Exceeding 8 inch inner dia

73.04 Tubes, pipes and hollow profiles, seamless, of iron (other than cast iron) or steel (+). - Line pipe of a kind used for oil or gas pipelines : 7304.1 1 - - Of stainless steel 7304.19 - - Other - Casing, tubing and drill pipe, of a kind used in drilling for oil or gas : 7304.22 - - Drill pipe of stainless steel 7304.23 - - Other drill pipe 7304.24 - - Other, of stainless steel 7304.29 - - Other - Other, of circular cross-section, of iron or non-alloy steel : 7304.31 - - Cold-drawn or cold-rolled (cold-reduced) 7304.39 - - Other - Other, of circular cross-section, of stainless steel : 7304.41 - - Cold-drawn or cold-rolled (cold-reduced) 7304.49 - - Other - Other, of circular cross-section, of other alloy steel : 7304.51 - - Cold-drawn or cold-rolled (cold-reduced) 7304.59 - - Other 7304.90 - Other Tubes, pipes and hollow profiles of this heading may be manufactured by the following processes : (A) Hot-rolling of an intermediate product, which can be either an ingot, rolled and peeled, a billet or a round obtained by rolling or continuous casting. This process of manufacture includes : (1) Piercing in a cross rolling mill (Mannesmann rocess), in a disc mill or in a cone iercer to obtain a hollow blank of greater w 1 thickness and outside diameter an% pesser length than the final product. (2) Hot-rolling upon a mandrel or a plug : - in a three slanted rolls elongator (Assel or Transval) used in ma or part for the mufacture of bearing tubes or a two slanted rolls elongator wi guiding discs (Diescher process) or a three slanted planetary elongator or B - in a " continuous tube rolling mill " having different sets of rolls upon a " free floating " or semi-floating restrained mandrel (Neuval or Dalmine process) or - in a pilger mill or - in a Stiefel mill or - in a push bench by pushing the blank in a series of rolls or - in a stretch reducing mill. In this case the product obtained is a finished tube. (B) Hot-extrusion in a ress using lass (Ugine-Sejournet process) or another lubricant, of a round. This metho actually inc udes the following operations : piercing, expansion or not, and extrusion. d B The operations described above are followed by different finishing operations : - hot-finishing : in this case, the blank after reheating passes through a sizing mill or a stretching mill and finally a straightening mill or cold-finishing on a mandrel, by cold-drawin on a bench or cold-rolling (cold-reducin ) in a pilger mill (Mannesmann or egaval process . These operations 've the possi ility to obtain fiom hot-rolled or extruded tubes, use as blanks, tubes of gsser wall thickness (it should be noted that the T r m l process allows tubes of reduced wall thickness to be directly produced) or diameter, also tubes of tighter tolerances on diameter or wall thickness. Cold-working methods also cover honing and roller burnishing to obtain polished surfaces (tubes with a low degree of roughness) required, e.g., for pneumatic jacks or hydraulic cylinders. d t d (C) Casting or centrifugal casting. (D) Deep drawin of a disc placed over a forming mould, the blank produced being subsequently ot-drawn. i? (E) Forging. (F) Machining of bars followed by cold-drawin or cold-rolling (cold-reducing) operations (excluding hollow drill bars of herding 72.287, See the Genera1 Explanatory Note to this Cha ter concerning the distinction between tubes and pipes on the one hand and hollow profiles on &e other. The products of this heading may be coated, for example, with plastics or with glass wool combined with bitumen. This headin also covers finned or gilled tubes or pi es and hollow profiles such as integrally finned or gil ed tubes with longitudinal or transversal ins. t! The products of this heading include, in articular, line pipes of a kind used for oil or gas, casing, tubing and drill pipes of a kind use in drilling for oil or gas, tubes and ipes suitable for use in boilers, superheaters, heat exchan condensers, refinmng furnaces, eedwater heaters for power stations, galvanised or black gas tubes) for high or medium pressure well as tubes for water or gas street steam, or gas or water distribution distribution mains. In addition tubes and pi es are used for the manufacture of parts for automobiles or for machinery, of rin s for bal bearings, cylindrical, tapered or needle bearings or for other mechanical uses, for sca olding, tubular structures or buildmg construction. f I P f The heading excludes : (a) Tubes and pipes of cast iron (heading 73.03) and tubes and pipes of iron or steel of heading 73.05 or 73.06. (b) Hollow profiles of cast iron (heading 73.03) and hollow profiles of iron or steel of heading 73.06. (c) Tube or pipe fittings of iron or steel (heading 73.07). (d) Flexible tubing of iron or steel with or without fittings (including thermostatic beIlows and expansion jolnts) (heading 83.07). (e) Insulated electrical conduit tubing (heading 85.47). (f) Tubes, pipes and hollow profiles made u into specific identifiable articles, e-g., those repared for use in structures (heading 73.08), tubuL sect~onsof central heating radiators (heaging 73.22), exhaust manifolds for internal combustion piston engines (headin 84.09), other machinery arts (Section XVI), exhaust boxes (silencers) and exhaust p~ es otvehicles of Chapter 87 remg., heading 87.08 or 87.14), saddle pillars and frames for cycles [heading 87.14).