20 Valves of plastics, not including machine elements; handles for valves of plastics; automatic control valves of plastics, other than machine elements; corks, plastics and wooden stoppers; plastic and wooden lids; reservoirs, not of metal nor of masonry; storage tanks, not of metal nor of masonry; tanks, not of metal nor of masonry; liquid storage tanks or reservoirs, not of metal nor of masonry; industrial water storage tanks, not of metal nor of masonry; nuts and bolts, not of metal; washers, not of metal, not of rubber or vulcanized fiber; clamps of plastics