Weeping compression Joint

24 Oct 2006
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United Kingdom
About 6 weeks ago I had to replace an old compression joint on my hot water pipe (from a combi boiler), the pipe one side is 3/4 in and 22mm the other, managed using a 3/4 olive on a standard 22mm compression fitting to join them and appeared to be sealed, did use some ls-x jointing sealant as well as found it difficult to get a good conenction on the 3/4 in side. However 6 weeks later has started to weep from the 3/4 side. Should I just tighten the nut onto the compression joint a bit, to see if this will solve the problem, or do I hve to go back to square one and fit a new olive etc. Loathe to do anything that will make it worse. Pipework is in an awkward position hidden in a cavity. Your expert comments would be appreciated. have normally found that once joint is sealed it stays sealed so not sure why it has started to weep after this time
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Back the nut off and put a few wraps of PTFE round the olive then tighten back up, sorts 99% of leaking compression joints.
was the olive a 22mm or a 3/4" size? (they are not quite the same).

If you made it using LSX you will have to clean it all out of the joint, as it will have set hard now.
thanks for the advice, i have used a 3/4 in olive on the 3/4 pipe side and a 22mm one on that pipe. Still unclear why after 6 weeks it has started to weep, Can anyone shed any light, especially as the lsx sealant should have sealed everything inside the fitting
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one answer, because leak sealer compound on compression fittings is crap.........infact its crap full stop! PTFE all way, not only it it less messy but it gives you a better joint and does not set and go hard meaning if the joint has to come apart again (like in your case) it is easier to undo the fitting .
HarrogateGas said:
one answer, because leak sealer compound on compression fittings is rubbish.........infact its rubbish full stop!
I also like PTFE tape, Hg, but I don't share your opinion of LSX. Used judiciously it's a godsend; for example, on parallel BSP threaded male/female joints.

Paste, on the other hand, has no redeeming features.
I obviously have opened a can of worms amongst u professionals about different sealants etc. In using ptfe tape should i pull the pipe from the fitting and wrap it around the piece of piping between the end and the olive, or can i just wrap it around the olive when the pipe is still pushed in... if that makes sense???
Leave it in if its easier, wrap olive and over thread slightly in other words mummyfy it .
Wouldn't agree with that. You don't want water getting out from the fitting body, so the important seal is between the end of the male threaded part and the olive.
The seal between the olive and the pipe isn't usually any problem.

Have also had joints leak, and still leak when done up a bit more, but stop leaking when some paste is appllied. It doesn't harden much. (I use one of the ones with a brush in the lid like Virgin White). I used to be in the No Sealant Should Ever Be Used camp, but I've changed my mind. It depends.

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