7305.20.20.00 - Threaded or coupled

This category, HTS 7305.20.20.00, specifically covers tubes and pipes of iron or nonalloy steel with circular cross-sections, exceeding 406.4 mm in external diameter, that are designed for use as casing in drilling operations for oil or gas. The defining characteristic for this subcategory is that these pipes are manufactured with threaded or coupled ends, enabling them to be securely joined together to form the casing string required for deep well exploration and extraction.

Distinguishing this category from its sibling, 7305.20.40.00 ("Other"), is the explicit inclusion of pipes with threaded or coupled connections. While the sibling category encompasses other tubes and pipes meeting the diameter and material criteria but lacking these specific joining features, this classification is precisely for those engineered for robust connection and sealing purposes within the demanding environment of oil and gas drilling. This focus on the method of joining is the key differentiator.

As this is a leaf node in the HTS structure, there are no further subcategories. Therefore, classification under 7305.20.20.00 hinges directly on the presence of threaded or coupled ends and the intended application as oil or gas well casing, alongside the established diameter and material requirements of the parent categories. Examples of goods falling here would include API-grade casing pipes with pre-machined threads for connection.