When tightening compression joints it always seems a bit kind-of hit
and miss and they seem to need to be VERY tight to not leak - so tight
I worry about damaging the joint or pipe.

I normally put grease on the threads which makes them easier to
tighten but of course doesn't reduce the pressure on the parts..

After fitting a radiator the screw cap had started to crack after it
was leaking a tiny bit and I tightened it some more. So I'm wondering
if I'm doing something wrong, perhaps the pipe should be pulled out a
little bit from the joint before tightening? or anything else?

Also are the silver joints stronger than gold ones?

405 TD Estate wrote:
When tightening compression joints it always seems a bit kind-of hit
and miss and they seem to need to be VERY tight to not leak - so tight
I worry about damaging the joint or pipe.

I normally put grease on the threads which makes them easier to
tighten but of course doesn't reduce the pressure on the parts..

After fitting a radiator the screw cap had started to crack after it
was leaking a tiny bit and I tightened it some more. So I'm wondering
if I'm doing something wrong, perhaps the pipe should be pulled out a
little 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 if

a) 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

stuart noble wrote:
405 TD Estate wrote:
When tightening compression joints it always seems a bit kind-of hit
and miss and they seem to need to be VERY tight to not leak - so
tight I worry about damaging the joint or pipe.

I normally put grease on the threads which makes them easier to
tighten but of course doesn't reduce the pressure on the parts..

After fitting a radiator the screw cap had started to crack after it
was leaking a tiny bit and I tightened it some more. So I'm wondering
if I'm doing something wrong, perhaps the pipe should be pulled out a
little 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 if

a) 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

I'd totally agee with Stuart. Given you heed his advise above, they don't
need to be as tight as you describe to seal.


--
Dave - The Medway Handyman
www.medwayhandyman.co.uk

On Sat, 11 Oct 2008 18:47:15 +0000, The Medway Handyman wrote:

stuart noble wrote:
405 TD Estate wrote:
When tightening compression joints it always seems a bit kind-of hit
and miss and they seem to need to be VERY tight to not leak - so tight
I worry about damaging the joint or pipe.

I normally put grease on the threads which makes them easier to
tighten but of course doesn't reduce the pressure on the parts..

After fitting a radiator the screw cap had started to crack after it
was leaking a tiny bit and I tightened it some more. So I'm wondering
if I'm doing something wrong, perhaps the pipe should be pulled out a
little 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 if

a) 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

I'd totally agee with Stuart. Given you heed his advise above, they
don't need to be as tight as you describe to seal.

Agreed, a tiny smear of a suitable jointing compound also help a lot.


--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at http://www.diyfaq.org.uk
Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html
Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html
Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html

Jointing compound - on the olive or threads?

"Ed Sirett" wrote in message
...
On Sat, 11 Oct 2008 18:47:15 +0000, The Medway Handyman wrote:

stuart noble wrote:
405 TD Estate wrote:
When tightening compression joints it always seems a bit kind-of hit
and miss and they seem to need to be VERY tight to not leak - so tight
I worry about damaging the joint or pipe.

I normally put grease on the threads which makes them easier to
tighten but of course doesn't reduce the pressure on the parts..

After fitting a radiator the screw cap had started to crack after it
was leaking a tiny bit and I tightened it some more. So I'm wondering
if I'm doing something wrong, perhaps the pipe should be pulled out a
little 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 if

a) 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

I'd totally agee with Stuart. Given you heed his advise above, they
don't need to be as tight as you describe to seal.

Agreed, too.

To add some mo

The pipe ought to be clean, free from scratches / gouges, and properly
round.
The olive ought to be able to slide up and down freely, but not loosely.

With the pipe in the fitting, it ought to be possible to do up the nut right
up to the olive by hand. It should then only take a gentle nip up with a
spanner.


Problems can be:
Over-tightening in the first instance ( a possibility from your
description );
Poor condition pipe ( deeply scratched, painted, ovaled out from mis-use or
impropper cutting ).
Pipe entering at an angle as already mentioned. Allow the pipe to be as
free to move side-ways as possible, so it can find a natural alignment.

If you want to use any sealing compound, it ought to go on the sealing
element ( the olive ) rather than the thread. The thread is not the
sealing element in a compression fitting.


--
Ron

If you want to use any sealing compound, it ought to go on the sealing
element ( the olive ) rather than the thread. The thread is not the
sealing element in a compression fitting.


But some lubrication on the thread always helps too, especially on some
fittings where the thread seems to be a bit "rough".
I usually put a smear of compound under and on the olive, then on the
thread.

A

We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "Ron Lowe"
ronATlowe-famlyDOTmeDOTukSPURIOUS saying something like:

With the pipe in the fitting, it ought to be possible to do up the nut right
up to the olive by hand. It should then only take a gentle nip up with a
spanner.

Depends what you mean by that. Your 'gentle nip up' might actually mean
a good quarter turn or more. Most people's 'nip up' would leave it prone
to loosening off.
--
Dave
GS850x2 XS650 SE6a

"It's a moron working with power tools.
How much more suspenseful can you get?"
- House

In article
,
405 TD Estate wrote:
When tightening compression joints it always seems a bit kind-of hit
and miss and they seem to need to be VERY tight to not leak - so tight
I worry about damaging the joint or pipe.

I normally put grease on the threads which makes them easier to
tighten but of course doesn't reduce the pressure on the parts..

After fitting a radiator the screw cap had started to crack after it
was leaking a tiny bit and I tightened it some more. So I'm wondering
if I'm doing something wrong, perhaps the pipe should be pulled out a
little bit from the joint before tightening? or anything else?

You must be using enormous torque to damage a 15mm compression fitting.

If you have leaks after normal tightening, something is wrong.

Is the pipe clean, round, straight and free from bad scratches?
Is it going fully into the fitting?
Are you using good quality fittings?

A lick of Fernox LS-X silicone sealer round the olive before tightening
won't harm - but really shouldn't be needed.

--
*Honk if you love peace and quiet*

Dave Plowman London SW
To e-mail, change noise into sound.