Phosphorus above 0.5% lowers the melting point and improves the fluidity of molten iron, making this grade useful for thin-section gray iron castings such as decorative ironwork, cookware, and certain automotive components where fine detail is required. For structural or ductile iron applications, low-phosphorus grades are generally preferred.

Heading 7201.10 covers pig iron containing 0.5% or less phosphorus, so a reading of exactly 0.5% falls under 7201.10. Only content strictly greater than 0.5% triggers classification under 7201.20. When analytical results are borderline, obtaining a second independent test and retaining documentation is advisable to support the declared classification.