Without getting up close, I can't say for sure, but it doesn't look like intumescent paint nor does it look like a finish coat. It seems like a shop-applied corrosion-inhibiting primer in grey (whereas it's usually in a red oxide color). This will probably be given a white finish coat in the field once the erection is complete.unfamiliar with the necessity to paint some of this steel white... assuming some sort of anti-corrosive purpose, but why? I think this steel is "inside" the structure when fully built.