Stainless Steel Scrap Guide: 304, 316 and 18-8 for Export Buyers

1. 18-8 and Why It Is Shorthand for 304

'18-8' refers to the nominal composition of 18% chromium and 8% nickel found in AISI 304 stainless steel. Yards and traders often use 18-8 and 304 interchangeably, though strictly speaking 18-8 also covers 302 and 301.

For export contracts we always specify the exact ISRI or AISI grade in writing to avoid disputes when the nickel percentage is checked at the destination smelter.

2. 304 vs 316: The Molybdenum Premium

316 stainless steel contains 2–3% molybdenum, which improves corrosion resistance in chloride environments (marine, pharma, food processing). Molybdenum is an expensive alloying element, and 316 scrap therefore trades at a meaningful premium over 304.

Buyers should never accept a mixed 304/316 lot priced as straight 304. Magnetic and chemical testing at loading is fast, cheap and standard practice.

3. ISRI Grade Names Used in Practice

ISRI uses the following names for stainless export trade: Sabot (304 solids), Ulsin (304 turnings), and various Inox designations for 316 and duplex grades. Most European yards now use the AISI numbering (304, 316, 321, 904L) directly in quotations because it is more precise and matches the destination smelter's purchase contracts.

4. Pricing Logic: Nickel Is the Key Variable

Stainless scrap is priced as the sum of recoverable alloy values minus a processing margin. The dominant input is the LME nickel price, applied to the recoverable nickel content of the lot. Chromium and molybdenum are added at index prices, and the carbon iron base is valued at a small positive number.

A typical 304 turning is quoted at roughly 60–70% of the recoverable nickel value plus alloy credits, CIF Asian port. This is a different mental model from aluminum or copper pricing and trips up first-time buyers.

5. Solids vs Turnings

Solids (sheet, plate, pipe and fabricated cut-offs) are cleaner, drier and trade at a premium. Turnings (machining swarf from CNC operations) often carry cutting oil and require briquetting or centrifuging before remelt; they trade at a discount of roughly 5–10% versus solids of the same alloy.

Oil content above 3% triggers safety concerns at the smelter and is grounds for rejection or downgrade.

6. Container Loading

Stainless solids load densely — a 20GP container reaches 23–25 MT and may even max out the road weight limit before the cargo cap. Turnings, if briquetted, load 22–24 MT; loose turnings load 18–20 MT and are usually shipped in big-bags to prevent spillage.

Containerisation of mixed 304 and 316 lots is technically possible with separated big-bags clearly labelled, but most buyers prefer one-grade-per-container to simplify customs and quality processes.

7. Inspection: Magnetic Test and PMI

Austenitic 304 and 316 are non-magnetic in the annealed condition. A quick magnet sweep at loading identifies any 400-series ferritic stainless mixed in by mistake. For high-value contracts, a Positive Material Identification (PMI) handheld XRF analyser is used to confirm chemistry on a per-pallet basis.

SGS, Bureau Veritas and Intertek all offer PMI as part of their pre-shipment inspection package. The cost is modest and the protection is significant.