Compression Joints - how tight and which type of olive?

[Blitherer]

I am never sure how tight to make these joints - I have read hand tight plus a quarter turn, but this never seems tight enough - do I just keep tightening until the dripping stops?

It seems to be worse with cheap connectors. E.g. I have a washing machine tee from toolstation (15mm x 15mm x 3/4") which seems to need a lot of tightening. This particular connector does not even have a flat area on the body of the connector for a wrench, so is very hard to tighten.

Might it be an idea to replace the olives? These connectors seem to have copper olives - are brass ones better? Should I use PTFE tape over or under the olive?

TIA for your help
M.

 

[Burnerman]

I use copper olives where I can - especially if its awkward to get to the joint for final tightening - otherwise brass ones are fine.
How much to tighten is really a matter of practice - you dont want to overtighten the joint or you'll distort it - and brass olives need more tightening force than copper ones.
Use a sealant over the olive if its a used fitting, and a wrap with PTFE (again over the olive, and not on the threads of the coupling) for the belt and braces approach.
John

 

[JohnD]

I put PTFE tape over the olive. Since I started doing that my joints have been sound and leak-free. I can't recommend it too highly. You need to trial-assemble the joint first so the olive is held in the right position, or it may move. No need for jointing compound.

I am not a pro, just a numbskull DIYer

 

[Nige F]

I put PTFE tape over the olive. no need for jointing compound.

I am not a pro, just a numbskull DIYer

I`ll agree with that

 

[gasbanni]

Always use copper olives,throw brass ones away alway use jet blue.
Just a firm nip up no need to swing on it.
Overtightening is as bad as not tightening up.

Olive should be compressed on the pipe but the pipe should not be deformed.
Practice makes perfect.

 

[Whitespirit66]

PTFE on olive = DIYer

Smear of jointing compound (Boss White) on olive = Pro

 

[JohnD]

I already said

I am not a pro

and this is DIYnot

I find it works better than compounds, even 1960's ones like Boss White.

 

[Whitespirit66]

Been around since the 60s?

Like Jagger and Daltrey, quality lasts!

 

[htgeng]

PTFE on olive = DIYer

Theres only one thing worse than seeing PTFE on an olive, thats PTFE sticking out of the threads of a compression coupler. I think in any professional plumbers opinion that is a hanging offence and is an easy identifer of cowboy/bodgit/diy plumbing in the rest of the house.

How many other pros on here would agree with that?

 

[Alz0r]

PTFE on olive = DIYer

Theres only one thing worse than seeing PTFE on an olive, thats PTFE sticking out of the threads of a compression coupler. I think in any professional plumbers opinion that is a hanging offence and is an easy identifer of cowboy/bodgit/diy plumbing in the rest of the house.

How many other pros on here would agree with that?

I've seen PTFE on the threads of an isovalve going up to a RAD in a Plumber's Merchant!!!

Surely that would create a blackhole into which the whole world would collapse?

 

[JohnD]

...PTFE on an olive...

yes, and there's only one thing in its favour.

It works

 

[Axel]

The main reason it is important to do a compression joint nice and tight is not to stop it dripping, but most importantly to make sure that the olive has sufficiently dug into the pipe to prevent the risk of the fitting catastrophically blowing off the pipe under pressure. Using PTFE is inadvisable as it means the olive may create a succesful water seal before it is tight enough on the pipe to make a secure connection.

LSX is the modern pipe sealant, although Boss White is better in some ways as you don't need to clean it off if you need to open the joint.

 

[Whitespirit66]

...PTFE on an olive...

yes, and there's only one thing in its favour.

It works

Piping the gas to a boiler in Speedfit pipe and fittings will work.

Just because a bodge works, doesn't make it right!

 

[gasbanni]

PTFE on olive = DIYer

Smear of jointing compound (Boss White) on olive = Pro

Boss white pro
Jet Blue real pro

 

[Whitespirit66]