Is there any reference on the internet about temperatures and durations that
are required to freeze pipes?

Every year I get neurotic when they start having frost advisories about my
cottage. I know it takes hours to freeze ice cubes at 0 degrees, so it
obviously takes more than a few hours at 30 degrees to freeze pipes; but
some actual data would be nice.

It is a big chore to shut off the water, and then I am without water until
next Spring.