Redeye wrote:
after a rather more eventful weekend than i was hoping for, i'm hoping
somebody can explain this....

i finished plumbing in everything in my new bathroom a couple of weeks
ago. no real problems and all went quite well. so, i was a bit
surprised to be woken at 1am on saturday to the sound of water running
and a hysterical girlfriend. it appears that one of the compression
joints has spontaneously exploded, allowing mains pressure water to go
everywhere. fortunately no real damage done, just a lot of mopping up
to do downstairs.

the bit i don't understand is why this joint went so suddenly. here's
the facts :

1. the pipe had just slipped straight out leaving the olive in the
service valve that the pipe had escaped from.
snip
i'd quite like to understand why this joint has failed so spectacularly
before i go trying to fix it.

Because you diddn't tighten it up enough.
The olive should form a tight metal-metal seal, with no need for PTFE.
The only case where PTFE is actually needed is if you've got damaged
pipework, or fittings, and can't really replace easily.

You should _NOT_ be able to 'pull' the pipe out as happened in this
case, without actually damaging the fitting, and exerting much, much
more force than it saw.