Are Compression Fittings Ok For Gas ?

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

  1. hjm218

    hjm218 New Member

    Hi all,

    When doing our kitchen, I noticed that the gas
    pipe for the cooker must have been extended
    and moved at some point using compression fittings.

    Are compression fittings ok for gas or should they
    be replaced for soldered joints ?

    Thanks in advance.

    John
     
  2. rama

    rama New Member

    Yes compression are perfectly suitable for gas.
     
  3. SDSMax

    SDSMax New Member

    make sure you use gas grade PTFE tape on the compression threads.
     
  4. Thats IF you use PFTE, then ensure it is gas grade. Many people don't use PTFE on compression joints and is fine!

    The regs say compression joints should be accessible, and not within voids, or under floors.
     
  5. rama

    rama New Member

    I can't believe the number of pros that use PTFE on threads when in the union is made between the olive and the face of the fitting. Gas tight or similar should be used on the olives.
     
  6. bernieeccles

    bernieeccles 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.
     
    RobJamesHeating likes this.
  7. Its not yellow, its white!!! lol :)
     
  8. plummit

    plummit 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 joking right ??.
     
  9. chris@vietec.com

    chris@vietec.com New Member

    Why do people keep going on about putting PTFE tape on compression fittings, you most certainaly do not use PTFE on a new compression fitting and if you read up on info from the likes of Conex they actually state that there is no need for any compounds eg Jet blue etc to be used
     
  10. plummit

    plummit New Member

    Hello chris@vietec.com,
    I would always dress an olive, and this is through experinence. The saga continues I suppose, but have had dry compression fittings leak.
    I really couldnt give a flying f&%K what conex say, I use their fittings, from 15mm up to and over 2 inch compression fittings.
    I have yet to have a dressed fitting leak, but definately had undressed fittings weep.
     
  11. guess just do what ever suits you! I personally use compression (upto 28mm) without any sealant, and all is good.

    If u prefer to use a compound or PTFE, then why not! :)
     
  12. Water Systems

    Water Systems New Member

    I can't believe the number of pros that use PTFE on
    threads when in the union is made between the olive
    and the face of the fitting.

    The amount of plumber I see do this is amazing. Quite a few I have told them that it seals nothing whatsoever. They respond by saying it does. I then say to them look at the fitting and see where the seal is being made. I also point out that the nut on a compression fitting is to pull the olive onto the fitting body - nothing else. And in putting on PTFE on the thread you may prevent the fitting being fully pulled together.

    Some look at the fitting and clearly can't understand how it works. Others say I've always done this and never had any problems. I came across leaks on a diesel pipeline system. 1/2" BSP iron fitting with taper unions. The thick PTFE prevented the tapers on the fitting from mating properly - they could not be pulled together full as the PTFE on the union nut threads acted as a spacer. I told them to take the PTFE off and tried to explain. I stripped the PTFE off and put a smear of compound on the taper and did it up to no leaks. They still put PTFE on the threads. Some people are clearly thick.
     
  13. plummit

    plummit New Member

    Watersystems,
    I too would be surprised if fitters used a jointing compound or ptfe on the threads.
    As you correctly said, the seal is made via the olive.
    We are talking about metal sealing against metal, all be it brass or copper. The time it takes to add a "sealant" is more than worth while in my opinion.
    Just wondering why on cars gaskits are used.
    We could argue about this all night I suppose.
    I will not change your views and you will not change mine.
     
  14. Andy Fish

    Andy Fish New Member

    You must know some of my mates! I can't get the message through either!

    Ban the bomb and PTFE as well!

    Fish
     
  15. plummit

    plummit New Member

    Each to their own I guess Andy, as long as a seal is achieved.
     
  16. plummit

    plummit New Member

    We tend to work on high pressure water systems, and also on big bore pipe work. We are a plumbing company that mainly deal with commercial installations. If a plumber decides against using dressings on a compression fitting, then that responsibility rests upon his shoulders. If a leak, or weep should occur, he is on his own. Feel free to go back to a six inch main and drain down. I can only say it as I have seen it.
     
  17. handyman 2

    handyman 2 New Member

    I have a mate who is a Gas Fitter and he decided to service his aging Citroen car. Doing so he wrapped PTFE tape around the spark plug threads, it must be a case of 'see a thread - PTFE it' lol
    Anyhow once everything was back together he couldn't start the car and spent several hours re-doing everything looking for the fault - I got a call and ten minutes later after rolling on the floor laughing, we removed the spark plugs and cleaned the threads before putting them back in - he'd wrapped PTFE around them and insulated them as a result so no connection was made to make a spark
     
    JH787 likes this.
  18. Rama said ""I can't believe the number of pros that use PTFE on threads when in the union is made between the olive and the face of the fitting.""

    I think that the answer is that a real pro does NOT use PTFE tape on the threads of a compression fitting.

    Sometimes, it may help to put a little PTFE taps around the olive if a poor seal is expected.

    It also helps to put a small amount of silicone on the olive and the thread. This acts as a lubricant and helps the olive slide and deform to form the seal whereas if the thread is lubricated it gives more pressure for the same torque.

    Tony
     
  19. SDSMax

    SDSMax New Member

    I think that the answer is that a real pro does NOT
    use PTFE tape on the threads of a compression
    fitting.

    What an appalling statement and you should be ashamed of yourself!

    PTFE is used as a secondary seal just in case the primary seal (olive) fails, and to suggest that PTFE can hinder the correct tightening of a fitting is ludicrous because it wont give that much resistance for this to happen - not unless it's wound on half an inch thick! the real pros do use PTFE on compression threads! even more so on a gas joint because gas doesn't have the surface tension that water has and will escape through the minutest failure point.
     
  20. hjm218

    hjm218 New Member

    Thanks for all the replies - They're much appreciated.

    If you were to use a sealing compound for compression
    joints instead of PTFE, what would be the best?

    Thanks again

    John
     

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