Machine-part classification under Section XVI prevails for specially fabricated rupture discs used solely to protect an acid plant furnace.

Section Note 2 to Section XVI requires specially fabricated goods used solely or principally with a particular machine to be classified with that machine, subject to the note's exclusions and ordering rules. Rupture discs made for an acid plant combustion chamber, designed to burst at a specified pressure and perform an integral protective function, were treated as machine parts rather than as goods classified by their material of construction. The tribunal applied the functional character of the items and the earlier treatment of similar rupture discs to conclude that classification followed the machine-part rule. The goods were therefore placed under Heading 84.85.90 instead of the material-based heading adopted by the department.

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Issues: Whether rupture discs used in an acid plant, designed to burst at a specified pressure to protect the furnace from overheating, are to be classified as parts of machinery under Heading 84.17 or under the material-based heading proposed by the department.

Analysis: The classification of machine parts is governed by Section Note 2 to Section XVI, which requires that parts suitable for use solely or principally with a particular machine be classified with that machine, subject to the exclusions and the ordering rules in the note. The rupture discs were specially fabricated to fit the combustion chamber of the acid plant, were not supplied as ordinary sheets, and were meant to perform a protective function integral to the plant. The earlier tribunal decision relied upon by the appellant had already examined the same functional character of rupture discs and treated them as classifiable with the machinery they served. Applying that reasoning to the present goods, their essential character was determined by their function as a machine part rather than by the material of construction.

Conclusion: The rupture discs were correctly classifiable under Heading 84.85.90 and not under the material-based heading adopted in the impugned order.

Final Conclusion: The appellant succeeded and the goods were directed to be classified under Heading 84.85.90.

Ratio Decidendi: Where a specially fabricated item is designed for sole or principal use with a particular machine and performs an integral protective function, its tariff classification follows the machine-part rule in Section XVI rather than the material of construction.

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