air lines, No Truimph content

[J&E <ebk@buffnet.net>]

Hi List!
        I do remember the thread some time ago reguarding air lines. the topic
was about plastic vs pipe. I've decided to go with galvanised pipe vs.
black pipe. 
        Question:
1- Am I making a mistake in chosing galvanized over black pipe?
2- What size inside diameter (ID) pipe is best?, 
2a- 1/2" too small?
        
        I was thinking of 1" pipe but that's going to be a chalange trying to
run it in between the floor joist, I think. Floor joist = 2"x6". TIA,
-Cosmo Kramer