If you are talking about the change in color where the fittings are welded, that is normal since the welding process changes the aluminum structure. Different aluminum alloys and different hardnesses take color differently.....you will always see the welds.

Anodize is about one thousdanth of an inch thick (0.001"). Type II scratches off relatively easily. ALuminum oxidizes (rusts) within 15 minutes of being scratched but it rusts in aluminum color...not red or blue so it is noticeable.