Probably the best way to prevent galvanic corrosion is Bostik 'Never Seez', or Loctite Anti Seize compounds. These products are used in power plants, refineries, shipyards, and perform very well. Never Seez, the one I use, comes in several grades, the best and most expensive of which is "Pure Nickel Nuclear Grade". Once you have some on-hand, you'll find many uses for it, particularly since more and more products are being manufactured using pot metal and other less-expensive materials. Only a thin layer is needed—a little goes a long way. I've use it on automotive exhaust systems, and they're easy to disassemble years afterward.
This is a timely article (and reminder) for me, because I just put a Dramm aluminum hose end shut-off in service the other day, and I forgot to put Never Seez on the threads. It probably slipped my mind because I usually buy Dramm's brass shut-offs. In retrospect, the aluminum one wasn't worth the couple of dollars I saved on it.
They have lasted me for years, and in the winter months they are taken off and stored. I don't know about over your side of the pond, but brass fittings of any kind are very expensive. But a brilliant article.
