I have recently extended some pipework using compression fittings. It had been suggested to me that I should not over tighten the fitting as the olive could cut into the pipe. Now I have notice on a couple of the fittings that whilst they appear water tight there seems to be a powery deposit forming round where the pipe goes into the fitting. It suggests to me that I have not tightened them correctly but would appreciate any feedback.
Thanks
David - Milton Keynes
If they are watertight then leave well alone!
Water *has* been leaking very slowly - and had probably immediately evaporated, so you won't have seen any liquid - but it has left this deposit. The original leak may well have silted up and cured itself. Try cleaning the fittings with wire wool, and see whether the deposit re-appears.
The olive has to cut into the pipe -- that's part of the water tight seal. You can overdo tightening though and deform the pipe or olives to the point where they can seal anymore.
Yes (or overtightened). Really you should undo the joint to clean out the crud rather than risking tightening crud into the water sealing surfaces.
The powdery deposit will be limescale from a slight leak which is evaporating. Better to cure it.
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A correctly tightened compression fitting should have the ring compressed so that it can't be removed from the pipe easily. And you'd have to use a deal of force to overtighten one. So not easily done with the correct spanners. You'd have to be using extra long types.
IMHO most give problems because of damage to the pipe in some way - linear scratches being a favourite cause by the pipe being pushed through some small hole etc. That's the beauty of a soldered joint - if the pipe and fitting are cleaned properly solder will fill any such small irregularities.
On Sun, 13 Jan 2008 09:53:13 +0000 (GMT) someone who may be "Dave Plowman (News)" wrote this:-
Indeed. So far I have yet to over-tighten one, though no doubt that day will come. I don't hold the end of spanners and then swing on them as some people do.
If the pipe and fitting have been cleaned properly (wire wool and a wipe, no scratches), a compression joint will be just as fine! You can get away without cleaning a soldered joint as well (with powerful flux), true, but they're the same if properly cleaned.
I once heard that plumbers "never fully tightened compresssion joints because, if there's a leak they still have something to tighten".
It is also true that , for a properly tightened compression joint (finger tight then 1/4-1/2 a turn), you won't get the olive off.
Don't forget to clean the olive as well as the pipe/fitting.
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