I'm not familiar with the "drap" verbiage. If the plant you visited had smelters for steel it was mostly likely a large integrated mill and you were in the melt shop/LMF section. I think ATI (stainless sheet) has or had a plant in Midland, PA.

Continuous hot-dipped galvanizing lines are smaller in comparison. If the plant you visited had a pot/kettle that they were feeding zinc ingots into then it was a HDG line.