When tightening compression joints it always seems a bit kind-of hitand miss and they seem to need to be VERY tight to not leak - so tightI worry about damaging the joint or pipe.I normally put grease on the threads which makes them easier totighten but of course doesn't reduce the pressure on the parts..After fitting a radiator the screw cap had started to crack after itwas leaking a tiny bit and I tightened it some more. So I'm wonderingif I'm doing something wrong, perhaps the pipe should be pulled out alittle bit from the joint before tightening? or anything else?Also are the silver joints stronger than gold ones?

In my limited experience compression joints leak ifa) the pipe isn't 100% aligned with the fitting, i.e. approaching at a slight angle.b) the pipe isn't fully pushed into the fitting. Sometimes difficult to keep it pushed in when both hands are holding spanners.c) the cut isn't made with a proper pipe cutter

15mm Compression Joints pull the pipe out a bit before tightening?

Oct 11, 2008 27 Replies

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GMM 17 years ago

I've never really looked at it systematically but I wonder whether some olives are better than others, where 'better' might be 'softer', so more likely to seat in the fitting. I just did a complicated little run that I built up on the bench (fresh pipe, no alignment issues, plenty of access to tighten everything) then installed and it leaked in about half the joints. Took it off and recycled most of the pipe and all of the fittings but, obviously, had to use fresh olives - every joint was a good 'un. If I knew where I got that pack of olives (probably Screwfix), I'd get some more while they're still on the same batch!

On the other hand, it might have been a 'good day/bad day' thing and nothing to do with the olives......

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Huge 17 years ago

Accoridng to what I've read, and subsequent experience, a 1/4 to half turn at the outside.

I suspect the OP is over-tightening them.

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Huge 17 years ago

Could be. I always do.

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Dave Plowman (News) 17 years ago

I've seen fittings with damage to the tapers. Dunno how much the BS majors on quality control.

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RobertL 17 years ago

=A0 London SW

when cleaning the tube I use steel wool and a rub it 'round and round' rather than 'up and down' so there are no 'channels' scratched into the tube surface. Much as if I was doing a soldered joint. perhaps this is overkill.

Robert

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Dave Plowman (News) 17 years ago

Just for information you can get cleaner strips these days that are faster than wire wool - and no sharp bits to pierce the skin. They seem quite expensive - but have a long life. I won't use anything else now. Also makes cleaning the back of a pipe in a tricky place easy.

However neither method should produce scratches deep enough to cause problems - and 'round' the pipe is the natural way to clean it.

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The Medway Handyman 17 years ago

I also clean the pipe prior to using a compression fitting, don't think its overkill at all.

I use those & find them really good, if the end of the pipe is accessable I use one of these

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Appin 17 years ago

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Conex ones are particularly good, IMHO

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