Encasing Gas pipes

Discussion in 'Plumbers' Talk' started by plummit, Jan 30, 2005.

  1. plummit

    plummit New Member

    Would i be correct in thinking, that it is safe to enclose a gas pipe, as long as the top and bottom ( a vertically run pipe without joints) were vented. I ask this as the pipe looks an eye sore, and encasing it would look far better. Many thanks for your response.
     
  2. doitall

    doitall New Member

    no problem
     
  3. plummit

    plummit New Member

    Thanks do it all,
    Could i pose a question here, regarding gas standing pressure. I believe that a "soundness pressure check", is set at 20 mbars. Prior to gas passing and stabilization. The exams that i undertook, some 4 years back, stipulated this. I have recently spoken to a guy who, undertakes industrial gas work, and speaks of one and a half times the working pressure. This seems to me a better evaluation, due to the fact that the pipe work is tested to a far higher pressure. Your response would be very gratefully received.
     
  4. domestic ACS assessment, like you've done, as have I only covers upto 28mm gas pipe... for pipe sizes above a seperate ACS is required, which would cover the difference your describing.

    I agree would be better to test at a higher pressure than its normal operating pressure.
     
  5. plummit

    plummit New Member

    cheers spike,
    I understand, what you say, and am grateful for your response. But i am some what stupid (i believe ) in the fact, that the working pressure is higher that what the soundness checks are, ie 20 mmbar. Would it be possible for a pressure check on 20mbar, to sustain 2 minutes without a drop, but if we raised that to working pressure, could we possibly see a drop. I really am some what perplexed on this.
     
  6. curlydon

    curlydon New Member

    Dunno about anybody else but if I'm testing carcassing on air always jack pressure up.
     
  7. doitall

    doitall New Member

    non-domestic soundness testing aas follows.
    Calculate the system volume.
    Determine the test pressure.
    Select the appropriate gauge.
    Decide the permitted leak rate.
    Calculate the test period.
    Carryout the test.
    New installations are tested with air or inert gas and should be 1.5 times the working pressure or the fault pressure whichever is the greater.
    new installations the permitteleak rate is 0.0014, existing installations is determined by the areas it passes through and there are four categories.
    Potentially Hazardous areas 0.0014, occupied areas 0.0005, large open areas and underground pipework 0.03.
    Where the pipework passes through a mixture of areas the permitted leakage rate is that of an occupied area as potentially hazardous areas are required to be tested with leak dection fluid in addition to carrying out the soundness test.
    The smallest occupied room through which the piework passes is used to calculate the permitted leak rate.

    more ?
     
  8. plummit

    plummit New Member

    I must admit, doitall, I'm lost !!.
    Why should the tests on domestic and commercial gas appliances differ.
     
  9. doitall

    doitall New Member

    Volume and critical mass

    for example you could blow a burner up if air was allowed to remain in an incorrectly purged gas line
     
  10. r2d2

    r2d2 New Member

    "Decide the permitted leak rate"
    I don't understand this in gas work. In my own work their is no permitted leak rate and the systems are tested to anything between 18 and 30 bar.Any leak is totally unacceptable.Ragards r2d2.
     
  11. windynook

    windynook New Member

    there is a permitted leak, because low pressure natural gas is measured in m/bar and there are 1000 m/bar in
    1 bar.
     
  12. i'm gonna tick to domestic... had to read Doitall's post about 5 times before understanding it!

    On domestic installations, a permissiable drop is allowed, usually 4mbar, with appliances connected, as i suppose they allow for a slight passing on gas valves, the gas would be safety discharged thro the flue.

    however, testing a new installation, or a carcass without appliances no drop is allowed.

    it is todo with volume, if you have a miniture ultrasonic meter, then 8mbar is allowed, as less volume in system... so even thougth pressure drop may be higher, the amount of gas escaping would be similar to 4mbar drop, on a standard size meter...
     
  13. chris@vietec.com

    chris@vietec.com New Member

    A 4 mbar is permitted with gas appliances connected but with no smell of gas, even with just a 4 mbar drop if you can smell gas it's a fail
     
  14. นิà¸

    นิภNew Member

    the pressure loss allowed on a domestic carcass with appliances connected all depends on the size of gas meter and whether or not you can smell gas, if you can smell gas anywhere at all, you cannot have any pressure loss on a tightness test which is for 2 mins at 20mb. always make sure you carry out a let by test as well before you commence at 10mb for 1 min, this makes sure the meter control valve is not passing.

    permisbable pressure drops are as follows

    u16 meter 1.5mb

    u6 or g4 meter 4mb

    e6 meter 8mb

    hope this helps
     
  15. Piper

    Piper New Member

    If you're enclosing gas pipes in domestic and the enclosure is less than .01m2 no ventilation is required.
    When testing with air its 1.5 times usual test pressure - 30mb.
    I think nick33 covered everything else except there is a 1 min stabilisation between the 1 min letby and the 2 min tightness test.
    :)
     
  16. saint dave

    saint dave New Member

    Can I just point out that it is no longer called a soundness test but has been re named a tightness test, Someone , somewhere with too much time on their hands. The main diference now is the first one min you take the guage up to 10mb to test for let by. you then go up to 20mb for a further 3 min the first of these mins being for stabilisation. Shall I go into LPG? No not enough space
     

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