Yellow PTFE tape (aka Teflon) is supposed to be used for sealing gas pipe thread, and white PTFE tape, for water. But is there really any difference between them? I had always thought that yellow was specially formulated to resist methane and other natural gas additives, but an HVAC tech told me the different colors are just markers, so that anyone looking at a pipe can immediately tell if it's gas or water. Other than their colors, they're just the same. Was he correct?
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The yellow tape is heavier.– Paul LoganCommented Nov 23, 2017 at 0:21
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@PaulLogan, but other than that, they're the same (iow, PTFE is PTFE, not additives)?– BillDOeCommented Nov 23, 2017 at 0:28
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I read SOMEWHERE, that SOMEONE said, yellow tape is non petroleum based and should be used for oxygen hose connectors for welding and cutting oxygen tanks. We must not use white one, because it is petroleum based, and oxygen plus petrol, gasoline, oil makes explosion. But this is not verified yet. Still searching to find a proper proof for this claim. However, to be on the safe side, for my welding hose stuff i use yellow teflon tape.– Alex MarkovCommented Sep 25, 2020 at 5:00
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7 Answers
I know from handling it that it is clearly heavier. One or two wraps would be equivalent to to six or eight of the white stuff. It is rated for slightly lower temperature. *** After some minor research, evidently there are differences, however, as I see it, these differences are way beyond the scope of the common everyday amateur or even most professionals, i.e. the yellow stuff is rated for 10,000 Lbs. It is considered double density. The white is considered single density. There evidently is a red type also, that is triple density. The red tape is for large diameter pipe, 2" and above. (I've never seen that). The white is rated for something less than 10,000-Lbs. The yellow is rated for +500°F. The white is rated for +450°F. Are you getting my drift.
If I could add a side note; after running several miles of gas pipe in my time, I never used TFE tape on my joints exclusively. I would always use a pipe joint compound/paste type product, Rectorseal was my go-to choice. One day I was in the process of installing one of my gas pipe jobs. It just happened that the local gas supplier tech showed and was checking on something. They supply gas to thousands of homes in our area. He noticed that I was using Rectorseal. He made a point to come over and thank me for using this product. He said that if all the contractors in the area used this product, his job would be a lot easier. So after all this talk about TFE tape, I wouldn't recommend it. It doesn't seal as well as a good quality joint compound.
answered Nov 23, 2017 at 9:38
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1The company that services our house used both PTFE tape and dope (the blue stuff). And fwiw, -450°F is near absolute zero, -500 well below.– BillDOeCommented Nov 23, 2017 at 19:40
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Another benefit to pipe dope versus tape is that there is the potential for sliced-off/torn pieces of tape (caused by carelessly wrapping the tape over the end of the threads a bit) to be carried downstream where they could cause clogging issues. Commented Nov 23, 2017 at 20:02
The colors mean something, but the meaning has changed over the years so some info may be old. The CURRENT standard is:
White = single density tape and is ONLY good for small fittings up to 3/8 in. pipe. Most people are unaware of this. "Double Density" tape used to come in white as well, but because that could be used for larger pipes, it was impossible for inspectors to know if the white tape used on 1/2" and larger pipe was in fact double density, so they stopped making it.
Yellow = double density, required for natural gas (methane) piping 1/2" to 2" dia. pipe. In many jurisdictions you MUST use double density tape on gas piping, so inspectors will look for yellow.
Pink = triple density, required for NPT threads 1/2" to 2". Again, most people are unaware of this change and hardware stores rarely sell it for the DIY market, but if you are going to get an inspection, this is what you must use now. This is also good for gasoline and propane lines.
There is also green for medical gasses (oil free tape) and gray / silver for use with stainless steel and aluminum pipe (has anti-seizing compounds embedded in the tape).
Over 2" you must use sealing compounds.
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Can you clarify whether there's a difference in what the pipe is carrying or only if it's pipe diameter that indicates what color tape to use? Both water and combustible gasses could be carried by a 3/8" pipe - can/should white tape be used in either case? If I have a threaded fitting on a 1" water supply line, do I use yellow (it's in the 1/2 - 2" range), or do I use yellow? Lots of questions left from your answer...– FreeManCommented Sep 25, 2020 at 12:22
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You can't use the tape color to determine what's in a pipe, if that's what you mean. Yellow double density tape is required for gas, but that does not preclude you from using it on water. 3/8 NPT pipe is rarely used on gas because at that small of volume, people tend to use tubing, which does not need tape. But I suppose if you did use 3/8 for gas, you would need to use yellow.– JRaefCommented Sep 25, 2020 at 22:46
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My question wasn't about identifying the pipe's contents by the color of thread tape, but if the tape color (type) is determined only by pipe diameter (which is sort-of how I read your post), or if the color is determined more by the contents - i.e. use white on pipe up to 3/8" no matter what is running through the pipe, use yellow on 1/2-2", no matter what is running through the pipe, etc. Or, use white for water up to 3/8", yellow from 1/2-2", etc, but use yellow for any flammable gas, no matter the pipe size, etc.– FreeManCommented Sep 26, 2020 at 16:19
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I thought NPT fittings were made worse by the addition of tape because the sealing surface is the threads themselves and you want the metal on metal contact?– BradCommented Feb 4, 2022 at 3:08
Yellow is now my preferred choice to use with pvc and metal water pipes. I was forced to use it over traditional pink or white tapes not being stocked. It's cost more but requires less layers and is a lot less fussy. Never had any problems.
Standard Ptfe tspe should not be used on oxygen lines. There is a green ptfe tape made specifically for this. If you have ever disassembled a ptfe joint you would know that the tape is smashed and stretched in the joint spaces until it does not resemble tape. I have found that the white tape actually flows into the spaces better than the yellow tape creating a better seal. A plumber told me that he uses white ptfe tape and Rectorseal#5 on every joint and never has a leak. I adopted this technique 20 years ago and can report that he is correct. The plumbing code makes no reference to which color tape to use other than it must be an approved type. Yellow ptfe tape is merely thick than white. They are both made of the same material. I have also noticed that it is more difficult to wrap the wellow tape on pipe thread and get it to stay. You have to stretch it more which also makes it thinner. Use whatever you want but rest assured white ptfe is approved for gas and other flammable liquids as a thread sealant.
like many products they become commodities and it gets down to price, when PTFE tape was introduced to replace hemp as a thread sealant it was very successful and it became a race to the bottom trying to sell the small spools. PTFE thread seal tape became narrower the commonly used 1/2" became 12MM often shorter from 12 metres to 10 metres and became thinner so the product became very poor, because people were only looking at price per spool. Then someone with a good marketing focus decided enough of the rubbish let's offer the old style thickness and colour it yellow and market it as gas tape with a dearer price for a quality product. People appreciate the better quality and now pay more for it. Basically you get what you pay for.
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Do you have anything to back up these claims that "the product became very poor"? I've used white tape on all my water fittings and never had any issues with the product itself. Any proof that the thicker yellow tape is just a marketing gimmick? There are two answers claiming that there are very specific reasons for them being different thicknesses, not just marketing.– FreeManCommented Feb 4, 2022 at 13:23
If you use white tape on petroleum lines it will fail in a few hours or days. I know this to be true. If diesel, you will get air leaks into your lines as the lift pump pulls the fuel from the tank, causing the expected issues. If gasoline, the joint will weep fuel.
Yellow is impervious to diesel, gasoline, oil, and other petroleum products, so I would assume, but do not know, that Propane and natural gas will cause white tape to also fail.
one thing that no one ever mentions is that using too much tape can break a fitting....so the yellow tape since its thicker probably should use less .....Ive broken fittings at times probably because I screwed it too far in and maybe because the tape was wrapped too many times.....if its not screwed in far enough it may leak and if its screwed too far it could break the fitting depending on the material....thats why dope may be better than tape it probably doesnt make the fitting very tight like the tape would but makes a good seal
