Perpetually leaking tap unions - help!

[iep]

Hi, I'm just finishing the installation of my new bathroom. All was been going great until I got to the seemingly simple task of screwing the isolation valves into the 1/2" bsp wall plate elbows.

I'd expected this to be the usual deal (wrap thread in PTFE and screw into wall plate elbow). Despite many attempts though, and increasing quantities of PTFE, I can't get a decent seal and the joints continue to weep. I've tried normal PTFE tape and the Loctite 55 'string' I've even tried using them together (which almost worked).

Can anyone suggest what might be going wrong and if there is another magical product out there which might get me out of this mess?

FYI, I'm a DIYer but have done a lot of plumbing and must have managed 100s of similar PTFE 1/2" BSP joints in the past with no problems at all.

Thanks,

iep

 

[bellairaphon]

Try putting a 1/2" fibre washer into the backplate.

Nath

 

[iep]

Thanks, I did try that but unfortunately, no joy.

Also, when I did try that, the isolation valve (a 90 degree one) ended up pointing down rather than up when fully screwed in tight against the washer.

Cheers,

Ivan

 

[jeds]

Try Fernox LS-X from Screwfix or B&Q. Never known it fail on the odd problem joint.

 

[iep]

Sounds promising. Can you advise on how to use it? Do you apply in on it's own or in combination with PTFE/Loctite 55?

Thanks,

iep

 

[jeds]

I would put a thin smear of Fernox on the thread plus three or four wraps of ptfe and then another slightly thicker smear of Fernox. The ptfe is really just to give you some thickness to get the valve the right way up. Technically I think it recommends you leave the joint for a certain length of time before pressurising but I've never know it not work immediately.

 

[Nige F]

Hemp and the fernox LSX if all else fails and the Water Gestapo don't find out

 

[Gasguru]

Surely the isolating valves have a compression fitting on each end. Use a 1/2 MI to copper coupling. The thread will be longer and enable you to wind the PTFE on to form a taper.

 

[iep]

Sadly not, these are chromed fancy external isolation valves with 1/2" bsp male in and out. As ever, get fancy, get f**ked.

iep

 

[Nige F]

clean the chrome off the threads with a hacksaw blade

 

[iep]

Interesting, does that help with the seal somehow?

Cheers,

iep

 

[Madrab]

Unusual, usually the issue is mixing the thread types that causes the major issues with sealing, taper and parallel, metric/imperial - i.e. a metric male compression end fitting into a 1/2" bsp female.

Who are the suppliers of the shower and ISO valves, are they all part of the fitting kit?

If you use Gas PTFE you may get on a bit better, it's 40% thicker.

 

[geraldthehamster]

Try using gas PTFE tape. It's thicker. I had a perpetual problem with a bib tap leaking where it screwed into the upstand, and gas PTFE fixed it straight away.

Cheers
Richard

 

[iep]

Ta, Fermox and Loctite 55 seem to have worked. I'll try the gas tape if leak returns.

The fittings are not part of a single kit. actually I am using them as outlets through a bulkhead to hook up the sink and toilet. FYI, wall mounted fitting looks like this (armitage shanks):

And isolation valve is made by another manufacturer but fearures a 1/2" basp male thread. I'd have thought 1/2" bsp male to 1/2" bsp female should just work.

Final result looks like this:

Cheers,

iep

 

[Nige F]

Nice result