In the perspective of vintage machinery, engines as for example, when original in most cases any plumbing with bends was usually black pipe and for that matter wrought iron pipe commonly used in early engines should be worked hot as opposed to steel cold or hot, generally in the vintage machinery gal if used at all in any length it was in straight runs, in this example of a original Austral with a known history it has no gal and few bends if any, many good restorations are ruined by the incorrect fitting of galvanized pipe... of course, just my opinion for what its worth ....... should really do some work on that Austral soon and get it running.