7304.59.20.40 - Having an outside diameter less than 38.1 mm

This HTS category, 7304.59.20.40, encompasses seamless tubes and pipes of iron or steel, specifically those of other alloy steel with a circular cross-section, that are not designed for use in boilers, superheaters, heat exchangers, condensers, refining furnaces, or feedwater heaters. The defining characteristic of this classification is an outside diameter strictly less than 38.1 mm. This criterion is critical for distinguishing these smaller diameter tubes from those intended for more specialized industrial applications.

Distinction from sibling categories at this level is primarily based on the specified outside diameter. For instance, 7304.59.20.45 covers tubes with an outside diameter of 38.1 mm or more but not exceeding 114.3 mm, while 7304.59.20.55 applies to tubes exceeding 114.3 mm but less than 190.5 mm. This ensures that tubes are accurately categorized based on their precise physical dimensions, preventing misclassification due to minor variations.

As this is a leaf node in the HTS database, there are no further subcategories within 7304.59.20.40. Therefore, classification to this specific code relies solely on meeting the criteria of being a seamless tube or pipe of other alloy steel, of circular cross-section, not suitable for the aforementioned specialized equipment, and possessing an outside diameter less than 38.1 mm. Any tube failing to meet any of these requirements would be directed to a different HTS classification.