"TeamCasa" writes:

I would suggest black pipe, create a "drip leg" with a drain at ever end or
connection. Make sure it is installed is such a way that water could not
stand anywhere. Imagine pouring in water at one end and it draining
completely.

My design has a drip leg at every outlet. The main line is about 25 feet
and I plan to have about 4" of slope.

My plan was to have a drip leg at the end of the main line, but that would
mean water could collect at the end of the main line where my elbow going
up would be. I better change things so I can drain the main line.

Brian Elfert