Section 15 BASE METALS AND ARTICLES OF BASE METAL 73 ARTICLES OF IRON OR STEEL 73 05 406.4 MM, OF IRON OR STEEL. 73 05 90 OTHER TUBES & PIPES, EXT. DIAMETER>406.4MM,OF IRON/STEEL Commodity Code Description 73 05 90 00 OTHER TUBES & PIPES, EXT. DIAMETER>406.4MM,OF IRON/STEEL