Leaking thread couplings, how tight?

[FiscoKing]

Hi,

I've got a thermostatic shower mixer (in wall). See pic:

http://i67.photobucket.com/albums/h316/goodproducts101/Dsc00252.jpg

It leaks from the junctions indicated on the picture.

There are threaded reducers that came with the mixer (? to 15mm) and I added a few turns of ptfe before screwing them in (no olive). I tried tightening them up, but the leak just gets worse.

I assume there is some unwritten rule when screwing these things together, like with compression joints (quarter turn past firm).

Given that the reducers are almost all the way in (and still leaking), are they now damaged (like compression fittings), or can they be reused with some more ptfe?

One last question. If I have to disassemble the pipes form the mixer, can the compression fittings & olives be re-used (another quarter turn past tight), or do i have to cut a new section of pipe?



Thanks,

 

[Rob]

A few turns of PTFE is not enough. Put on loads! Unfortunatley you will have to completly remove and start again

 

[gas4you]

You could try using loctite 55. Excellent thread sealing product

 

[Soggy_weetabix]

Hemp

But as I understand its outlawed now?

David

 

[FiscoKing]

Thanks guys.

What about the compression olives ?

Can I leave in situ and just re-tighten?

 

[gas4you]

I would undo them and use a jointing compound on them such as jet blue from Plumb Center. Other good makes are available

Over tightening can cause more leaks than not tight enough

 

[Rob]

I always prefer PTFE on water joints.

 

[gas4you]

I know its just as good Rob, but one of my pet hates is seeing it around the joint afterwards

 

[Rob]

I know its just as good Rob, but one of my pet hates is seeing it around the joint afterwards

Yeah looks rubbish on brass fittings especially!

 

[FiscoKing]

UPDATE:

I used loctite 572 in the end (avail from screwfix).

It's a liquid and you just apply it to the male thread, screw in as far as the coupling will go and leave for 24 hrs (on brass). 72 hrs for steel.

Worked a treat.

I did consider loctite 55 cord which is trumpeted by many pro plumbers, but if you look at the pdf on loctites website, they still recommend that you roughen up the male thread prior to applying the cord to stop it being pushed off. You also have to apply the chord in a fashion, and not put too much on or too little.

This had echoes of the ptfe problem for me. So I suck with loctite 572. No need to roughen up the thread and any excess liquid can be wiped off after it's been screwed in.

DIYproof.

Also, I just left the existing 15mm copper olives in situ, and added another quarter turn past firm to seal on reassembly (I think this worked because the original compression joints had not been overtightened).

 

[HarrogateGas]

UPDATE:

I used loctite 572 in the end (avail from screwfix).

It's a liquid and you just apply it to the male thread, screw in as far as the coupling will go and leave for 24 hrs (on brass). 72 hrs for steel.

Worked a treat.

I did consider loctite 55 cord which is trumpeted by many pro plumbers, but if you look at the pdf on loctites website, they still recommend that you roughen up the male thread prior to applying the cord to stop it being pushed off. You also have to apply the chord in a fashion, and not put too much on or too little.

This had echoes of the ptfe problem for me. So I suck with loctite 572. No need to roughen up the thread and any excess liquid can be wiped off after it's been screwed in.

DIYproof.

Also, I just left the existing 15mm copper olives in situ, and added another quarter turn past firm to seal on reassembly (I think this worked because the original compression joints had not been overtightened).

Thats fine using loctite untill you come to needing to undo the joint!!

Rob does what I do.....PTFE every time.