assuming it is galvanic attack, one needs to know which is the anode.  the
stud or ...?

in the case of pipes in the ground i recall from explanation by a power
engineer i work with that the underground pipe is biased w/ a low voltage
(~1Vdc) to make the pipe the cathode.  That way it plates up instead of
being the sacrificial element and plating out into the earth.

dwight

 At 5:55 PM 5/8/96, Maher, Steve (SD-MS) wrote:
>>> I propose a ground strap at least, from head to cylinder body,
>>>neutralizing any electrical imbalance. If nothing else it seems to me
>>>it would cause pitting around elect. connection.
>>
>>I think this trick works only if the current flows in the right direction.
>>Saltwater boats use it to protect their propellors etc. from galvanic
>>corrosion (not from chemical saltwater corrosion as I recall). A current
>>does inhibit galvanic action... but a current in the wrong direction
>>*accelerates* the galvanic corrosion!
>
>Basic point was, I have a hunch that a simple ground strap from heads
>to cylinder, wouldn't help, and might even hurt, by promoting current
>flow in the wrong direction. Maybe if you could somehow put a battery
>and resistor, in a circuit including the head and cylinder (if those
>two are indeed isolated), and so created an electrical potential in the
>right direction between head and cylinder, then it might have some positive
>effect (no pun intended) (well, not much).
>
>Any physical chemists out there? They would know far more about the
>validity of this effect, if any. Of course, I think my 6-year-old son
>also knows more than I about galvanic corrosion sometimes...  :-\
>
>    _______
>   /\ o o o\         Steve Maher   smaher@gi.com   75461,1717
>  /o \ o o o\_______   San Diego, California
> <    >------>   o /|
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