Using existing olive on pipe

[diyjunky]

Removing an olive from some 15mm pipe will be very difficult. We are aware of the options such as olive puller, sawing off etc but we want to try and use a new isolator valve with the old olive in place as a first attempt. My friend who has done this before has used LS-X (probably because this is what is in his tool box) to help the olive re-seal.
If I was going to doing it, I would go for PTFE tape as it has a thicker physical presence and is squashable but I have read that PTFE isn't the optimal solution to this.
Should we use LS-X, PTFE tape or some other compound for the compression joint in this unavoidable scenario ?

Thank you.

 

[oldbuffer]

1. With the old isolator off, make sure the new one will fit the old compression nut. It almost certainly will, but worth checking.
2. When re-using an old olive, it is worth using some additional form of sealant, as the olive will have been squeezed by the compression nut and old fitting and may no longer be truly round.
3. You could use:
3.1 A sealant like LS-X, which sets rather like silicone sealant.
3.2 One like JetLube V2, which doesn't set.
3.3 A "solid" sealant like PTFE tape.
4. The sealant needs to be applied around the old olive, not always easy in restricted space. There is no point in applying it to the threads.
5. Applying PTFE tape in a restricted space can be eased by wrapping a length of PTFE around a pencil, cutting it from the reel, then applying it from the pencil by rolling round the olive. Apply it in a direction such that screwing the compression nut on won't unravel it.
6. My own preferences (in order) are:
6.1 JetLube, because I've never had a leak using it.
6.2 PTFE tape, because its cheap. I use 5 or 6 wraps of ordinary PTFE tape. You can use gas PTFE but need less because its thicker. However, I find this make it harder to apply with restricted access.
6.3 LS-X, but every time I come to use it (infrequently) its dried up and I have to get some more.

 

[diyjunky]

Point 1. concerns me slightly because we are actually going to be removing a compression fitted magnetic scale inhibitor. I just assumed that the nut /olive combination would be standard. Another thing to worry about.
Using the pencil sounds like a smart idea to apply the PTFE. Thanks for that.

Edit: does LS-X need to set in the compression joint before re-applying mains water pressure ?

 

[Madrab]

but I have read that PTFE isn't the optimal solution to this.

Yes it is, fire a few wraps on if the olive is in good condition. If the olive is squashed or mis-shaped due to overtightening then a new olive and possibly a piece of pipe would be recommended.

 

[diyjunky]

So PTFE is preferable to LS-X / compound in this specific example ?

 

[oldbuffer]

1. It might help if you could provide a photograph showing what you are trying to disconnect / replace.
2. Post #2 refers to my preferences. It doesn't matter too much what you use. An advantage of PTFE or JetLube is that they are non-setting, which makes it a bit easier next time you have to replace.
3. If the difficulty is because the compression nut is within a narrow necked cavity, tools like a crows foot (e.g. Shetack) spanner or the Armeg tap spanners can help. The latter aren't cheap.

 

[Madrab]

So PTFE is preferable to LS-X / compound in this specific example ?

I wouldn't say it's preferable, pro's tend to use what they have or what works. I always carry gas PTFE so any time I re-use a nut and olive then the olive gets a wrap of tape and job's a guddun

 

[diyjunky]

Want to remove the useless scale reducer and put in an isolator, none return valve and mini expansion vessel.
The only room we have is the space to right of the pipes. We need to use a full flow 22mm none return valve so as to not reduce flow to the combi too much. The cold water pipe leaving the scale reducer is not accessible as it disappears behind a tiled box section before entering the boiler. The boiler installation is neat (in kitchen) but all very tight.
Plan is the put a couple of 15mm compression couplers where the scale reducer is and put the new pipe work in the space on the right using large radius pipe bends to keep a good flow rate. We might not be able to remove the olives and I am very cautious of damaging the small amount of copper coming of the bottom tee joint.

 

[Madrab]

As long as they haven't been overtightened then it shouldn't be an issue to re-use them. .

 

[diyjunky]

Is PTFE and LS-X viable .... or something that's just not done ?

 

[Madrab]

Is PTFE and LS-X viable .... or something that's just not done ?

Nah, bit like a double entendre, kinda doing the same thing with 2 different mediums. No real benefit TBH.

 

[johnny2007]

Just tighten it up as you would normally do.
Then if it leaks use other methods.
If it's not been deformed by overtightening it will be fine without anything else.

 

[Madrab]

If it's not been deformed by overtightening it will be fine without anything else

Have to disagree - if a new fitting is used on an old olive, experience has shown that the end that doesn't twist and re-shape the olive surface, i.e the new fitting's fluted end sometime doesn't sit on olive the same way as the last fitting did and it can weep. For all it takes to put a wrap or 2 of tape to remove that risk and a bit of grief.

 

[johnny2007]

Have to disagree - if a new fitting is used on an old olive, experience has shown that the end that doesn't twist and re-shape the olive surface, i.e the new fitting's fluted end sometime doesn't sit on olive the same way as the last fitting did and it can weep. For all it takes to put a wrap or 2 of tape to remove that risk and a bit of grief.

That's why I said to try it first and check if it weeps.
2 minutes job possibly avoiding the mess of paste or ptfe tape.

 

[Madrab]

That's why I said to try it first and check if it weeps.
2 minutes job possibly avoiding the mess of paste or ptfe tape.

Nah, why bother, there's no mess sticking on a wrap or 2 of tape around the olive and it avoids the extra minutes of isolating and draining down again, especially for a DIY'er, who then may worry about a fitting that's leaked as to whether it will do it again.