Jointing Compound On 15mm Plastic To Brass Compression Fitting?

[EViS]

I'm a fan of jet lube (or the much hated - boss green) on all copper pipe to brass compression fittings. However, should jointing compound be used around a copper olive on plastic (i.e. speedfit) to brass compression fittings (e.g. plastic running into concealed shower valves, wall elbows, etc)?

I've always applied a smidgen, but do wonder whether the compound could react with the the plastic? Or whether it's doing more bad than good?

 

[ShaunCorbs]

No leave dry

 

[Sharp Point]

Do you mean an olive and brass nut on a 1/2” plastic shower inlet?

If so, I use I few wraps of ptfe over the olive.

 

[Jim Goodenough]

No leave dry

If so, I use I few wraps of ptfe over the olive.

Go with dry if you get a weep, use PTFE or Loctite 55.

 

[king of pipes]

Hep silicone spray to help insert push fit fittings , as above a few wraps of ptfe on the olive when used on plastic if needed no paste on plastic definitely not . Cheers kop

 

[Scott_D]

I can never remember if it should be a brass or copper olive onto plastic

 

[ShaunCorbs]

I can never remember if it should be a brass or copper olive onto plastic

Copper

 

[EViS]

Thanks chaps. What's your reasoning for not using any form of jointing compound on plastic? Does it degrade the plastic?

 

[king of pipes]

It is not needed and should you be unlucky enough to have a failure the manufacturer will have a reason for not admitting liability as the fittings have not been installed as their instructions. Cheers kop

 

[rpm]

Go with dry if you get a weep, use PTFE or Loctite 55.

Loctite 55 on an olive, are you for real?

 

[jacob BRISTOL heating]

hi Evis,
Compression joints are designed to be used without any sealant

 

[EViS]

hi Evis,
Compression joints are designed to be used without any sealant

This is true. But the reality isn't always up to the design . But I guess we can debate this subject all day. I was more interested in for those of us who use a compound on copper, whether it should also be used on plastic .

 

[king of pipes]

Copper yes plastic no .