On 11/11/2019 23:41, John wrote:

I can't see that will make any significant difference. The nut will
tend to compress the back of the olive and also drive it into the gap
between fitting and pipe which compresses the front of it. The forces
on both sides will be largely similar and in balance. From a sealing
point of view its the front face that's closing the gap between pipe
and fitting that is doing the work anyway.



...but the front of the olive can only close up if it can slide further
down the pipe.

A new olive will slide down the pipe easily - its the process of forcing
it into the socket on the fitting that results in the compression onto
the pipe, by which time its already in the right place.

To be fair, this is not a suggestion I have heard in the past, and so
have never tried doing it intentionally, but then again I have not had
any difficulty making successful compression joints in the vast majority
cf cases either.

While I accept that having a slight withdrawal of the pipe (oh err!) is
unlikely have any deleterious effect in most cases, I would also note
that it is contrary to the manufacturers instructions, which normally
stipulate that the pipe should be hard against the end stop. E.g.

http://www.pegleryorkshire.co.uk/MED...te_600_900.pdf

(see 1a)

or

http://www.conexbanninger.com/upload...14088edb0e.pdf

See section 2.1.3


--
Cheers,

John.

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