Tip to secure kitchen sink waste right below sink to trap

28 Nov 2010
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United Kingdom
It's the first connection under the kitchen sink which had gone very loose and was of course leaking. A grey plastic B&Q waste/plug etc joint by white nut from the waste trap/bend. The plastic nut just about tightened but went loose, however it went tight enough to seal again I suspect it will be ok for a while however I can see it loosening off after a number of kitchen sinks are emptied!

I don't actually know if it's the threads on the grey B&Q sink part or the plastic nut on the top of the trap at fault. Threads looked ok to me on the grey plastic though

Is there anything I could try to get the plastic nut to stay fixed so as it doesn't loosen off in time(being tight enough just now) i.e. a thread lock of some sort or silicon? I feel it just might not be necessary in the meantime to start replacing one or both-especially not knowing which is at fault, plus the grey sink part is well siliconed on to the stainless steel sink etc

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Some of those cheap pastic fittings do jump on the thread just as you're getting them reasonably well nipped up, even by hand.
They're a nuisance but as tincup said a good few wraps of ptfe wound tightly round the thread should help it to hold.
Though replacing both would be the best option.
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Thanks for replies

I should have said I actually did wrap a wee bit ptfe tape round it. Maybe should've used a little more, I didn't have much left on the roll- I might actually try that again, as you say it might just do it

Not sure if there was a rubber ring on the nut. Certainly seals where the trap went onto waste, but dunno about the nut itself- I didn't really know there was another there
If you undo the nut there should be a lip on the pipe inside it, with a thin rubber seal.
You need about ten or so wraps of ptfe tightly wound round the thread in the same direction as the nut tightens to have a chance of it not jumping.
I think the rubber washer probably was there but i'll need to check when I look at it again

MANY THANKS for such helpful replies
make sure the rubber sealing washer isn't twisted as this can sometimes happen if it's an older trap and doesn't sit square on the lip..

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