P.T.F.E. TAPE is it a lube or filler?


Old 10-18-18, 02:04 AM
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P.T.F.E. TAPE is it a lube or filler?

This is a debate I've never got to bottom of. Some tech departments from manufacturers say its for filling some say its only a lubricant to allow deeper tapered threaded jointing. So, can anyone finally tell me which is it? Been a plumber for 35 years.
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Old 10-18-18, 05:00 AM
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Not a plumber, but always been my belief it was a little of both. It is certainly a lubricant or at least acts like one. There are some applications where you are instructed specifically NOT to use the tape because the lowered friction can cause over-tightening of the fitting. Let's see what the plumbers say.
Old 10-18-18, 07:52 AM
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Thanks for that. As far as filler goes, not really, ptfe having a very low coefficient of friction (very good lubricant) has virtually no "memory" so is liable to suffer from "creep" which is not a good idea when using as a compressed thread filler. So what are your thoughts on that?
Old 10-19-18, 09:52 AM
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Not a plumber either, but Iíve seen this question many times on this forum and other places. I thought at one time I found a really good answer from a guy who was an engineer or scientist from one of the manufacturers and I thought I saved it. But looks like I lost it. I think he said it was both a lubricant and filler and went into some detail.

But Ö just looked at Wikipedia (link below) which also describes it as both a lubricant and filler, however, it looks like the article is kind of labeled unreliable. Back to square one Ė lol!

It seems to me that it would have to be a filler (in addition to a lubricant) because the tape doesnít just disappear. There must be female threads, tape, and male threads sort of producing a tape sandwich (LOL) which has to resist water flow at substantial pressure. Unless, however, somehow when you tighten the threads together the tape slips upwards and does not become part of the watertight mating surfaces. But that seems hard to visualize.

However, thatís only my intuition which most certainly may be wrong. Seems funny that a question that seems so simple does not seem to have been definitively answered. I know that an awful lot of smart people say itís only a lubricant.

Old 10-20-18, 04:02 AM
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Originally, it's a lubricant. However, if enough of it is used it can also seal" iffy" connections. Many of the China made fitting are not high quality and will not be manufactured to specs. Using extra tape will help seal a joint.
Note, that TFE for gas lines is yellow in color and is of a different make up from the plumbing type. That should tell you something. Like ,maybe the tape is not perfect for a seal. The yellow gas tape is made not to deteriorate with contact to natural gas. Hmm...
Old 10-22-18, 07:28 AM
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As long as water does not come out I could care less. I find both the paste and tape seem to prevent water from leaking through the threads so I don't spend much time on getting to the bottom of exactly how they do it. Most times I use both but if I find myself with only one or the other, I don't worry much about it. They both work.
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