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 39 OTHER TUBES & PIPES, EXT.DIAMETER>406.4MM, WELDED, OF IRON/STEEL Commodity Code Description 73 05 39 00 OTHER TUBES & PIPES, EXT.DIAMETER>406.4MM, WELDED, OF IRON/STEEL