On Jan 12, 2:35*am, Richard Clark wrote:
On Mon, 11 Jan 2010 21:17:13 -0800 (PST), Tom Horne

wrote:
If I use a dielectric union for the joint and bond around it for
lightning safety will that solve the corrosion problem by preventing
direct contact between the two dissimilar metals or would the bonding
cause the same destructive current flow as the direct contact?

Hi Tom,

I don't know what you mean by bond that is both insulative to cathodic
action, and conductive to lightning. *To me, bonded metals don't
introduce a complaint of anticipated galling. *If they are bonded
(soldered, brazed, or welded), you don't expect to disconnect them and
suffer galling problems. *If they are soldered, brazed, or welded,
then the seam can still support cathodic action - it is simply a cell
loaded with the short of the bond if I read it that way.

I don't often find myself in your situation, so I have little to go on
beyond the common discussion. *I have had to deal with these issues
with fine measurement where it is always lingering and it often took
heroic effort (careful, this is hyperbole unless you have to make a
living at it) to succeed.

Jimmie may have something more to offer.

73's
Richard Clark, KB7QHC

All I know is I haven't had a problem with corrosion. Apparently the
brass is is similar enough to both copper and the galvanized steel or
maybe the rain here is not so corrosive, maybe its the anti-seize. I
actually cant say with certainty that if I connected the copper
directly to the galvanized pipe I would have had problems. Somewhere I
learned, possibly wrongly, you should join copper to galvanized
plumbing with brass.


Jimmie