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Thread Jointing compound or PTFE at JIC and NPP threads etc

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  • Thread Jointing compound or PTFE at JIC and NPP threads etc

    I might be told off by the Idi Admin for putting this in the wrong section, but I reckon a pro will do this one easy. (should it be in the safety section?)

    Now I've been told (by a scuba guy) I can use PTFE tape on taper and straight pipe threads and on stripping my Coltri down I see it left the factory with what looks like the remnants of a paste. I'm talking about the threads in and around the cylinder head where it gets hottest. PTFE is going to melt. Thus my questions:

    1. On a taper-fitting like a JIC or similar I assuem no tape or cement compound is required on threads (the taper does the work), correct?
    2. On a tapered-pipe thead away form heat is PTFE OK, what about fire?
    3. Where we have heat I assume we use a cement?
    4. Where is it OK to leave it dry?
    5. I notice the fitting on the back of my Wika pressure gauge has no apparent taper, how does that seal?

    Wika Guage.jpg

    Please fellas, what gives?
    BritCNGUser
    Senior Member
    Last edited by BritCNGUser; 04-07-2014, 02:32 PM.

  • #2
    Re: Thread Jointing compound or PTFE at JIC and NPP threads etc

    as a former tech for Parker-Hannifin i can tell you do not use any thread tape on anything but thread to seal fittings (such as NPT) jic/oring/jis style fittings will seal with their respective orings/flares. ptfe/sealing compounds do nothing but compromise the integrity of the seal

    i personally use the HD gray sealing compound with npt joints. i was told by one of my engineers that ptfe tape can break off and if a small piece lodges in the line it can impede flow, so i only use the paste

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    • #3
      Re: Thread Jointing compound or PTFE at JIC and NPP threads etc

      Thanks. Is HD gray a branding for a generic product. I've tried Googling it. I'm guessing 'Gray' as in colour grey, not Surname. Apart us spelling Gray with an 'e' I'm a bit lost. Is there a generic term for this elixir?

      Is it the same thing as a plumber might use, or rather more magical? And I forgot, how best do you cut that stainless pipe cleanly. In plumbing I have a copper pipe-cutter, but I don't reckon it'd be good for S/S. How does a pro do it?

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      • #4
        Re: Thread Jointing compound or PTFE at JIC and NPP threads etc

        http://www.homedepot.ca/product/pro-...t-500ml/966902

        http://www.oatey.com/products/thread...joint-compound

        rigid makes a pipe cutter/threader that will work for SS
        trdscfjc
        Senior Member
        Last edited by trdscfjc; 04-07-2014, 08:15 PM.

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        • #5
          Re: Thread Jointing compound or PTFE at JIC and NPP threads etc

          On NPT I use PST 567 over 3 wraps of yellow Teflon tape, try to leave the first thread bare. This is what Hoke & Swagelok recomends.

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          • #6
            Re: Thread Jointing compound or PTFE at JIC and NPP threads etc

            I cut stainless steel tubing with a hacksaw or a cut off wheel. Deburr the cut inside and out and assemble. A tubing cutter usually leaves a lip on the inside of the tube that could be restrictive.

            Karl
            Originally posted by BritCNGUser View Post
            Thanks. Is HD gray a branding for a generic product. I've tried Googling it. I'm guessing 'Gray' as in colour grey, not Surname. Apart us spelling Gray with an 'e' I'm a bit lost. Is there a generic term for this elixir?

            Is it the same thing as a plumber might use, or rather more magical? And I forgot, how best do you cut that stainless pipe cleanly. In plumbing I have a copper pipe-cutter, but I don't reckon it'd be good for S/S. How does a pro do it?

            Comment


            • #7
              Re: Thread Jointing compound or PTFE at JIC and NPP threads etc

              I've found ebay to be my friend here, me and Ebay - it's usually a love-hate realtionship... Loctite 567 is a Stainless Jointing compound available in non-stonking great tubs (read cheaper) for rank amateurs like yours truly. Cost me £12.00 (about USD 17-18). whereas the other products are in quantities good if you do this lark for a living. Job done. Thanks gents.

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              • #8
                Re: Thread Jointing compound or PTFE at JIC and NPP threads etc

                Originally posted by BritCNGUser View Post
                I might be told off by the Idi Admin for putting this in the wrong section, but I reckon a pro will do this one easy. (should it be in the safety section?)

                Now I've been told (by a scuba guy) I can use PTFE tape on taper and straight pipe threads and on stripping my Coltri down I see it left the factory with what looks like the remnants of a paste. I'm talking about the threads in and around the cylinder head where it gets hottest. PTFE is going to melt. Thus my questions:

                1. On a taper-fitting like a JIC or similar I assuem no tape or cement compound is required on threads (the taper does the work), correct?
                2. On a tapered-pipe thead away form heat is PTFE OK, what about fire?
                3. Where we have heat I assume we use a cement?
                4. Where is it OK to leave it dry?
                5. I notice the fitting on the back of my Wika pressure gauge has no apparent taper, how does that seal?

                [ATTACH=CONFIG]4196[/ATTACH]

                Please fellas, what gives?
                1. JIC is a metal to metal seal so no tape.
                2. Tapered thread, PTFE works great! If your compressor gets high enough temperature to start a fire, you have a LOT more to worry about than thread sealant! PTFE is rated for continuous use to 260F.
                3. Again, PTFE works great. I use a paste simply because it is easier to work with.
                4. Dry fittings are only acceptable on JIC or compression fitting.
                5. That pressure gauge is a strange one. It is actually a tapered thread but not as much as pipe thread. Again, the paste is what we use.
                Ray Contreras
                CompressorStuff.com

                Comment


                • #9
                  Re: Thread Jointing compound or PTFE at JIC and NPP threads etc

                  5. That pressure gauge is a strange one. It is actually a tapered thread but not as much as pipe thread. Again, the paste is what we use.
                  That looks like the same thread that is used on the gagues of a Sulzer compressor, it is a metal to metal thread & seal.

                  Comment


                  • #10
                    Re: Thread Jointing compound or PTFE at JIC and NPP threads etc

                    it is British pipe thread. it is straight and seals on the bottom on a small sealing washer.the only reason I know this is that I ran into it a few years ago and like to went crazy and the people at royal brass put me on the right track they are in knoxville tennessee

                    Comment


                    • #11
                      Re: Thread Jointing compound or PTFE at JIC and NPP threads etc

                      Originally posted by cowboy View Post
                      it is British pipe thread. it is straight and seals on the bottom on a small sealing washer.the only reason I know this is that I ran into it a few years ago and like to went crazy and the people at royal brass put me on the right track they are in knoxville tennessee
                      tell me about it once i ran into a hybrid jis(japanese fitting)/jic had a japanese flare and jic threads....we ended up replacing a 20,000$ fixture due to this off spec component

                      Comment


                      • #12
                        Re: Thread Jointing compound or PTFE at JIC and NPP threads etc

                        Cowboy has it spot-on. Got to to the bottom of it. It is a BSP gauge fitting. Uses a 4-5mm diam. copper crush washer. Common here, and must be the Brit way if it has some of you head-scratching.

                        I have found a PTFE tape made especially for gas threads. Usually yellow but now use high-pressure pipe-thread paste [La-Co Slic-tite works where PTFE fails]. Thanks gents.
                        BritCNGUser
                        Senior Member
                        Last edited by BritCNGUser; 05-16-2015, 04:33 AM.

                        Comment


                        • #13
                          Thread revival. It's been a while. I've been using La-co thread sealant paste, and frankly it's not always worked for me. It's a PTFE paste, and I've dropped the La-co, and started using gas-grade PTFE tape with more success. In the UK we're sold PTFE tape in gas-grade (yellow reels - white tape) and plumber/water-grade (white reels - white tape). I'm not sure what the difference is, the gas-grade is supposed to be thicker, and could be a different chemical composition. I've searched for a definitive answer, only to find heaps of conjecture and ever more layers of BS, I've no clear answer.

                          Now I look for an anaerobic sealant. I understand the hydraulics industry use one of the Loctites, only there's a heap of variants. And those suited to methane/natural gas applications seem to meet only low-pressure domestic-gas requirements. I'll report back.
                          BritCNGUser
                          Senior Member
                          Last edited by BritCNGUser; 3 weeks ago.

                          Comment


                          • #14
                            This looks like the newest H.D. pipe sealant, never tried it but the pressure ratings are considerably higher then the stuff I was using back in 2012, I've since used Rectorseal with good success, when I run out ill give this Megaloc a try.

                            https://youtu.be/mhhyvXfcYWM

                            Available in jars or small tubes,
                            https://www.supplyhouse.com/Hercules...AaAuEdEALw_wcB

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