Metallurgical (coking) coal is a critical input for blast-furnace steelmaking, and its trade flows are closely watched by steel producers and their suppliers. Unlike thermal coal used for power generation, coking coal commands a quality premium based on ash content, sulfur level, and coke strength — distinctions that also affect HTS classification at the tariff-line level.

LPG imports — propane, butane, and mixtures — are classified under HTS headings specific to their liquefied state and chemical composition, separate from gaseous natural gas. The physical form at the time of importation and the specific hydrocarbon mix determine the applicable tariff line, so laboratory analysis or supplier certification of composition is often required for accurate entry.