2710.20.10.50 - Having a Saybolt Universal viscosity at 37.8˚C of more than 125 seconds (heavy fuel oils)

This HTS classification specifically covers heavy fuel oils, which are characterized by their high viscosity. The defining criterion for this category is a Saybolt Universal viscosity at 37.8°C exceeding 125 seconds. These oils are typically derived from petroleum or bituminous minerals and are generally used as fuel in large industrial furnaces, marine engines, and other heavy machinery where a less volatile and more viscous fuel is required.

It is important to distinguish this category from its siblings. Lighter fuel oils, classified under a different subheading, have a Saybolt Universal viscosity of less than 45 seconds. Intermediate fuel oils, often referred to as No. 4-type fuel oils, fall into a middle range, with viscosities of 45 seconds or more but not exceeding 125 seconds. This specific classification, therefore, targets only the heaviest end of the fuel oil spectrum.

As this is a leaf node in the HTS structure, there are no further subcategories. Products classified here are defined by their specific viscosity measurement and their intended use as heavy fuel oil. Classification decisions at this level will hinge on precise laboratory testing of the product's viscosity against the established threshold.