On Sun, 16 Mar 2008 12:22:30 -0700 (PDT), Carl M
wrote:

I have a 3/4" pipe thread hole in an aluminum plate, and I need
to be able to connect to both sides of it using pipe fittings, with
the through bore size not so critical. I have been looking around the
web trying to find out what to call a double sided reducing bushing,
but so far no luck. Short of having one made, I'm wondering if anyone
has had this problem before and what you did about it. FWIW, the
fittings would hopefully be stainless, but there's no serious need for
it other than everything else in the system is.
Thanks!
I use a half of a 1/4 pipe coupling, turned down to fit the bored out
inner end of a 3/4 - 1/4 reducing bushing. Silver solder the two
pieces together and you have your fitting. I made a couple of these to
adapt propane tanks for my compressor.
Gerry :-)}
London, Canada