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  • Teflon Tape

    Putting a new fitting(gas outlet) in my argon/co2 mig gauge.

    Is it o.k. to use teflon tape on the threads.

    Seems like somewhere I read teflon tape was a no-no on something!

    Thanks
    John1

  • #2
    Just to be on the safe side, I'd use the teflon paste if needed. That will prevent a possible flake of the tape from entering your system. It is a "no-no" on a plasma cutter.
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    • #3
      John,

      If you're talking the low pressure outlet, why bother with tape? There isn't enough pesuure there to leak past a loose fitting! I'd wrench it up snug and call it good.

      Hank
      ...from the Gadget Garage
      MM 210 w/3035, BWE
      HH 210 w/DP 3035
      TA185TSW
      Victor O/A "J" series, SuperRange
      Avatar courtesy of Bob Sigmon...

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      • #4
        Hank, it will bleed down over time, which means that you're always wasting a little gas. If you do like I do, and occasionally forget to close the bottle at night, then you could wake up to it being empty.

        I make sure my machines don't leak down and do whatever needs doing to fix it (like was the case on my tigmate) if they do. Pipe dope has always been my preferred method.

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        • #5
          Jim,

          All three of my machines bleed down after they are shut off. The MM135 is the fastest, the TA the slowest. I've left the C-25 open on the 210 for a week (once!) and didn't seem to loose any appreciable amount of gas. It never seemed important enough to chase the leak. Maybe if I get boored today, I'll go play with it. Can't weld - no steel!

          Hank
          ...from the Gadget Garage
          MM 210 w/3035, BWE
          HH 210 w/DP 3035
          TA185TSW
          Victor O/A "J" series, SuperRange
          Avatar courtesy of Bob Sigmon...

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          • #6
            I use the tape, just don't wind it past the end of the fitting and it won't get in the hole....Bob
            Bob Wright, Grandson of Tee Nee Boat Trailer Founder
            Metal Master Fab
            Salem, Ohio
            Birthplace of the Silver & Deming Drill
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            • #7
              I'm just **** like that I guess. I never closed the valve on my 130XP - it didn't leak at all. My new machines I just got back into the habit of closing them again, leaving them open got me into a bad habit and it has bit me at some other shops. They don't leak, I just close them.

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              • #8
                Brass seals brass, so teflon tape is not needed. However, Telfon tafe should never be used, instead go for a small amount of paste on other fittings.

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                • #9
                  Originally posted by ventureline
                  Brass seals brass, so teflon tape is not needed. However, Telfon tafe should never be used, instead go for a small amount of paste on other fittings.
                  I certainly do not wish to put in my two cents, however (That means I'm gonna anyway ) I was (Still am) a master plumber for nearly 15 years and water hasnt been told that brass seals brass! Pipe dope (Rectorseal) hardens with time and can be a real bear when it comes time to remove fittings. Teflon paste is good, messy and ends up where you dont want it. On medium pressure Natural gas, low pressure Natural gas and high and low pressure LP (Propane) as well as water and air your best bet is good old teflon tape. Be sure not to wind the tape past the end of the thread and wind the tape on so when you screw in the fitting, it goes the proper direction. (Dont know how to explain it) If you wind in the wrong direction as you screw in the fitting, the tape may try to "Unwind" and end up inside the pipe.

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                  • #10
                    I'm with Meach. Though I ain't been no plumber, I've used all the above. Teflon tape is the easiest, and I still have good fittings that were sealed with it decades ago.

                    Example of where to use it would be on the gauges where they thread into the regulator body. The threads do the sealing here.

                    Example of when not to use it would be where the regulator body mates to the valve on the cylinder. This is where the threads push two brass mating surfaces together, and they do the sealing, not the threads.

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                    • #11
                      Originally posted by Meach
                      I certainly do not wish to put in my two cents, however (That means I'm gonna anyway ) I was (Still am) a master plumber for nearly 15 years and water hasnt been told that brass seals brass! Pipe dope (Rectorseal) hardens with time and can be a real bear when it comes time to remove fittings. Teflon paste is good, messy and ends up where you dont want it. On medium pressure Natural gas, low pressure Natural gas and high and low pressure LP (Propane) as well as water and air your best bet is good old teflon tape. Be sure not to wind the tape past the end of the thread and wind the tape on so when you screw in the fitting, it goes the proper direction. (Dont know how to explain it) If you wind in the wrong direction as you screw in the fitting, the tape may try to "Unwind" and end up inside the pipe.

                      ditto. they also sell 2 thicknesses of teflon tape. thin white tape and thicker yellow tape. and who came up with that brass seals brass...i've seen many brass fittings leak water at 70 psi....there are tapered fittings that seal themselves as you tighten them...i've only seen them on black iron however.

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                      • #12
                        There are 2 types of pipe threads. Common plumbing pipe threads have flat not sharp outer edges that leak if not sealed with pipe dope, tape or something. High pressure pipe threads come to sharp V at outer edge and sharp V at inner V so they seal better. Look at your Argon cylinder valve pipe thread connection. They don't use Teflon tape, dope or anything if it is steel cylinder. They just tighten real tight. Same is true for all the pipe thread fittings on my argon regulator. Cylinder valve is in so tight the threads are damaged and can't be reused many times. I've been told the cylinder valves with pipe threads are replaced after hydro. When I was using scuba cylinder valves with pipe threads with teflon tape the threads were so damaged I mught use old valve a couple of times. We had to visually inspect inside scuba cylinders once a year for rust. If your HP cylinder is aluminum then must use teflon tape or approved lubricant to prevent cylinder thread damage.

                        USN had someone use damaged pipe threads that would not seal until many layers of teflon tape was used. This cludge lasted long enough to cause an accident. They only allow 2 layers of teflon tape 1 to 2 threads away from end. Pipe dope and Teflon paste should also be placed 1 to 2 threads away from end. They all have to be removed from threads when they are taken apart. I have use brass O-ring pick made from brazing rod or awl to clean clean threads.

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                        • #13
                          teflon

                          I've always had very good results using Harvey's paste with Teflon and other paste products with PTFEI. do use Teflon tape sometimes on small fittings but for bigger jobs such as 1/2 pipe and bigger I always use a paste with Teflon in it. I also have did plumbing for many years and we've run a bunch of 3/4 and 1 inch black pipe for gas installations with very few leaks..less than1%
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                          • #14
                            Teflon tape clogs up the solinoid screens and lines, don't use it. Teflon tape is NOT recommended on any (welding related)brass to brass connections. I merely mentioned that if you really had to use some sort of tape. then use a very small quantity of teflon paste. Works better and doens't clog up critical components.

                            Hmm, your brass tank connector seals and mates with your argon flow meter at 3000+ psi.


                            In aircraft, you won't find any teflon tap on any fittings, and brass does seal brass, providing the threads are the same. In the last 20 years of welder repair I don;t bother taping brass fittings. Though I'm not a plumber. I bubble check all my connections and haven't found a leak yet....
                            Last edited by ventureline; 01-22-2006, 11:46 AM.

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                            • #15
                              It's hard to generalize threaded fittings.

                              You have to deal with each type as you encounter it. Brass flared fittings are designed to seal themselves. Inverted flare fittings are used on high pressure applications, like break lines, and are self sealing. Iron pipe unions have machined mating surfaces, and are self sealing on the union side, but the NPT (tapered) side will need teflon (or dope). The 9/16 - 18 fittng on O/A hoses is designed with a machined mating surface; self sealing. There are lots of applications for NPS (straight pipe thread) fittings, all of which need a sealant.

                              The generally accepted practice for welding gas fittings don't specify any sealant. Of course, there are those who do it their way, regardless of what the "standard" may be!

                              Hank
                              ...from the Gadget Garage
                              MM 210 w/3035, BWE
                              HH 210 w/DP 3035
                              TA185TSW
                              Victor O/A "J" series, SuperRange
                              Avatar courtesy of Bob Sigmon...

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