primary aluminum smelter machinery and accessories, namely, potroom equipment, namely, pot tending machines, transfer gantry, lifting beams, retractable buffers, cathode cranes, anode jacking frames, anode rod clamps, and rails; crucible cleaning equipment, namely, crucible cleaning machines, tube cleaning machines, dross conveyors, and dedusting systems; carbon baking equipment, namely, furnace tending machines, green/baked anode stacking machines, fluewell demolition equipment, fluewall cle...