Looking for anodized aluminum pipe

[cc]

I agree with pipedreams. As as fabricator, we build many aluminum objects from polished and unpolished material, weld it, and then have it anodized after fabrication. But if you are not worried about the material corroding in the heat affected zone (where you weld), you can weld over the anodic coating on preanodized material. The high frequency will clean the puddle while you weld.