73.03 Tubes, pipes and hollow profiles, of cast iron.
This heading applies to tubes, pipes and hollow profiles manufactured of cast iron as defined in Note 1 to this Chapter. They may be manufactured by casting in moulds or by centrifugal casting; in the latter case, the molten iron is poured into a horizontal cylinder which is rapidly rotated so that the metal is forced centrifugally against the walls where it solidifies. These tubes, pipes and hollow profiles may be straight or curved, plain, finned or gilled. They may be socketed, flanged integrally or flanged by welding or threading. To facilitate assembly, socketed pipes have one end expanded to receive the end of a second pipe. Flanged pipes can be assembled by means of collars, nuts, bolts, clamps, etc., while threaded or plain end pipes are assembled by means of couplings, rings or collars. This heading also covers tubes, pipes and hollow profiles with multiple or branch openings, and those which are covered, for example, with zinc, plastics, bitumen. Tubes and pipes of this heading are mainly used for pressure or gravity pipelines for water, sewer evacuation, for low pressure gas distribution, as gutter or drain pipes or for drainage. The heading does not cover :(a) Tube or pipe fittings (heading 73.07). (b) Tubes, pipes and hollow profiles made up into identifiable parts of articles, classified in their respective headings, such as sections of central heating radiators (heading 73.22) and machinery parts (Section XVI).
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