New v old 15mm olive; different external diameters

TheGreenFrog

I am about to reconnect a compression fitting.  I was intending to replace the olive but the old olive (which I have taken off) is more substantial than the replacement olive I have bought from Screwfix (17.8mm external diameter v 16.8mm for the new one, as measured with calipers) and I am wondering whether it is safer to reuse the old fitting with a bit of V2 Jetlube.  Is it normal for olives of a given internal diameter to have different external diameter measurements?

FreeBear

It is the internal diameter that is important with olives. The outer diameter doesn't matter as much as it is the tapered ends that make the seal.

Section62

TheGreenFrog said:

I am about to reconnect a compression fitting.  I was intending to replace the olive but the old olive (which I have taken off) is more substantial than the replacement olive I have bought from Screwfix (17.8mm external diameter v 16.8mm for the new one, as measured with calipers) and I am wondering whether it is safer to reuse the old fitting with a bit of V2 Jetlube.  Is it normal for olives of a given internal diameter to have different external diameter measurements?

As FreeBear says.

If you are reusing the fitting then make sure the threads are fully clean - the effect of a slightly reduced external diameter olive (if anything) would be the nut needing to go on a little further than for a larger diameter olive.

You can check the olive by test assembling the connection (without the pipe) and make sure you can hand-tighten the nut onto the new olive with a few clear threads to spare.