Leaky compression joints - which jointing compound?

[autolycusd]

I've just plumbed in a complete bathroom and extended the CH system upstairs. The CH i did using copper end feed joints and it went without a hitch. I've used a mixture of plastic and copper for the bathroom using standard compression fittings as i'm wary of using push-fit, especially as the floor will eventually be tiled.

I used no jointing compound on the plastic pipe, and many of the joints are weeping now i've connected up the mains. I believe all of the suspect joints are the plastic ones. (I used purimachos compound on the copper joints, tho' i now realise that it's not suitable for potable - my mistake!)

I was advised not to use compound by a plumber, who also said i should never use a linseed based one on plastic as it will degrade it. However, looking at the many types of compound available, none i have seen is recommended for copper pipework only.

So i intend to do all the joints again with compound and hope that cures the problem. The question is, what's the best one that is OK for copper and plastic and hot and cold potable water? Any constructive comments most welcome. Thanks.

 

[adlplumbing]

did you use inserts

 

[autolycusd]

did you use inserts

Hi - yes, i did.

 

[adlplumbing]

did you screw the end after pushing past the first stop

 

[autolycusd]

did you screw the end after pushing past the first stop

Do you mean did i push the pipe through the olive into the fitting as far as possible before tightening? If so, yes, i did.

 

[adlplumbing]

no i meant the push fit

 

[bathstyle]

He didn't use push fits, he used compressions.......

I'm not sure if there is a compound available for plastic, most people would use PTFE around the Olive but as it's a DIY site, best pop it round the thread as it looks nicer.

 

[adlplumbing]

sorry missed read it happens
yep use ptfe after the olive
and rember to use it so it self tightens

 

[seco services]

can't see how every joint is weeping unless you've overtightened them.

 

[autolycusd]

can't see how every joint is weeping unless you've overtightened them.

Well, not every one but a few. Maybe i have overtightened - what can i do about it? I have seen jet blue recommended as a compound for plastic, but i believe it's only suitable for cold water. There's also tru-blue, which i understand is ptfe-based. Might that be suitable? Or is ptfe tape around the olive and'or thread the only option?

 

[adlplumbing]

no ptfe aftyer the olive into fitting is best ad cheapest option
not on the olive and not on the thread

 

[Burnerman]

Just a few wee points:
Ensure your plastic pipe isn't scored after being pulled through cavities etc
Cut the ends with a proper pipe slice
Use the correct insert (stainless steel ones preferred)
Use copper olives if you can
Smear the olive with Jet Blue
Nip the fitting up smoothly in one go.
John

 

[autolycusd]

Thanks to all for the comments and suggestions. As a DIYer, compound appeals more to me than tape, but the jet blue appears only to be recommended for cold water. Not sure about tru-blu.

Also, IF i've overtightened (and from reading the forums it seems some think this can't be done!) can i recover simply by adding tape/compound? Or should i try to replace the olive - which i imagine is near on impossible?

 

[misterdubya]

The common problem with cc/ccc plumbers or DIY'ers is that they put compounds in the wrong place.

You must never smear it on the olive, you lightly smear it on the pipe ABOVE the olive.... ie where the pipe tightens to the fitting above the cone /olive.

adl has explained this already. Do that, and it won't leak.

Mr.W.

 

[Heat4input]

unlike te other replys,you should smear it on the pipe between the olive and the fitting,and on the olive if you like,sorted