the gas valves with zink flakes.

    which can cause you all sorts of troubles......


    5 lbs of air pressure is more than enough

    ...

  8. #8

    Default

    The gas company put new lines in from the street and moved the meter to the other side of the house and they ran galvanized themselves.

    I'll do an air test with low pressure, 5 lbs shouldn't blow out the meter and
    to a soap and water check.

    Thanks again.

  9. #9
    DIY Senior Member molo's Avatar
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    No galvanized allowed here in New York State either.

  10. #10
    DIY Senior Member Cal's Avatar
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    Seen Galv . FITTINGS here in Va. ,,,,,,,,,, NEVER seen or heard of anyone being allowed to use Galv. Pipe !

    No sir

    cal

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