" Actually, Galvanized IS NOT the material of choice. It is also not recommended for natural gas or propane. Main reason is the the galvanized make flake off and plug regulators, filters, lubricators, tools, and prevent them from closing."
Thats a myth ... we use galvanized pipe for NYC Transit, NJ Transit, Drug Companies for std compressed air as always with a filter at the discharge location. I have been installing it for 28 years and have yet to take apart a galavanized pipe to see flaking. I can tell you for sure I have found flaking inside Steel Pipe all the time ... copper is the best but too exspensive and Stainless would be the best but again cost is a factor.
The biggest issue is the system technique is 90% of the time pipe wrong ... the trunk line should be run pitched back to the compressor and the branches are to be teees faced UP and branch pipe taken off the tiop and dropped down the wall. Eliminates a lot of moisture problems.
In any case standing water is a non issue so pipe corrosion would be eliminated if pipe propoerly.
Ron