I just have two comments based on 41 years of working in utility power plants. Copper piping is the material of choice for instrument air systems. Corrosion resistance is the primary reason. I worked in plants that were 40 years old at the time that still had the original copper instrument air systems in place. Galvanized was prohibited for instrument air. What happens is that over time the galvanizing would start disintegrating on the pipe interior. The debris would start plugging the instrumentation that the instrument air system fed. Just my view on this.
