6903 - Other refractory ceramic goods (for example, retorts, crucibles, muffles, nozzles, plugs, supports, cupels, tubes, pipes, sheaths, rods and slide gates), other than those of siliceous fossil meals or of similar siliceous earths:

HTS Code 6903 encompasses "Other refractory ceramic goods," which are specialized ceramic articles designed to withstand high temperatures and harsh chemical environments. This category includes a broad range of items such as retorts, crucibles, muffles, nozzles, plugs, supports, cupels, tubes, pipes, sheaths, rods, and slide gates. The defining characteristic is their refractory nature, meaning they are used in high-temperature industrial processes, chemical reactions, or as protective components.

This classification is distinct from other HTS categories within Chapter 69, which deal with different types of ceramic products. For instance, it differs from ceramic building materials (Chapter 69, Subheading II), tableware and kitchenware (Chapter 69, Subheading III), and ornamental ceramic articles (Chapter 69, Subheading IV). The primary differentiator for 6903 lies in the specialized function and material properties required for refractory applications, setting it apart from more general ceramic goods.

Within HTS 6903, further subdivisions are made based on the material composition of these refractory ceramics. Subheadings differentiate goods based on their percentage of free carbon (6903.10), alumina or a mixture of alumina and silica (6903.20), or other compositions falling under the general "Other" category (6903.90). These distinctions are critical for customs purposes, as the specific materials used in refractory ceramics significantly impact their performance and, consequently, their tariff classification.