Best way to seal u-bend in waste?

martin57

Hi folks,

Hope everyone is keeping well in the big freeze-up. I just noticed this morning that the water wasn't draining away from the sink in the upstairs bathroom. Just checked that it wasn't dirt, but it seems the white plastic waste pipe is frozen somewhere down the waste pipe. It's definitely not at the first u-bend that hooks into the sink as I undid that.

When I screwed the plastic bolt on the u-bend off there seemed to be a white stringy stuff in there that the plumber obviously used to seal the join where the plastic bolt screws onto the sink. Whats the name of this I wonder as I have never seen it before, and when I want to seal it again whats the best thing to use to prevent any minor leaks, I think silicon probably wouldn't be a great idea to put inside the plastic bolt as it would totally make the bolt un-screwable again.

Thanks very much for any help and a happy xmas to everyone.
martin57

Browntoa

this is the stuff they used

http://www.diytools.co.uk/diy/Main/sp-75-3444-29334-draper-12m-ptfe-plumbing-tape-roll.asp

although should not be needed

olias

ptfe tape

http://www.screwfix.com/prods/51030/Plumbing/Plumbing-Accessories/No-Nonsense-PTFE-Tape-Pack-of-10?cm_mmc=GoogleBase-_-Datafeed-_-Plumbing-_-No%20Nonsense%20PTFE%20Tape%20Pack%20of%2010

Olias

jrrowleyws

It's PTFE tape, very cheap from a DIY shop. Generally plastic fittings shouldnt need it though. If it leaks without it then buy some, put a few turns onto the thread (might take a few practises to get it right) and then screw it up, should sort the problem.

Mustard_Dave

There shouldn't be anything on the connection other than the rubber seal on the trap (see photo).



It sounds like somebody has used PTFE tape which is intended for sealing threads, such as where a valve screws into a radiator. The plastic nut is to secure the rubber seal tight against the bottom of the waste fitting. It sounds like somebody has bodged it in the past.

Clean the bottom of the waste fitting and the trap, check the black sealing ring is still present and is not torn. Also check the thread is in good condition. When you put it back, make sure everything is straight and that the pipe work isn't pushing the trap sideways. You shouldn't be putting anything else on it to seal it - certainly not silicone or PTFE tape.

ormus

make the join is square. and get a new sealing ring if required.
you shouldnt require any ptfe tape.

Inactive

jrrowleyws wrote: »

It's PTFE tape, very cheap from a DIY shop. Generally plastic fittings shouldnt need it though. If it leaks without it then buy some, put a few turns onto the thread (might take a few practises to get it right) and then screw it up, should sort the problem.

It seems that is why the PTFE Tape was used in the first place.:D

John_the_Boy

As mentioned above you shouldn't need PFE to seal the joint.

A alternative to PFE (costs more about £4 a tube but I think is worth it) if you really need it is Fernox LS-X, never without a tube and has got me out of a few leaky situations - lol.

https://www.fernox.com/files/Fernox/Content/PDF/English/LS-X.pdf

27col

I find that the problem with Fernox LS-X is that it goes off in the neck of the tube, even if you have put a nail or some such in the open end. Not a problem for a professional plumber who uses it regularly. In any event plastic waste systems do not really need anything as long as the nuts are well done up. If one leaks it is usually only needing to be given another slight twist by hand.

tony6403

you can buy a new trap for two or three quid.

latecomer

if its not sealing i'd get a replacement trap as above. i've never used or seen PTFE used on waste pipes.