Natural gas valve pressure ratings and pressure testing

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by pigrew, Jan 29, 2013.

  1. pigrew

    pigrew New Member

    Messages:
    11
    Location:
    West Lafayette, IN
    Hi,

    I'm planning to add an appliance to my house, and will want to do a pressure test of the newly installed gas lines. I'm getting confused about the pressure ratings of the various valves involved. My main shutoff says 175 PSI, but most of the appliance valves say either 1/2 or 5 PSI. Finally, I see a Nibco valve listed online <http://www.nibco.com/resources/ProductSubmittalDocs/GB1AGB2APV.pdf> that lists three different pressures: 1/2, 5, and 600 PSI CWP.

    For the nibco valve, does that mean that it would be able to withstand up to 600 PSI of (cold) air/gas pressure, but should only be used as a main shutoff for up to 5 PSI, and an appliance shutoff where the working pressure is less than 1/2 PSI? Should the other shutoff valves rated at 1/2 or 5 be able to withstand the 4 PSI of the pressure test?

    I plan to do the pressure test at about 4 PSI, with a gauge that reads up to 15 PSI. My biggest question is if I should cap off the lines before the shutoff valves, or close the shutoff valves and remove the caps on the traps so that excess pressure leaking through valves would be vented instead of damaging the appliance regulators.

    Thanks!
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,508
    Location:
    Cave Creek, Arizona
    "Excess pressure" had betten NOT "leak through the valves". If it does you have bad valves. The lines should be tested to 10 psi up to the appliance valves. Ideally, we also cap the ends of the flexible connectors and open the valves so everything is tested up to the appliance.
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