Are Compression Fittings Ok For Gas ?

Discussion in 'Plumbers' Talk' started by hjm218, Feb 24, 2006.

  1. SDSMax

    SDSMax New Member

    if you don't want to use tape then use some 'Boss White' jointing compound.
     
  2. Tiff

    Tiff New Member

    Take a good long look at each type of joint you are using, find out and understand how that joint works - just exactly how is a seal supposed to be made, then apply ptfe (correctly) if you think it is needed. In my experience ptfe is only ever requied on a tapered thread, and even then used sparingly. compression joints (olives) do not need ptfe to seal, if you are relying on ptfe as a "secondary" seal then you are not using the joint correctly. Some instances require an absence of anything that can remotely get into the system (safety systems on industrial plant etc) in that case use Boss white or other proprietory sealent, I have seen delicate pneumatic instrumentation blocked by particles of ptfe that should not have been there. Whatever you decide to use, please use as little as is needed, excess is wasteful and detrimental to safe operations.
     
  3. SDSMax

    SDSMax New Member

    Ptfe tape should never be used on a COMPRESSION
    fitting.It is only used on a male/female gas thread
    and of course should be the thicker,usually yellow
    gas grade ptfe tape.



    You are going to blow yourself up, other people around you and take out the side of someones house!

    <u>Plummit</u>- you talk alot of sense mate and you've certainly got my respect.


    WS - put away your 'Gas Fitting for Morons' book and get something more informative to read!
     
  4. glynmitch

    glynmitch New Member

    SDS Max,

    Surely Boss White is for non potable water, Boss Blue is for potable water and Gas Tight is for eh.....gas!


    Glyn
     
  5. SDSMax

    SDSMax New Member

    eh...you can use either!
     
  6. doitall

    doitall New Member

    I wasn't intending to get involved in this but since SDS Max post I thought I better.

    Boss white should not be used on gas joints because it hardens.

    As for the ptfe debate on compression fitting :D:D

    Jet blue around the fitting side of the olive is all thats needed, it costs peanuts, guarantees the joint, and as plummit said could save you a lot of unpaid work and embarrassment draining down.
     
  7. SDSMax

    SDSMax New Member

    you are wrong! Boss White is non hardening.
     
  8. Water Systems

    Water Systems New Member

    you are wrong! Boss White is non hardening.

    If it says suitable for natural gas, it doesn't harden.
     
  9. Water Systems

    Water Systems New Member

    Ptfe tape should never be used on a COMPRESSION
    fitting.It is only used on a male/female gas
    thread
    and of course should be the thicker,usually yellow
    gas grade ptfe tape.



    You are going to blow yourself up,
    other people around you and take out the side of
    someones house!

    <u>Plummit</u>- you talk alot of sense mate and
    you've certainly got my respect.


    WS - put away your 'Gas Fitting for Morons'
    book and get something more informative to read!

    Another one who doesn't know much. Plastic pipe makers stiplulate that PTFE is wrapped around the olive when using compression fitting with plastic pipe.

    What moronic book are you reading this week?
     
  10. doitall

    doitall New Member

    Interesting, an apology is in order SDSmax

    They must have changed it because it was never suitable for gas.
     
  11. hjm218

    hjm218 New Member

    When using compression fittings, is it always
    necessary to tighten the nut for a full turn ?

    I've found it difficult to get enough leverage
    on the spanners when using them in a confined
    space like under the sink.

    Any tips on this anyone ? Best way to get the
    right leverage ?

    John
     
  12. Water Systems

    Water Systems New Member

    When using compression fittings, is it always
    necessary to tighten the nut for a full turn ?

    I've found it difficult to get enough leverage
    on the spanners when using them in a confined
    space like under the sink.

    Any tips on this anyone ? Best way to get the
    right leverage ?

    John

    An open ended ratchet spanner.
     
  13. screwfox

    screwfox New Member

    So HJM218 first you "happened to notice" the gas pipe had been extended with compression, and was this ok.

    Then you asked about PTFE on compression joints.

    Now you say you find it difficuly to get leverage to tighten a compression joint under the sink.

    Admit it, you're extending a gas pipe, are you competant?
     
  14. Nowater290

    Nowater290 New Member

    Hi all
    help with this one, moved gas pipe 3 inches over to allow for an island every thing was soldered part from the joint between new and old pipe work which was a compression joint that was , joined with gas mate paste ( felixable)and tested with soap spray. The reason i used compression was: 1 because I didn't want to disconnect the gas at the meter and put a flame in a very small space with very limited access and 100 year old dry as tinder beams floor boards.

    I left a small piece of the bamboo flooring free that can easily be removed so its accessible, its not glued or screwed and its obvious as its under the seating area of island. I Thought i could smell gas in hallway (flats) the other day and called the gas company. Full flat test no pressure drop however the engineer said the compression fitting was illegal as its under the floor. I would agree if it was hidden and inaccessible it would be illegal however it is accessible . Any ideas, I would not have attempted it if i didn't feel that i was competent to join the pipes without leaks. But it looks like i may have not had my regs right! any advice where can I find out. Apparently the smell is probably dead rotting mice!!!
     
  15. Glad its Friday

    Glad its Friday Active Member

    Without seeing exactly what you've done it is a bit difficult to comment. But if the comp fitting is accessible then ok as far as I'm concerned. But tut - you've done illegal gas work, why would you risk it? But lets not go there........
     
  16. Tallulubloodylah

    Tallulubloodylah New Member

    Never use sealant on compression fittings. If they leak you have not installed it correctly. When you insert the pipe into the fitting you should pull it back out sufficiently to allow it to be drawn back in when you tighten the nut, thereby allowing the olive to seat tightly. Your mistake is pushing the pipe in all the way before you tighten the nut. I am an engineer. If you don't believe me ask NASA.
     
  17. Dave does Gas

    Dave does Gas Screwfix Select

    Why are you dragging up ten year old threads?
     
  18. 'Cos he likes the sound of his own voice?

    (Okay, okay, okay - bludy 'rony, yeah yeah yeah... :rolleyes: )

    BUT, I neffer thought of that point he made - as the compression nut tightens aroon' the olive, it will also be pushing the olive into the compression fitting body towards the pipe end by a few mm and, if the pipe has been bottomed-out inside the fitting body, then the olive will have to be sliding on the pipe as well as trying to clamp and seal.

    And, given the lots of heating and cooling over the years, since the olive is 'trapped' in that one place on the pipe, it'll have to suffer a back-and-forth pulling action for ever more...

    Has Tallu chust pointed out something almost quite important?
     
  19. Craig Beall

    Craig Beall New Member

    Not sure how the terms "ptfe tape" and "sealant" even entered this thread in the first place. The whole reason compression joints were originally invented was to avoid sealants and tapes.
     
  20. dubsie

    dubsie Active Member

    They are but they have to be accessible for maintenance and inspection....not behind a kitchen unit or under the floor.

    I went to a job and when I cut into the pipe there was excessive play. On inspection I found a compression fitting under the floor. It passed a tightness test but could be un done with your fingers. It maybe that I loosened it by cutting the pipe the other side of the wall or it could have been loose all along.

    So acceptable in the right context....look under your boiler....no doubt you will find compression under there.

    Gas is under very low pressure...mb...you can fart more pressure. But this makes its even more dangerous....poor workmanship or simply forgetting to tighten or solder a fitting can cause a disaster. The tightness test may not even pick up a mistake. We have all been there and when you find a small leak you intially attempt to know up the fitting.....if that works brilliant but getting the paste out to fix a leak is a bad move

    You can paste the olive but there should be no need and if it's leaking fix it rather than paste because the paste can hold back a leak and dry out weeks later only to leak again.

    Gas is not a DIY subject and can land you in a world of hurt if it goes wrong. For what it costs get a gas Safe plumber to correct it
     
    Last edited: Nov 25, 2020

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