Weeping compression fitting

[markwm]

I re-plumbed our radiators today. I used some new copper pipe on some and re-did the compression fittings with new olives etc.

I thought I did them perfect, plenty of PTFE tape, but when I refilled the system I found two leaks, both in the same spot on different radiators.

They were weeping ever so slightly from the bottom of compression nut that compresses the olive. So drips would runs down the pipe.

I redid the fittings 3 times, tried a different nut but one still leaks slightly. I really don't know what I did wrong.

Should I be using some sealer around the compression olive? It doesn't make sense to me that the ptfe tap is faulty as surely it would be leaking from the top of the nut, not the bottom.

 

[Gasguru]

Use a jointing compound such as Hawk White. A smear around the olive and a little on the threads will reduce the friction and gaurantee a leak free fitting.

 

[bengasman]

Teflon tape is for tapered fittings as they seal on the thread, no need for it on olives.
I always clean the pipe with steelwool, little burrs can make an olive leak.
If you want to be perfect, you can put a little gassealant on the pipe before you slip the olive on, though in theory it should not be necessary.