You want Liquid PTFE. I believe Loctite make it. You will need to turn the water off for a few hours to let it cure, but it is designed for this kind of sealing.
Screwfix part no 12693, costs a fiver. I have an earlier version and it is good on plastic fittings subject to vibration (like shower pumps). However as the other posters suggest it might be wise to look for the root cause (especially as you have isolation valves).
The reason I ask is that I have got a joint in my new shower that I cannot get water tight.
There is plenty of PTFE tape on the thread but water slowly seeps through.
Is there a product that I can smear round the joint, without breaking it, that would seal it.
I can isolate the water as I had the foresight to put isolation valves on
For instance, and don't laugh at me
Superglue, No Nails, instant gasket.
Or even silcone sealant, as I have a fesh tube of that
Any help would be gladly welcome as I'm looking a burke to the misses .
Thanks in advance
Forget external sealing methods - break the joint and apply liberal amounts of boss white or similar jointing compound- remake the joint and water seep should cease. Regards Pete
Which is basically silicone sealant (without the fungicide that most sanitary silicones have). Use the silicone that you have to hand if the joint is on the inlet to the shower, between your incoming pipework and the inlet of the shower. (Pedantically, you shouldn't need to and you should find out how to make the joint properly, but if the silicone doesn't work you can always peel it off again and do the job properly.)
As you have no idea what type of silicone he has,how can you advise him to use a product that is not intended for the purpose of sealing water joints,and will almost definately breakdown in a short period,maybe not a disaster in a shower but in a bath or sink tap connecter,well thats asking for trouble big time.
In theory you should not need PTFE on compression joints, but it saves all the hassle of having to redo the joint when the cooling and heating cycle has slightly loosened it.
No it isn't its more like superglue. Its got me out of serious problems more than once. In one case a header tank for 6 flats was seeping around the outlet. A smear of that and its been fine ever since, and that was 8 years ago.
In domestic water plumbing, fairly little - compared to a field like compressed air. Tape is used for a tapered threaded connection, where there is a compressive force across the thread.
In a "compression" joint the seal is a knife-edge seal into a ductile metal (olive to pipe) and a coned compression joint in metal (olive to fitting). Neither of these will benefit from tape and for the knife edge it would be a disaster and almost guaranteed to leak. _If_ the seat or the olive are already chewed up, then a soft tape or hemp filler might make the leak less bad than bare metal, but the real fix is to replace the chewed components and give a smooth seat, not to bodge it. A compression joint also has a nut and you can apply sealants to that where you like - although they're not going to leak anyway.
In a parallel threaded joint, then it's a bad idea to try and seal on the threads. You can only do this with an adhesive compound, not just PTFE, and that makes the joint hard to dismantle in the future. You should use the face seal washer intended. If you don't have a washer, then use Plumber's Mait and hemp fibres - it'll work better than PTFE, for a large gap with a small compression load.
You may also use PTFE tape as an anti-seize measure on some fittings or threads, but don't do this on the fitting to olive seal of a compression joint or you might cause more leaks than you're trying to avoid.
If you _do_ have a leak somewhere, then an Oyltite stick will serve you better as a bung than trying to get PTFE to seal it.
The Fernox LSX they have on my planet is so similar to clear silicone sealant that it if it didn't say Fernox LSX on the expensive little tube I wouldn't know the difference. It's also quite different to Earth superglue - if I were being uncharitable I'd suggest putting a bit of each on your fingers (or maybe keyboard) and seeing how similar they are :-)
The OP said he had silicone sealant. All the silicone sealant I've come across (though I admit I'm not an expert on the stuff) is waterproof when set and stands up to water at temperatures less than superheat pretty well. I've never come across any that breaks down in water.
In a "compression" joint the seal is a knife-edge seal into a ductile metal (olive to pipe) and a coned compression joint in metal (olive to fitting). Neither of these will benefit from tape and for the knife edge it would be a disaster and almost guaranteed to leak.
Agreed on the olive, but vital on the thread. Olives don't always seal perfectly with the best will in the world and PTFE on the threads acts as a backup.
I work with hydralic fittings all day, up to 250 bar water pressure and I've heard the "you shouldn't need PTFE" argument over & over.
Any threaded connection, olive or not, benifits from PTFE - which is far superior to any jointing compound.
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