Electrolysis And Dielectric Nipples

[LazyPup]

Here is an illustration that explains "Electrolysis" and how a "Dielectric Nipple" can prevent it.

[HayZee518]

your diagram is nice but you got the "water" drawn on the wrong side of the pipe.

[LazyPup]

The water is on the inside where it belongs

[Redwood]

My experience is a little different than the diagram shows.
The statement that a dielectric nipple helps prevent corrosion is correct.
A brass nipple at least 6" long will also do that.
But the metal that loses is not the copper. The galvanized pipe is the one that loses in the corrosion process.