MDPE adapter joint weeping problem

[Ed21]

Hi All, lI'm using an adapter to join blue MDPE with the older black Alkathene? pipe.

Blue no problem and tight, but the black joint is weeping a bit.
This will be burried so although it's not leaking much, not exactly happy with it like that.

I'm resigned to having to take apart again, but with the exception of a squirt of silicone spray
any ideas as to how to ensure the joint is tight? 

Thanks - Ed 

[nod]

Rap some PTFE tape around it and bury it 

[stu w]

It should not  leak so a few reasons why it could be . The incorrect  fitting possibly  the old stuff is usually 19/20mm depending on what has been used, make sure you have the correct plimac/ plasson adaptor.

The pipe has a mark/indentation where the fitting is .

The o ring has been kinked when putting it together? 

Incorrect insert ? 

Transition couplings should be 100% leak of the correct type and installed correctly 

 

Edited April 18 by stu w

[Ed21]

Yes I've done all the usual  

It's Blue 32mm standard > going to a 25mm-33mm Universal adapater > Black Imperial 

It's got a cone star shaped hard rubber seal that looks to reduce when screwed up. 
By the looks of it the smaller diameters will push in a lot further, so gain more grip. 

Next size up was 35mm + so was too big. 

Will be doing it again, but was thinking that maybe using some silicone grease (suitable for drinking water) 
in the cone might be enough to get it in a bit further and aid the seal . Pipes wioll be flused after - any reason why not? 

[Ed21]

Here you go 
 

[Alan Ambrose]

Couple more possibilities - pipe wasn't deburred and/or o-ring is torn (look closely). Star washer thing is a bit snagged or on at an angle.

 

Took me a while to figure out that the seal on these is only the o-ring. Any tape / gunge is just covering up a bodge and there'll be an underlying reason to look for.

[Ed21]

Yes I deburred it, but will be dilligent when I do it again.
Was a new fitting and seals all good.
Blue was a pain, usual rolled up transport storage curve, but black was straught as coiuld be. 

Just  going to do it again and check every stage. 

[Conor]

I've used the same fitting on an old lead pipe. They shouldn't leak at all. Is everything straight? How did you tighten it? I find hand tight often isn't enough for those (years of experience installing meter boxes.)

[Ed21]

Yeah black was straight, but the blue had a curve although this bit didn't leak. 
Used 450mm adjustable monkey wrench for the collar and same sized stilsons for the body. 

Tigtened up as far as I dare whiile watching the thead. It's tight. 

 

[saveasteading]

I'm a recent convert to this stuff.

I've recently done a couple of pipe repairs with it, including exactly your issue.

 

 

Fernox LS-X Leak Sealer 50ml (23614)

 

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[Ed21]

First read that and thought no, then thought why not?
Fitting will have to come apart anyway, so will get a tube and see

[Alan Ambrose]

I might get a new fitting, preferably Plasson,and try again. Btw there’s some special plastic spanners that work well on those fittings. I don’t think the tightening torque makes a difference though, it’s the o-ring that counts.

[saveasteading]

5 hours ago, Ed21 said:

so will get a tube and see

It was one of the champions on BH who I saw recommended it instead of ptfe tape. , hence I tried it 

My surprise recent success was with a biggish (40mm?) pipe on a pumped circuit. I was close to accepting that I must cut the pipes and start again, but it worked with fernox.

The other advantage is that it can be spread round the back and all round even when space is tight. Plus it replaces the need for the recommended 25 turns of ptfe on plumbing in other countries where the tolerances are different.

[Ed21]

On 19/04/2024 at 23:27, saveasteading said:

It was one of the champions on BH who I saw recommended it instead of ptfe tape. , hence I tried it 

My surprise recent success was with a biggish (40mm?) pipe on a pumped circuit. I was close to accepting that I must cut the pipes and start again, but it worked with fernox.

The other advantage is that it can be spread round the back and all round even when space is tight. Plus it replaces the need for the recommended 25 turns of ptfe on plumbing in other countries where the tolerances are different.

Bought a tube, but used a smear of drinking water rated silicone grease on the seals and it worked !!!!
Still a good shout though, will add to the backups.