You must clean the both valve and the pipe.

You must flux both the valve and the pipe.

It can be soldered with a propane torch, but it will take longer than using
a MAPP gas torch.

--
Jim McLaughlin

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wrote in message
oups.com...
Thanks everybody for taking time to answer my question.
Here is how I did it:
First I used torch to heat the copper pipe and tried to remove residue
of remaining solder with a clean sock(as damp cloth), then I used emery
cloth and the other tool(cleaning tool with wire in it) to clean the
pipe joint. I can tell that the copper pipe is shiny after cleaning. I
am not sure whether I need to clean the fitting of newly bought brass
valve or not, should I? Next I applied the flux only to the copper pipe
source, then placed the brass valve. I don't have MAPP gas, only the
propane gas. I heated the fitting until I can hear the sizzling sound,
then I applied the solder.
If I use propane torch, how can I tell that time is right to apply
solder or in other word, when the fitting is hot enough to apply solder
using propane torch? Can propane torch generate enough heat for
solering brass valve?
Thx again.