6 Pipes made primarily of steel; pipe fittings made primarily of steel, namely, flanges, flanged elbows, flanged tees, flanged crosses, instrument tees, gauge connectors, reducing flanges, sight indicators, blind flanges, expansion joints, vacuum expansion joints, spectal blinds, dip pipes, hoses, washers, contact rings, spray shields for flange connections, expansion joints and valves, valves, vessels and columns