Deutsche Version: Formstücke aus 1.4404 (316L)
X2CrNiMo17-12-2 · ASTM A403 WP316L · S31603 · PRE ~24
The most widely specified stainless steel for chemical process, pharmaceutical, food & beverage, and general industrial piping worldwide. Low carbon (C ≤ 0.030%) prevents intergranular sensitisation in the weld HAZ. 2–2.5% Mo provides chloride resistance beyond 304L. The default SS grade for UK, Netherlands, Scandinavia, and USA projects.
| System | Designation |
|---|---|
| EN Werkstoffnummer (W.Nr.) | 1.4404 |
| EN Grade Name | X2CrNiMo17-12-2 |
| ASTM UNS | S31603 |
| ASTM Fittings | A403 WP316L (dual-cert: 316/316L) |
| AWS Filler (GTAW) | ER316L |
| AWS Filler (SMAW) | E316L-15 / E316L-17 |
| European Market Use | UK, NL, Scandinavia, USA — dominant 316L specification |
| CE Europe / Germany | Specify 1.4571 (316Ti) instead — different convention |
| Element | 1.4404 (316L) | 1.4401 (316) | Role |
|---|---|---|---|
| C | ≤0.030% | ≤0.070% | Low C prevents Cr₂₃C₆ precipitation (sensitisation) |
| Cr | 16.5–18.5% | 16.5–18.5% | Passive film, pitting resistance |
| Ni | 10.0–13.0% | 10.0–13.0% | Austenite stability, corrosion resistance |
| Mo | 2.0–2.5% | 2.0–2.5% | PRE contribution: 3.3×%Mo — chloride pitting resistance |
| N | ≤0.10% | ≤0.10% | PRE contribution: 16×%N — strengthening |
| PRE (calculated) | ~24 | ~24 | Cr + 3.3Mo + 16N |
| W.Nr. | Grade | PRE | Key Feature | Specify When |
|---|---|---|---|---|
| 1.4401 | 316 | ~24 | Standard 316 | Non-welded service only; prefer 316L |
| 1.4404 ★ | 316L | ~24 | Low C (≤0.030%) | UK/NL/USA — standard welded SS piping |
| 1.4571 ★ | 316Ti | ~24 | Ti stabilised | Germany/Italy/CE Europe — DIN/AD 2000 convention |
| 1.4432 | 316L Hi-Mo | ~26 | Mo 2.5–3.0% | Moderate chloride uplift; specify explicitly |
| 1.4435 | 316L High-Ni | ~26 | Ni 12.5–15%; FN≤1 | Nuclear, pharma WFI, fatigue-critical |
DN15–DN600 and larger. Outside diameters follow the EN 10220 / EN ISO 1127 pipe series; wall thickness is matched to your connecting pipe.
| Size | OD (mm) |
|---|---|
| DN 15 | 21.3 |
| DN 20 | 26.9 |
| DN 25 | 33.7 |
| DN 32 | 42.4 |
| DN 40 | 48.3 |
| DN 50 | 60.3 |
| DN 65 | 76.1 |
| DN 80 | 88.9 |
| DN 100 | 114.3 |
| DN 125 | 139.7 |
| DN 150 | 168.3 |
| DN 200 | 219.1 |
| DN 250 | 273.0 |
| DN 300 | 323.9 |
| DN 350 | 355.6 |
| DN 400 | 406.4 |
| DN 450 | 457.0 |
| DN 500 | 508.0 |
| DN 600 | 610.0 |
EN 1.4404 is the European Werkstoffnummer for X2CrNiMo17-12-2, equivalent to ASTM S31603 / A403 WP316L. The 'L' in 316L designates the low-carbon variant (C ≤ 0.030% EN, ≤ 0.035% ASTM) that prevents chromium carbide precipitation (sensitisation) at grain boundaries during welding — making it safe for welded fabrication without risk of intergranular corrosion in the heat-affected zone.
Both 316L (1.4404) and 316Ti (1.4571) solve the sensitisation problem of standard 316 — 1.4404 via low carbon, 1.4571 via titanium stabilisation. 1.4404 is the dominant specification in UK, Netherlands, Scandinavia and USA (and dual-certified as 316/316L). 1.4571 dominates in Germany, Austria, Italy, Czech Republic and Poland — largely following DIN specifications and AD 2000 pressure vessel codes. For a European project, check the engineering company's home country convention. Technically, both are suitable for standard process piping to ~425°C. For service above 425°C, 1.4571's TiC stabilisation gives an advantage.
Both are 316L-equivalent grades, but 1.4432 has higher molybdenum: Mo 2.5–3.0% vs Mo 2.0–2.5% for 1.4404. This gives 1.4432 a slightly higher PRE (~26 vs ~24) and better pitting resistance in chloride environments. However, ASTM A403 WP316L covers both the 1.4404 and 1.4432 Mo ranges — so a WP316L certificate alone doesn't distinguish them. For European projects requiring the higher Mo, specify 1.4432 explicitly by W.Nr.
Supplying an Indian boiler or ASME B16.9 project? The equivalent grade is listed on our group site ibrfittings.com: ASTM A403 WP316L fittings.
