6 Iron and steel; special steels; ordinary steels; steel pipes; steel tubes; steel sheets; rerolled steels; steel rails; steel angles for use in building construction; zinc-coated steel sheets; clad steel plates and sheets; hollow steel bars; tinplate; cold-finished steel bars; iron or steel scraps; alloy steel scraps; carbon steel scraps; low copper carbon-steel scraps; metal materials for building and construction; pilings of metal; water-pipes of metal; handrails of metal; pillars of metal for building; valves of metal, other than parts of machines; angle valves of metal, other than parts of machines; ball valves of metal, not machine elements; cocks of metal, not machine elements; automatic control valves of metal, not machine elements; butterfly valves of metal, not machine elements; junctions of metal for pipes; flanges of metal [collars]; metal hardware, not including "security locks, ring of metal for keys, keys of metal for locks and padlocks"; nuts of metal; bolts of metal; washers of metal