"Ron Cliborn" wrote
I live in Zone 8 ( the zones for buying plants.) Out side of
Atlanta,GA. It gets cold in the winter, and we get a few days below
freezing, some snow, but not often. However, I'd like the pipe to be
able to survive a 20 or 50 year freeze.

Insulation alone will slow the laws of thermodynamics, but it does not
repeal them.

No matter what you do with insulation, eventually the heat will be lost and
the pipe will freeze. If you want to be 100% sure, you must either drain
the water or add heat. Wrap the pipe with heating tape and turn it on when
it gets below freezing. A frost prove valve will work as long as the pipe
drains where exposed.