Having just run in a new 32mm plastic water main I ended it with one of the Plasson plastic stop cocks.


Plasson stopcock


I've done the nuts up as tight as I can by hand (and then with pump pliers) and it keeps weaping.

If there any reason I can't use PTFE on it? Or should I try something else?

Thanks,
James

You shouldn't need PTFE and I've fitted hundreds of fittings with nothing more than a 'nnnng!' by hand. These fitting don't like to seal on pipe that is scratched so just check the ends of the plaggy pipe. If it's damaged and you can't cut it back to a good bit, try wire wool, sandpaper, or whatever else you have close by. Unless you have a dog close by. Don't use a dog.
There's nothing wrong with using PTFE but you shouldn't need it!

ETA; it is possible to overtighten these fittings! Pump-pliers can squash the fittings so proceed with caution.

[Edited on 13/5/14 by owelly]

The plasson fitting seals using an o.ring inside the fitting,
all the plastic screw on bits do is hold the pipe in the fitting
so the water pressure cannot force it out again, they only need to
be hand tight. Leaks are usually due to damaged o.ring, damaged
pipe or the pipe not pushed far enough into the fitting.

no ptfe needed but use a pipe support liner for mdpe pipe just to make sure

Noooooo

It will leak if you do

Have now engaged brain and realised it's not the thread that seals but the pipe.

quote:

---

Originally posted by owelly
These fitting don't like to seal on pipe that is scratched so just check the ends of the plaggy pipe.

---

This blooming pipe is still leaking. Its only a weep but not what I want!

I've stripped it apart, checked the o-ring and sanded the pipe so its smooth all around. Tried not to sand too much as I don't want to cause leaks that way!

The insert is in place.

was wondering if you can solvent weld this stuff? Could I glue a collar around the pipe to attach another 'clean' piece of pipe, to it?

Would the next size up from 32mm (40mm?) Work for this purpose?

Thanks!
James

Hi James,

You can't solvent weld MDPE pipe. Electrofusion welding would sort your problem, but you'd have to hire a welding kit and buy a new stopcock.
As has been said above, these fittings seal on the outside of the pipe so need unscratched pipe. I can't think of any fittings which seal on the inside of the pipe at 32mm, bigger stuff would be no issue.

Scratched pipe is the number one cause of customer complaints I get (I work as QA tech support for one of Plasson's competitors)

Shame you're miles from Doncaster, we have an electrofusion machine here.....

Not much help I'm afraid

Thanks for the speedy reply Marcus.

Hmmm. OK, well at least I'm not the only one!

Would I get a better seal with a different manufacturer? Or A brass straight joiner or brass stop cock?
Have seen 'push-lock' straight joiners on a video, are they any better?

Spent 2 weeks on this now. Rather beginning to question my DIY skills and whether I should be continuing with this project!

James

[Edited on 25/5/14 by James]

Don't panic James, it's an easy mistake to make. I always tape up the end 6 inches before pulling it through, to protect it.

You might be able to use a soft plumbing sealant to smooth any scratches. I don't think ptfe would work with a pushfit, though it would definitely work with a compression fitting.

My plumber friend wasn't keen on a plastic stop cock anyway saying it would get brittle and fail. Should I try a 32mm brass compression stop cock instead?

If I'd thought I would have protected the pipe more- assuming this is the problem.

I'm willing to sand it more but I cant see any more scratches so concerned I'll oval the pipe and it'll still leak!

using ptfe will not cause ANY isses at all

but... you would be better looking into why its weeping to start with?
if there is nothing amiss then just use some ptfe to help seal the threads

Putting ptfe on the threads will not make any difference to the leak, this type of fitting does not use the threads to seal against leaks.

If you can't get it to seal I think you'll need to cut the pipe back to where it's undamaged and extend with a good length using a straight coupling.

Use this on the scratched pipe and extend with a short fresh piece to put your stoptap on if you have room. May be cheaper if you look around

http://www.stc-plumbing.com/magento/index.php/mains-water-gas/polyethylene-blue-coils/conex-compression-fittings/32mm-fittings/conex-32mm-s301-pxp-str aight-coupler.html


Link doesnt work but in the mains water/ gas section conex do a 32mm brass coupler

[Edited on 25/5/14 by adam1985]

[Edited on 25/5/14 by adam1985]