Section 15 Base metals and articles of base metal 73 Articles of iron or steel 73 08 Iron/steel structures and parts thereof; plates, rods... therefor,....of iron or steel Commodity Code Description 73 08 10 Bridges and bridge-sections 73 08 20 Towers and lattice masts 73 08 30 Doors,windows and their frames and thresholds for doors 73 08 40 Equipment for scaffolding, shuttering, propping or pit propping 73 08 90 Angles, profiles perforated, prepared for use in the assembly of metal structure