Why do my compression joints keep leaking?!

[DLaing]

I've cut the pipes square, cleaned them with wire wool, applied silicone jointing compound under over and around the olive. The I've hand tightened and finally finished off with a spanner.

Despite all of this, they still have very tiny leaks - so small that you just get the occasional dab on a tissue. The problem is the joint is on the pipe work to a radiator on a pressurised system that I'm going to bury under a ceramic floor. I would ignore it but it'll always be there in the back of my mind!!

So what's the solution? Do copper olives help? Will dismantling and applying some PTFE tape around the joint make it water tight?

HELP!

By the way, are Cuprofit pushfit copper fittings any good? I'm tempted to use one of those instead?

 

[Bahco]

Are you pushing both pipes all the way home in the fitting and are they staying put when you tighten.
You could try wrapping ptfe tape around the olive (approx 3-4 turns) will do)
Overtightening or under tightening will also cause leaks. If you haven't got the knack I would consider hep 2 o.
Good luck

 

[sasolshares]

As bahco says, a bit of ptfe tape around the olive works well. Copper olives often more reliable as softer than brass, so compresses better with less tightening force.

 

[TexMex]

applied silicone jointing compound under over and around the olive

Is this a new product? I've never used silicone on compression joints.

 

[DLaing]

It's called Dow Corning Plumba Joint. Is this a good idea on a compression joint? If not, what do you suggest?

 

[TexMex]

I must confess, I'm a bit of an old fasioned type, hence the ignorance concerning silicone jointing compound. Having looked over the data sheet, however, I note that it specifies "For jointing threaded fittings and for sealing leaks." No mention of compression fittings. I also notice that it is "tack free in 2 hours"

The seal around an olive in a compression joint is, a somewhat different animal, to a plain threaded joint. Since compression joints are so abundant in plubing circles, if this product was suitable for them, I'd expect Dow Corning to specificly mention them in the data sheet.

Add to this the evidence of your own experience, I would strongly suspect this product in this application. Have another go with something like Boss White. It's been tried and tested, successfully by millions!

 

[DLaing]

It's called Dow Corning Plumba Joint. Is this a good idea on a compression joint? If not, what do you suggest?

 

[DLaing]

It's called Dow Corning Plumba Joint. Is this a good idea on a compression joint? If not, what do you suggest?

 

[sasolshares]

I know someone who puts a ring of hemp on the joint side of the olive when all else fails, always works.

 

[mave]

FWIW: You shouldn't be using compression joints if you're going to bury them. Better to solder and wrap in denzo tape.

 

[kevplumb]

or use plastic and make the joints where you can get to them