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  1. #1
    Join Date
    Jul 2009
    Posts
    5

    Question Outdoor natural gas fireplace questions???

    We are having an outdoor natural gas fireplace built. As I was watching the contractor install the gas line, I developed a few questions out of curiosity. The fireplace is built out of 8" X 8" X 16" CMU. The gas line comes from underground through the footer and into the CMU (see photo). Should the gas pipe be vented since it is enclosed in the block? If so, how? I doesn't look vented. I also had another question. When the gas line was inspected, the contractor tested it at 60 PSI for 15 minutes (PE pipe). Since gas is so dangerous, why is it only tested for 15 minutes? It seems that a slow leak would not be visible in only 15 minutes. As a note, I live in Surprise, Arizona.

    Thanks
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  2. #2
    Join Date
    May 2005
    Location
    Madison, WI
    Posts
    1,078
    The gas line is normally going to have a pressure of 2 PSI or less (standard house pressure here is 1/2 PSI). At 60 PSI a small leak would be evident fairly quickly. Every city around here is different for gas line testing, some want as little as 10 PSI for 15 minutes, where some want 30 PSI held overnight.

  3. #3
    Join Date
    Jul 2009
    Posts
    5

    venting gas pipe

    Do you have any insight on the venting of the gas pipe in this situation (see image in previous post)? Before the mason encloses the pipe in the block, I would like to find out the if the gas pipe needs to be vented in some way. Is this the normal way to construct an outdoor fireplace, or are the contractors doing something wrong or dangerous by enclosing the pipe, fittings, and key value in the block?

    Thanks

  4. #4
    Join Date
    Jan 2009
    Location
    Indiana
    Posts
    3,228
    they key valve should be accessible without taking anything apart..i.e. visible
    only reason a vent would be needed is if there is a regulator of some kind on the device.

  5. #5
    Join Date
    Jul 2009
    Posts
    5

    venting gas pipe

    The key value will be accessible as far as using it to turn the gas on and off. If it needs to be replaced, the block will have to be opened up to access it. If the gas pipe leaks when it is enclosed in the block, doesn't it need some way to vent to the outside to prevent gas buildup?

  6. #6
    Join Date
    Dec 2003
    Posts
    81
    No, gas lines are run thru walls and floors all the time. There are pipes 50+ years old that do not leak. Most leaks occur where steel pipe contacts earth (rust) or at fittings where appliance or such are attached.

  7. #7
    Join Date
    May 2005
    Location
    Madison, WI
    Posts
    1,078
    I think if you run a CSST (stainless flex) gas line they want you to sleeve it and you have the option of getting a vented fitting on one end, but I can't remeber if it is required or not.

    Found this in the design guide for the CSST we use

    When piping is installed underground
    beneath buildings, codes require that the
    piping shall be encased in a conduit
    sealed inside of the building and vented
    above grade to the outside. The conduit
    shall be designed to withstand the superimposed
    loads. NO FITTINGS OR COUPLINGS
    ARE PERMITTED BENEATH
    BUILDINGS.

    http://omegaflex.com/trac/technical/...Omega_Flex.pdf

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