The best approach is to remove the galvanize coating from the weld joint and at least 1/2 inch from the anticipated toe of the weld. You can wet the work piece with water after galvanize removal and let it sit overnight. If the piece isn't completely cleaned, it will be apparent by the absence of a light blush of "rust". Reclean the piece if there are any areas without rust.
A belt sander works nicely. It doesn't load up with zinc as does a regular aluminum oxide grinding disk.
Good luck - Al
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