Leaking joint?

Question

I am trying to install a mains water filter. This has a 3/4'' female threaded inlet and outlet to which I am attaching threaded male brass connectors. The problem is that it is still weeping slightly despite use of quite a lot of ptfe tape. I have dismantled, re-assembled and replaced the ptfe tape about half a dozen times but I can't seem to stop the weep. The filter is plastic (tho' it seems to be very good quality -or that is very expensive anyway) so I am a little worried that if i tighten too much it might crack. I have no problem with the brass-to-brass reducer that attaches to the brass connector, so I don't see what I am doing wrong. The supplier says ptfe tape should work (I asked if a rubber or fibre washer would help)....any ideas? is there a sealant I could get maybe? Thanks

(....some people seem to have nothing better to do than write dumb responses -referring to the first two anwers- ..why bother?)

Answer 1

first ensure the fitting's threads are not now damaged or x-threaded and that the thread is the same type, should be standard for plumbing fittings, bsp in the uk.
also check there are no cracks in the plastic, difficult i know, look carefully at where the leak comes from, inside or outside the insertion into the fitting.

as suggested 10+wraps of ptfe tape.
alternatives are
ptfe thread, like thin string, from loctite at plumbers merchants, one or two thicknesses around the threads i.e. not much.
wrap in the direction the fitting turns onto the plastic thread
use slightly less at the start of the thread so the fitting can wind on without cross threading.
liquid ptfe sealant for pipe fittings also loctite i seem to remember, not threadlock etc but for pipefittings so disassemblable.

DO NOT use liquid pipe sealant/paste it is not to be in contact with plastics.
well done those who dont really know what they are doing for the last suggestion

Answer 2

Try using the paste the plumbers use. (Pipe joint compound) It is applied with a little dobber in the can and should take care of the leak. Remove the teflon tape as best you can. You don't want to use a sealant that welds or solders the joint together so you can't change the filter later Tighten as much as you can and a small one at the end. I enjoy reading and answering some questions but annoyed with some stupid responses. Why do these people waste their time online.

Answer 3

LSX leak sealent always works for me. I'm sure it's compatible wit plastic threads too. Get it from most plumbers merchants. It's by no means cheap but it's ALWAYS done the job for me. It's a small tube inside a blue box wit multi-coloured writing on it if i remember correctly. Gotta b worth a try if ptfe has failed.

Answer 4

There are several types of sealant on the market that will help (possibly), a good teflon based sealant should do the trick. I use it all the time on stubborn leaks. Just do not get any ahead of the threads so that it is pushed into the filter.

Answer 5

most times PTFE will do the trick, make sure you are putting it on in the direction of the tread, so when you screw it in it does not unravel, and don't put to much on. and push it into the threads . gas PTFE is a thicker tape, might be worth a try.

as you said you need to be careful with the plastic thread, you cain't put a lot of pressure on it.
there are some anaerobic sealants you can use, but they normally need to cure first .http://www.bearingshopuk.co.uk/index.asp?function=DISPLAYCAT&catid=173&kw=loctite&fl=109133&gclid=CJCr-d3W_48CFQRgMAodHCyGpQ

Answer 6

10 or 25 wraps? You wouldn't be able to thred the fittings together! Plumbers use two or three wraps, maybe one or two extra if you have a leak. I suspect you may have bad threads on one or both fittings. I just spent three hours on what should hsve been a half hour job replacing a pop-up assembly. The threads on the tailpiece were bad.

Answer 7

You need to insure there is a taper to the threads of the pipe. If there is no taper all the Teflon tape in the world will not help. You should be able to re-thread the pipe if needed. The taper is actually what seals the pipe. Check out the link below. Hope it helps.

Answer 8

if you are using a paste/jointing compond,you need to make sure it is water potable,insert a 3/4 fibre washer into female iron,wrap around at least 25 wraps of ptfe.make sure when you wrap the tape it is going to tighten into the female.

Answer 9

You can purchase pipe dope compound at Home Centers or hardware stores. I prefer Rector-seal products. They are certified for all liquid uses and gas.

Answer 10

Yes there is. It will be in the plumbing section of most hardware stores. It is usually used when fitting pipes of all kinds.