It's not galvanized and there is no yellow smoke. Not every weld to that pipe produces that green stuff. There were no noxious odors, either. It has me stumped.
I've gassed myself cutting and welding galvanized, before. It's not something I would forget. First time it ever happened, I thought I'd die. An old, experienced weldor handed me a quart box of milk and told me to drink it all. I felt human again about half-way through it. That was from cutting galvanized floor panels with a torch inside a grain bin. Really dumb. Had yellow and white fuzzies around every cut.