In article ,
"Clive George" writes:
"repro" wrote in message
...
Is there a conventional way to join new 12mm copper pipes to old imperial
1/2" ?
Is the difference too small to worry about ?
Would compression be better than soldered?
Opinions/wisdom welcomed

(I'll assume you meant 15mm, not 12mm - metric are outside diameter,
imperial are inside IIRC)

And for a followup, putting fittings on a pipe which has been expanded by
frost.

(ans: get a solder fitting, press a suitably sized socket into it to make it
larger. Maybe do this in a couple of stages)

(of course this won't work if 1/2" pipe is smaller - I don't know...)

It is smaller. The difference is small enough that metric
fittings generally work on imperial 1/2" pipe. This is less
true for 3/4" where some form of adaptor is usually required
to 22mm.

--
Andrew Gabriel