Compression nuts and nylon olives are a very common connection type you will come across in plumbing installations. We use them for basin breech assemblies and in many of our exposed tapware & shower sets.

The following process applies to 1/2" and 3/4" nut & olive connections that we supply (and are best practice).

First put the compression nut onto the tube.

The nylon olive is then put onto the tube after it.

The tube is then inserted all the way into the receiving socket. Make sure it has bottomed out and cannot go further.

The nut comes down onto the thread and is firstly done up by hand and then tightened up firmly with a spanner.

If you are doing this with an exposed U breech tap or a riser tube on a shower set, the process is the same.

In our experience, compression nut & nylon olive connections are very reliable and only fail with the following two scenarios.

Both are caused by installation error.

1) The olive was installed without being fully on the tube.
This can occur by:

Having the nylon olive partially hanging over the end of the tube that it is meant to be compressing onto to when inserting into the receiving socket.

Taking a shortcut and having the nylon olive and nut already on the thread and inserting the tube through it. This risks the tube not going all of the way through the olive.

What are the signs of this?

The join will leak.

The join will not hold firm.

The nylon will be damaged / deformed and will likely not be able to be reused.
If you need to purchase replacements, the 3/4" nylon olive is listed here: PA8034.

2) The tube and nylon are seated correctly but the compression nut is not done up tightly with a spanner.

Hand tight or just a small nip of the spanner is not acceptable for a compression join. It must be firmly done up with a spanner.

What are the signs of this?

The join will not hold firm.

The join may have a small leak.

However on the plus side the nylon should not be damaged in this scenario and can be used to fix the join correctly.

Some other points:

Compression nuts do not need thread tape or thread sealant.

A compression nut & olive join that has been properly seated and tightened will not pull apart unless excessively ridiculous force is applied.

If the tube has been dropped, deformed or crushed where the internal of the nylon olive needs to engage then it will not seal.

Please note that an installer's failure to install a compression nut & nylon olive connection correctly is not a manufacturing fault and is not a valid reason for making a manufacturer warranty claim.