Bundyweld piping OK?

Went through a home built in (Colorado) '73 and found pipes that looked like a cross between copper and galvanized. Sorry no photos now. Couldn’t figure out what it was and finally an old plumber told me it was “Bundyweld” and that it was fine.

Couldn’t find any problems that seemed to relate to the material, so I guess he was right. Anybody know anything abouthis stuff?