What does your engineering drawing say about welding & steel coatings also are you building coastal (near the beach)?
The rust is superficial (but may be an issue) and should be re-touched (up) with a primer
Thanks for your reply SBG!
The builder picked it up too, and will clean it and then paint an epoxy paint over it to stop the rust.
He said that its just surface rust, we are not coastal.
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