Olive does not hold plastic pipe

[frediaz]

I bought some radiator valves which I connected to 15mm plastic pipes. The valves have olives with a semi-circular profile. When I did a pressure test, the valves got ejected from the pipes and flooded the area. Elsewhere, the connections have olives with a facetted profile and there were no leaks.

I have noticed that the facetted profile olive has a sharp edge that slightly bites into the plastic pipe, whereas the semi-circular olive does not. Is this the reason? If so, are they interchangeable and can I just replace the semi-circular olives with the facetted ones? Or any other suggestions?

I am always afraid to over-tighten the connections for fear of damaging them, as I have done a number of times.

 

[gremlin16]

Have you fitted the inserts inside the plastic pipe.

 

[Razor900]

Make sure you are using the correct inserts for the plastic and you should only use copper olives with plastic not brass ones. The shape doesn't matter as much.

 

[Agile]

Some of the copper olives have an asmetrical profile which is probably slightly better with plastic.

If you have those then I would used then with the nut against the steep angle.

Tony

 

[frediaz]

Have you fitted the inserts inside the plastic pipe.

Yes, inserts from the same manufacturer as the pipe

 

[frediaz]

Make sure you are using the correct inserts for the plastic and you should only use copper olives with plastic not brass ones. The shape doesn't matter as much.

As a matter of interest, why is this?

 

[Razor900]

The brass olives are much harder and can cut into the pipes, most manufacturers instructions for plastic tell you not to ose them.

 

[blondini]

Have you fitted the inserts inside the plastic pipe.

Yes, inserts from the same manufacturer as the pipe

They could still be the wrong ones. e.g. Speedfit superseal inserts shouldn't be used with compression fittings, their plain inserts should be used instead.