Only if the dissimilar metal is left in place or left enough residue on the
copper to cause a reaction.
wrote in message
oups.com...

bent wrote:
I pulled some 1/2" copper pipes upward in the summer with wire for
clearance
in preparation for installing T-bar ceiling tiles. I don't know that it
did
any damage to the pipe or joint, or even if I have more than a common
situation now. I wrapped some pipe insulation, but not completely, this
joint in question was tough to get to, and I left it until I was ready to
finish it off. Today I was peeling back that same insulation; these
pipes
go to the sink and toilet in the basement washroom, and the last inch or
two
of the insulation was WET, meaning waters on the outside. Its been
months
since its been summer/humidity? in Toronto. I have taken off the
insulation, chiseled off the little black rotting part of 2x4", and
cleaned
off the pipes, but other than the moist insulation I haven't seen any
water
at all, even when running tissue paper around. The water may even been
wicking from down inside the 2x4" in the wall, a crack possibly on the
other
side of the elbow in the wall. . I don't know if either pipe is
dripping
from a leak/crack, or if the cold is condensing (its cold to the touch),
or
the insulation has just stayed wet since last it was humid, or if its
bound
to happen when I flush.. This pipe is at the end of the plumbing line,
nothing else runs past them. The basement is where the hot and cold
water
are, both at the other far end of the house. The place in question is in
the ceiling, running just under the first floor joists. More
specifically,
where both the hot and cold pipes have 90 degree elbows soldered, and
where
these pipes turn and go straight down into a stud wall. The drilled hole
in
the 2x4" top wall plate is just large enough to fit the hot and cold,
each
in individual holes, so nothing is getting/looking in there. The elbows
are
just barely solderable above this top 2x4", in fact the cold is
half-buried.
The two pipes are spaced diagonally, about 1" apart on centers; the pipes
run very close together, both along the ceiling, and in the wall. The
hot
pipe is the upper one. Where the hot elbow is soldered some of the
solder
of that joint is actually soldered to the upper length of straight pipe
of
the cold.

How do I diagnose if I have a leak? I have not run any hot or cold water
in
the sink, nor flushed the toilet in a couple days. In the last few
months I
have only flushed the toilet twice, both times in the last couple weeks.
I've just got tissue paper sitting there, waiting for me to look later. I
could drill a hole-saw in the wall, but what about running the water,
etc.
to help find out. A problem is its a tight location, can't see all
possibilities, and don't know how to check with a diagnosis. There are
more
pipes around, but they are all currently insulated.




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If you used a steel wire to pull up the pipe you may have created a
problem by contacting two dis-similar metals which can over time cause
the pipe and wire to rot out.