Can you use brass compression joints directly onto plastic pipe?

[Seb101]

I've been mulling over how I'm going to fit a brass diverter valve into an existing plastic pipe run to a concealed shower head without having to squeeze dozens of pipe accessories into the wall cavity. Reading around online I discovered it seems to be common/accepted practice to compression fit directly onto plastic pipe if it has a reinforcing insert.

What's the opinion here?

 

[fezster]

Yes, I have a brass compression elbow on 22mm polypipe which has been fine for ~5 years. I too read around on this at the time and the consensus seemed to be that this is absolutely fine (some saying they preferred it to the pushfit connectors). You must ensure you use the appropriate insert though.

 

[John D v2.0]

You should use a copper olive and the plain insert.

I prefer to connect to a short length of copper and then on to speed fit by a straight connector

 

[Seb101]

You should use a copper olive and the plain insert.

By 'plain insert' do you mean one without a rubber o-ring on the exterior?

 

[fezster]

You should use a copper olive and the plain insert.

Yes - copper olive is mandatory! Should have said that.

Recently had a problem with an imperial pipe onto a poly plumb tee. It had been weeping for many years. Most likely an incorrect O ring was used on this particular fitting, as one side was fine. Anyway, it was replaced with a brass compression fitting with an imperial olive for the imperial pipe, and a normal olive for the poly pipe.

 

[Seb101]

By 'plain insert' do you mean one without a rubber o-ring on the exterior?

I.e. this:

not this:

 

[John D v2.0]

Yes that picture

I.e. this:

not this:

correct