7306.61 - Of square or rectangular cross section:

This HTS category, 7306.61, specifically covers welded tubes, pipes, and hollow profiles made of iron or steel that are of a non-circular cross-section, with a particular emphasis on those having a square or rectangular shape. This designation differentiates them from other non-circular profiles which are categorized under sibling headings. The key defining characteristic for inclusion here is the explicitly square or rectangular form of the profile's cross-section.

When classifying articles within this group, it is crucial to distinguish them from other non-circular cross-section profiles (HTS 7306.69). While both fall under the broader category of welded tubes, pipes, and hollow profiles of non-circular cross-section, 7306.61 is exclusively for those that exhibit a perfectly square or rectangular geometry. Other shapes, such as oval, hexagonal, or any other non-circular, non-rectangular form, would be classified under the sibling category.

The subcategories within 7306.61 further refine the classification based on a critical physical attribute: wall thickness. Articles with a wall thickness of 4 mm or more form one distinct group, while those with a wall thickness less than 4 mm constitute another. This distinction is important for customs valuation and statistical purposes, reflecting potential differences in manufacturing processes, material usage, and intended applications of these square or rectangular hollow profiles.