Austenitic, duplex, and super duplex stainless steel grades for EN 10253-2 Type B buttweld fittings — from standard 304L/316L to high-alloy duplex and 904L. Delta ferrite reporting, NACE hardness compliance, and Ra surface finish available.
Base austenitic grade. Food, water, cryogenic, architectural. No Mo — pitting in chloride-containing media. Widely available, most cost-effective stainless.
Standard Mo-bearing austenitic. 2.0–2.5% Mo adds pitting resistance. Pharmaceutical, food, marine, chemical. Most widely specified EN stainless for process piping.
Higher Mo than 1.4404 (2.5–3.0% vs 2.0–2.5%). Marginal PRE improvement over 316L. Coastal environments and moderately aggressive chloride service where 316L is borderline.
Ti-stabilised austenitic. Prevents sensitisation at 400–800°C. Heat exchangers, exhaust headers, furnace systems. Filler must be ER347 (Nb-stabilised) — not ER321.
High-alloy austenitic. 4.5% Mo + 1.5% Cu bridges 316L and duplex. H₂SO₄, H₃PO₄, seawater, FGD. Fully austenitic (no sigma risk). Filler ERNiCrMo-3.
Standard duplex — austenitic-ferritic microstructure. 2× yield of 316L. NACE MR0175 compliant. Offshore, sour gas, seawater piping, pulp and paper. Filler ER2209.
Maximum duplex pitting resistance. 25Cr-7Ni-4Mo+N. Deep subsea, desalination, aggressive offshore. Sigma phase risk above 300°C — solution anneal after forming. Filler ER2594.
| Grade | EN Number | UNS | Mo% | PRE (typical) | Key Application |
|---|---|---|---|---|---|
| 304 / 304L | 1.4301 | S30400 | — | ~18 | General, food, water |
| 316L | 1.4404 | S31603 | 2.0–2.5 | ~24 | Process, pharma, marine |
| 316Mo | 1.4436 | S31600 | 2.5–3.0 | ~26 | Coastal, moderate chloride |
| 904L | 1.4539 | N08904 | 4.0–5.0 | ~35 | H₂SO₄, seawater, FGD |
| Duplex 2205 | 1.4462 | S31803 | 2.5–3.5 | ≥35 | Sour gas, offshore |
| Super Duplex 2507 | 1.4410 | S32750 | 3.0–5.0 | ≥40 | Deep subsea, desalination |
Delta ferrite number (FN) reports are available for 1.4404 and 1.4301 grades — mandatory for pharmaceutical WFI piping per ISPE / EU Annex 1 requirements. NACE MR0175 hardness compliance with HRC/HBW certificate is available for duplex and super duplex grades in sour service. See full quality and certification options.
EN 10253-2 Type B. EN 10204 3.1. NACE MR0175. PED 2014/68/EU. Delta ferrite, PMI, Ra report available. Contact us with grade, size schedule, certifications, and delivery location.
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