Teflon tape on pipe threading

caoimhe_kelly · 17-02-2025 03:30PM #1

I'm installing an undersink water filter and it says to add teflon tape to the threading on the pipes in certain steps… See 1min 43 seconds in the youTube instructions…

https://youtu.be/IcI-P_F4r6Q?t=105

Is this necessary ? and if so what purpose does it serve? Thanks

10-10-20 · 17-02-2025 04:25PM

https://www.boards.ie/discussion/2058396926/teflon-tape-on-pipe-threading

Telfon (PTFE tape) is the most critical of plumbing substances. It forms a seal on the olive or joint and won't bind/stick to the surfaces under pressure as it's inert. It's as cheap as chips too - around 3 EUR for a roll.

Have a look at the application methods on YouTube as there is a right and a wrong way.

carveone · 17-02-2025 04:47PM

Teflon is usually necessary on threaded connections. For example the tail into a radiator better have teflon or it absolutely will leak. Compression fittings usually don't need it (assuming they are clean) as the olive on the pipe seals against the sloping face on the connector*

Note the direction of taping - at 1:43, the tape is being wound clockwise looking from the top. At 1:52 the connector is being wound on clockwise as well, same direction as the flow of the tape. If you do it backwards, the seal will bunch up and you'll get a leak.

*Aside - the tape would go around the olive. If you see anyone winding it around the threads, sigh loudly and roll your eyes 🙂

caoimhe_kelly · 17-02-2025 04:53PM

https://www.boards.ie/discussion/comment/123181377#Comment_123181377

https://www.boards.ie/discussion/comment/123181465#Comment_123181465

Thank you very much folks

caoimhe_kelly · 19-02-2025 08:01PM

https://www.boards.ie/discussion/comment/123181377#Comment_123181377

https://www.boards.ie/discussion/comment/123181465#Comment_123181465

Right folks. I went at this this evening and failed! When I turn back on the water for the main kitchen tap there is a very slow leak at the connection that's fitted at 2:04 in the video and also a slow leak a the connection that leads to the kitchen tap. Any advice for me?

I applied the teflon tape in the right direction.

The connections are very hard to get to....so wondering is it a case of me not getting the right leverage to tighten them

Water to the tap has been turned off for the night

10-10-20 · 19-02-2025 09:30PM

Hi, in fairness it might need 5 or 6 wraps of PTFE, and we didn't tell you that.

Question... is it leaking at the water feed adapter part where it fits onto the existing piping?

If that's where then you might be hitting an issue with UK plumbing being a wider diameter that Irish plumbing. Sometimes that can be resolved with an Irish spec adapter, but other times it just needs to tightened up with yet more wraps of PTFE.

More info here...

https://www.thetapshop.ie/irish-copper-pipe-vs-metric-copper-pipe/

caoimhe_kelly · 19-02-2025 09:42PM

https://www.boards.ie/discussion/comment/123189448#Comment_123189448

Thanks. It's leaking at the water feed adaptor part. I don't think the diameter is an issue so I'll just try more PTFE tomorrow

10-10-20 · 19-02-2025 10:15PM

https://www.boards.ie/discussion/comment/123189513#Comment_123189513

More PTFE it is then! As it's the incoming mains, it's under a lot of pressure. You need to get it sealed so that it's not weeping and a concern in the future. 👍️

caoimhe_kelly · 20-02-2025 05:06PM

https://www.boards.ie/discussion/comment/123189669#Comment_123189669

I've one weeping leak sorted but struggling with this one. Here is the connection after I take it off...

Does that look ok? I wrapped it 5 times (clockwise rotations) before fitting it

Edit: my PTFE tape is 0.076mm in thickness

con747 · 20-02-2025 05:26PM

https://www.boards.ie/discussion/comment/123192141#Comment_123192141

Not much tape on the first threads there, use more tape! No need to tape the nut at the end just the threads. Wrap it tightly as well not loosely.

caoimhe_kelly · 20-02-2025 05:31PM

https://www.boards.ie/discussion/comment/123192202#Comment_123192202

I thought the first 1 or 2 threads should be left clean?

con747 · 20-02-2025 05:32PM

https://www.boards.ie/discussion/comment/123192213#Comment_123192213

No, tape all the way but not over the edge, well that's how I do it but others might say otherwise.

pjdarcy · 20-02-2025 05:37PM

Add more tape on these threads

pjdarcy · 20-02-2025 05:39PM

Remove this tape as it's not doing anything

cute geoge · 20-02-2025 05:46PM

My plumber used roll on about 10 turns of the tread at least ,never any leak

caoimhe_kelly · 20-02-2025 05:48PM

It's all good now. I wrapped it about 13 or 14 times. It was harder to screw in.. particularly at the end so a much better seal i'd say

Thanks for all the help folks!! Really really appreciate it!

GreeBo · 20-02-2025 05:52PM

https://www.boards.ie/discussion/comment/123192215#Comment_123192215

Tape the whole thing, then spend ages trying to peel it back off the edge, eventually stretching it so it completely blocks the valve, curse loudly, then poke it with your finger and peel it back.

Thats how my grandad and my dad did it and by god thats how I do it now.

The Continental Op · 20-02-2025 05:58PM

I sometimes twist the PTFE tape to make it into string and use that the fill the threads before using the PTFE tape flat to cover the threads at least 5 times.

Another old trick that some plumbers still like is to rough up the threads with a file so they grip the tape better but thats really a throw back to the old hemp and jointing compound days.

Teflon tape on pipe threading

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