8109.31.00.00 - Containing less than 1 part hafnium to 500 parts zirconium by weight

This HTS category, 8109.31.00.00, specifically covers waste and scrap of zirconium that contains a very low proportion of hafnium. The defining characteristic for classification under this subheading is the weight ratio of hafnium to zirconium, which must be less than 1 part hafnium for every 500 parts zirconium. This stringent ratio ensures that the material is predominantly zirconium, with hafnium present only as a trace impurity.

The distinction between this category and its sibling, 8109.39.00.00 (Other), lies solely in the hafnium content. While both subheadings pertain to zirconium waste and scrap, 8109.39.00.00 encompasses all other zirconium waste and scrap that *does not* meet the precise low hafnium content requirement of 8109.31.00.00. Therefore, any zirconium waste or scrap exceeding the 1:500 hafnium to zirconium ratio would be classified under the "Other" subheading.

As this is a leaf node in the HTS classification system, there are no further subcategories to explore. Classification decisions for goods falling under this heading will therefore hinge on the precise determination of the hafnium content relative to zirconium, often requiring laboratory analysis to confirm adherence to the specified weight ratio.