"Jim Wilkins" fired this volley in news:mn7cqm$2di
:

Here is the relevant corrosion mechanism those articles omitted:
https://en.wikipedia.org/wiki/Concentration_cell
"Concentration cell corrosion occurs when two or more areas of a metal
surface are in contact with different concentrations of the same
solution."


Jim,
First, the phenonemnon you're referring to almost never happens in a
'mixing' environment. Second, the degree of 'concentration' must be
significant -- not horribly high, but higher than what you'd get from
differences in the stream in a well.

Third... nah... not in a well. You don't see those sorts of things going
on in a water well intended for human consumption.

This case is pure-and-simple mechanical abrasion from particulates. I'll
bet there's a 4' deep 'sand pack' in that lift pipe before it turns on,
which gets veritably BLASTED against the side of the pipe for a second or
two every time the them pump comes on.

Lloyd