Well, here in South Dakota there is almost no codes for gas lines. You can do almost anything you want. Just make it work and look good. Only the bigger cities require the gas lines to be grounded. That's about it for codes And I avoid black pipe if I can.
Why would Galvanized piping be prohibited? Is there a hazard? I've never heard of that. And I did it in my house because I don't want them to rust. My basement is quite humid in the spring and summer.
I was always told that you don't want to use galvanized on gas line because the galvanizing can flake off and plug an orifice...but recently someone that should know about these things told me that back in the day it was done to keep people from mixing up what pipes are for what...black pipe is gas, galvanized was water line. That sounds more likely to me.
Yeah, flaking off is what I learned also. And, the sulfur added to the gas can break down the zinc coating leading to corrosion
