In article ,
"Christian McArdle" writes:
I have noticed that all the drain valves I have seen for sale are
brass. Is it possible to solder these rather than using a compression
fitting?

Yes. Brass solders easily.

Clean up with steel wool and flux, just as you would copper.

Suggest you unscrew and remove the guts whilst soldering.
At least, I do, as I rather suspect the rubber parts will
not survive otherwise.

--
Andrew Gabriel