The message from "." contains these words:
Well, I've never had a compression joint leak and those I've taken apart have all had the olive pressed into the tube slightly. If that isn't deformed I don't know what is. I'm using "deformed" in the sense of "taken beyond its elastic limit". You may be using some other meaning.
perhaps deformed was too strong a term for /compressed/ ? :)
I use it as well but only on old fittings or where there is a problem. I've NEVER ever had one leak or one come apart.
I saw Tommy Walsh using the same method recently ;-)
What I don't get is this recent puritanical aversion to PTFE tape in this NG. Has someone gone short on PTFE tape manufacturers' shares?
The message from "." contains these words:
No, compressed is something different. To my mind it implies the ability to spring back, which pipe won't do after an olive has been squashed on to it.
PTFE tape works best in a threaded coupling...as a thread filler, Its less effective in an olive because by and large, its not strong enough.
All olives MUST permanently deform the copper pipe enough to grip it reliably.
The problem is once you start, its easy to go too far and get to the limits of the thread to compress the olive. Such a joint has no more 'slack' left in it, and will be unreliable when re-used. Filling it up with PTFE tape MAY just bulk it out enough to be watertight..but I am dubious as to the longevity on high pressure systems.
Compressed is just the opposite of tensed...
c.f. compressive load and tensile load
Ben
My (lesser powered) shower pump can on occasion squeeze a trickle of water out of it's push fittings :-(
why call it a /compression/ joint then ? in your world it would be called a deformation joint which it isn't, it's a /compression/ joint. methinks you're splitting hairs, why is anyones guess but if the copper *tube* /deforms/ the joint is and will be defective.
On a 1/2" fitting it requires a brutal effort to tighten one to this extent. And unlikely to happen unless overlong tools are used.
Not so. I've taken many apart, which after removing the olive, show clear signs of the pipe being indented under where the olive was. And non of them leaked. If you've not seen this I'd say you have little experience.
If you follow the joints development, it would have been used with hemp amd mate, which is just PTFE's father, if it was intended to have such capacity. As you say, it was designed as a mechanical joint where a harder metal was used to deform a softer one to fill calculated gaps. Any other use is just misuse for convenience sake.
You did not tighten it enough for 15mm pipe if you tighten the nut as much as you can by hand and then tighten by a further 3/4 of a complete turn if it should weep you can tighten by another 1/8 turn Beware of being told that you cannot over tighten compression fittings thats a guaranteed way of making them leak PTFE can be used on the threads but never on the olive
you are not the only one to have done this
Why? PTFE tape in practice is little different from a sealing compound. It may not be necessary, but just what harm does it do?
Interesting Andy. In the blurb it said to make sure the copper pipe was spotlessly clean and without visible flaws.
I've seated the new pump in a plastic tray so that I can catch any slight leaks. If it does nothing else then at least it ought to alert me of a problem. Next trick is to add a liquid sensor into the tray to ring some sort of audible alarm.
Mungo
The message from "." contains these words:
If I show you a bit of copper pipe with a narrow neck in it, would you say that was deformed?
'Cos that's what it looks like if you cut the olive off after taking apart a correctly assembled compression joint.
turns. Seems more likely than the less than one turn or so spouted on here.
On Tue, 09 May 2006 19:32:54 +0100 someone who may be "Dave Plowman (News)" wrote this:-
I turn them until they feel right to me and have yet to have one fail spectacularly. I have had to tighten the odd one up a little more though.
I know it is tempting fate to type that:-)
I've happily used PTFE on olives in the past as well, but I can see how it might not create a perfect seal. Unlikely a sealing compound, PTFE isn't liquid, and so there's a chance that as you tighten the joint, the PTFE will rip and you'll end up with PTFE around most of the olive, but with a gap somewhere that could allow a small leak.
How likely that is, on the other hand, is a different matter!
G.
So no different from a paste, etc? That will also rub off from high spots.
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