(A) GASKETS AND SIMILAR JOINTS OF METAL SHEETING COMBINED WITH OTHER MATERIAL OR OF TWO OR MORE LAYERS OF METAL
These are composed of :(¥¡) A core of asbestos (or sometimes felt, cardboard or other non-metallic material) sandwiched between two metal sheets. or (¥¢) Asbestos or other non-metallic materials cut to shape, and with metal sheeting folded along the outer edges and around the edges of any holes punched in the gasket or joint. or (¥£) Layers or metal foil (of the same metal or of dissimilar metals) pressed together. They are mainly used in certain motors or pumps, or for certain pipe joints. But the heading excludes gaskets and joints of asbestos board reinforced with metal wire or metal gauze (heading 68.12), unless forming part of a set or assortment covered by the second part of this heading. (B) SETS OR ASSORTMENTS OF GASKETS AND SIMILAR JOINTS Such sets or assortments of any material (agglomerated cork, leather, rubber, textiles, paperboard, asbestos, etc.) are classified here when put up in pouches, envelopes, boxes, etc., provided that the gaskets or joints are not all of the same material. To be classified here, the sets and assortments must contain at least two gaskets or joints of different material. Therefore a pouch, envelope, box, etc., containing, for example, five gaskets all made of paperboard, is not covered by the heading but is classified in heading 48.23; but if the set also included a rubber gasket it would fall in this heading. (C) MECHANICAL SEALS Mechanical seals (e.g., sliding-ring seals and spring-ring seals) constitute mechanical assemblies which form a leakproof joint between flat, rotating surfaces to prevent high-pressure leakage in the machine or apparatus on which they are mounted, resisting the pressure and stress exerted on them by moving components or due to vibrations, etc. The structure of these seals is generally fairly complex. They comprise : (¥¡) fixed parts which, when the seal is placed, become integral with the machine or apparatus; and (¥¢) movable parts : rotating elements, spring elements, etc. It is specifically on account of these movable parts that the articles are called "mechanical seals". These seals act as anti-vibration devices, bearings, actual seals and, in some cases, as unions. These seals have numerous applications, including in pumps, compressors, mixers, agitators and turbines; they are produced from a variety of materials and in various configurations. The heading does not cover : (a) Gaskets or joints, other than the composite types incorporating metal sheeting or foil, which do not comply with the conditions set out in (B) above; these are generally classified according to their constituent material. (b) Machinery packing (e.g., of asbestos cord heading 68.12). (c) Oil seal rings of heading 84.87.
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