Several 10-digit lines within 730640 are differentiated by nickel content — specifically whether the steel contains over 0.5% nickel and whether it falls below or above 24% nickel. These thresholds correspond broadly to austenitic grades (higher nickel, e.g., 304/316) versus ferritic or martensitic grades (lower nickel). The mill test report's certified chemical composition is the authoritative document for determining the correct line, and misclassification between nickel-content brackets is a common audit finding.

India is the leading supplier of welded stainless steel tubes to the US under this heading. Importers should check whether any antidumping or countervailing duty orders on welded stainless steel pipe or tube from India are active and whether the specific product — by grade, wall thickness, and outside diameter — falls within the scope of such orders. Section 232 tariffs on steel apply broadly, but AD/CVD exposure is product- and order-specific and should be verified before entry.