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?

  • The yellow tape is heavier. – Paul Logan Nov 23 '17 at 0:21
  • @PaulLogan, but other than that, they're the same (iow, PTFE is PTFE, not additives)? – BillDOe Nov 23 '17 at 0:28
  • 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 Markov Sep 25 '20 at 5:00

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.

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    The 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. – BillDOe Nov 23 '17 at 19:40
  • 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. – Jimmy Fix-it Nov 23 '17 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.

  • 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... – FreeMan Sep 25 '20 at 12:22
  • 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. – JRaef Sep 25 '20 at 22:46
  • 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. – FreeMan Sep 26 '20 at 16:19

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.

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