The HS schedule explicitly separates stainless steel scrap (7204.21) from other alloy steel scrap (7204.29) because stainless steel — defined by a minimum chromium content of 10.5% — has distinct metallurgical value and recycling pathways. Mixing grades at classification can affect duty liability and, more practically, the remelting specifications accepted by the receiving mill.

Portable XRF (X-ray fluorescence) analyzers are widely used at the point of collection and at port to verify alloy grade. Suppliers typically provide a grade declaration or spectrographic certificate. For mixed or uncertain grades, conservative classification and a request for CBP binding ruling may be appropriate to avoid post-entry reclassification.