How many turns when fitting compression isolation valve?

[OxfordJules]

I've never done one before and, as usual, Google is offering conflicting advice. I'm fitting one of these (from Screwfix, 15mm). I've read that ...

• Over tightening is the commonest cause of leaks.
• Once you've got it finger tight, you need to tighten a further half turn / full turn / one and a half turns / quarter turn / until it feels "right".
• Don't forget that over tightening is the commonest cause of leaks!

Obviously, it depends on the size and type of fitting so I was wondering if anybody had any experience of these specific fittings. I'm thinking they must be very commonly used - there are certainly plenty of existing ones around my house.

If you had, my question is ... once finger tight, how much more tightening is needed? i.e. quarter turn, half turn, full turn, etc. I don't want to do it because, as we all know ... over tightening is the commonest cause of leaks!

Thanks everybody and have a great weekend!

 

[Roy_66]

Well I've just done some recently as an amateur to fix my kitchen tap. . .

First I take it you are doing water not gas (gas requires special qualifications and rules different)

My take: Use copper olives and a dab of sealer. I'm behind the times and my choice of Fernox LSX is a bit odd perhaps these days.

The tightening depends a bit on the fitting and the pipe, but mine go about 1/4 to 1/2. I always stop tightening if the fitting creaks/groans as I guess that is the olive compressing and the fitting juddering along the olive to take up the slack. So stop at that point because you have some compression. If in doubt stop.

Think there is some confusion over manufacturer 1.25 turns cos that relates to range of pipe sizes not just 15mm, and required fraction of turns depends on pipe size. The manufacturer may also be using different pipe. I'd take their spec as an upper limit that may be wrong for your (and mine) pipe.

For good understanding have look at Allen Hart's video on "How Compression Fittings Work":



One other amateur tip - the iso valve you show will need a good pair of grips to hold it. If you buy the Pegler version from Screwfix which is a bit longer, that has a nice hexagon in the middle so you can get on a nice big adjustable and don't need so good hand strength:

https://www.NoLinkingToThis/p/pegle...UkW93p6GXNaU65FcLyRoCgfkQAvD_BwE&gclsrc=aw.ds

One other little trick I do is a few bits of vaseline on the nut threads to make the tightening smoother and easier (and the undo one day).

Lastly if reusing an old olive i.e. leaving it on the pipe, then only need about 1/4 turn as it's ready crushed. Just clean it up well first and a dab of your chosen sealer.

And always remember if it's not fun to use a professional. They have tricks like cutting off old olives and fitting new ones if it goes wrong.

You could have a practice in the garden if not confident. A 3/4 inch (that's pipe inside dia) male BSP fitting will connect to a hose lock tap adapter. The pro's all went through a learning process so treat yourself.

Compression is a good choice for an amateur.

Please post another question if you have more e.g. think about rotation of the pipe for about the last 30deg of turn (it tends to turn with the nut)

P.S. Don't forget pipe support - make sure finished work cannot flap about. That will help keep fittings together, especially any push fit if you ever do those one day.

Best of luck,

Roy (Amateur - sorry for ramble - laid up getting over reaction from 4th COVID jab. . .)

 

[OxfordJules]

Thanks very much Roy - tremendously helpful answer and I'm sorry to hear you're laid up. I didn't know we were on four jabs already - I'm still on my third.

Yes, it's water (I should have mentioned) and I did try outside with a garden hose but I couldn't get a good seal between the hose and the pipe - I didn't have the fitting you mentioned, just a jubilee clip. And I have been using a thin smear of sealer - I think I'm just finding it difficult to find the Goldilocks zone between not tight enough and too tight, so I'm taking the approach of under tightening (I think!) and then tightening a bit more, in steps, until the occasional drop goes away. But that makes me feel like a rank amateur, which I am of course!

 

[Roy_66]

Thanks very much Roy - tremendously helpful answer and I'm sorry to hear you're laid up. I didn't know we were on four jabs already - I'm still on my third.

Yes, it's water (I should have mentioned) and I did try outside with a garden hose but I couldn't get a good seal between the hose and the pipe - I didn't have the fitting you mentioned, just a jubilee clip. And I have been using a thin smear of sealer - I think I'm just finding it difficult to find the Goldilocks zone between not tight enough and too tight, so I'm taking the approach of under tightening (I think!) and then tightening a bit more, in steps, until the occasional drop goes away. But that makes me feel like a rank amateur, which I am of course!

The sealer should be belt and braces, but let it dry a bit (if it's a setting type) before turning the water on. Intrigued how many turns you apply and get a leaking fitting.

One silly point - put a mark on the pipe with felt tip to make sure the pipe isn't being pulled out the fitting on tightening.

Assume you are buffing the pipe up after cutting to length and deburr. Examine it for faults also the bevel sealing face on the fitting.

Don't give up. Something simple wrong.

Your method is the professional one i.e. don't overtighten as first step. If you are dry now then sorted.

Cheers,

Roy

 

[Roy_66]

Thanks very much Roy - tremendously helpful answer and I'm sorry to hear you're laid up. I didn't know we were on four jabs already - I'm still on my third.

Yes, it's water (I should have mentioned) and I did try outside with a garden hose but I couldn't get a good seal between the hose and the pipe - I didn't have the fitting you mentioned, just a jubilee clip. And I have been using a thin smear of sealer - I think I'm just finding it difficult to find the Goldilocks zone between not tight enough and too tight, so I'm taking the approach of under tightening (I think!) and then tightening a bit more, in steps, until the occasional drop goes away. But that makes me feel like a rank amateur, which I am of course!

P.S. . . . sorry forgot to say the 4th jab is just for immune compromised / vulnerable. I'm at the very good end of that scale though.

 

[OxfordJules]

Roy, I've given the leaking joints a bit of a tighten and I'm relieved to say they're now all looking good, and not a whiff of PTFE tape anywhere! I think I might just have been unlucky with my very first one; I gave that an extra nip and it started leaking more, so I didn't know what was going on.

Take care. Julian.

 

[Roy_66]

Roy, I've given the leaking joints a bit of a tighten and I'm relieved to say they're now all looking good, and not a whiff of PTFE tape anywhere! I think I might just have been unlucky with my very first one; I gave that an extra nip and it started leaking more, so I didn't know what was going on.

Take care. Julian.

Glad you are sorted. Assume you threw that first one away.

Think I'd try some sort of sealer in future. I can't remember one I've had leak (guess about x50 in my amateur plumb lifetime).

Perhaps write a new post and ask what people's favourite sealer is? (or none) and do they bother changing from brass to copper olives.

Enjoy the weekend.

Roy

 

[ShaunCorbs]

When the nut is hand tight around 3/4 of a turn

Jet blue v2
And either it’s easy to compress copper olives so you have to be careful but brass requires a tad more force