In article ,
"Roger Mills" writes:

Yes. One end of one or two of the isolator valves were on 3/4" pipe - for
which I used the proper 3/4" imperial olives. But the problems to which I
initially referred were with brand new 22mm copper pipe, using the 22mm
olives supplied with the fittings.

They do need quite a lot of force (possibly more so for brass
olives than copper olives). For 22mm compression joints, I put
a couple of turns of PTFE on the thread and on the rear half
of the olive to act as a lubricant whilst tightening, but I'm
very careful not to get it into any of the sealing surfaces.
(If you disassemble again before final assembly, you can take
the PTFE off once the olive is deformed onto the pipe.)

I found it also made a big difference having spanners which
are exactly the right size. On 15mm, I had written off a
couple of nuts using an adjustable spanner whose jaws were
perhaps not completely parallel due to give in the sliding
mechanism. The spanner managed to squish the nut into a
slight oval shape, which of course never managed to make a
seal.

I never use compression fittings except where I have to.
My preferred option is soldered fittings, but obviously
not usable or applicable in all cases.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]