Tubo de Acero Inoxidable 304L vs 316L
The most common material selection question in industrial piping. Here is the complete side-by-side comparison.
| Property | 304L | 316L |
|---|---|---|
| UNS Number | S30403 | S31603 |
| EN Number | 1.4307 | 1.4404 |
| Chromium (Cr) | 18.0 – 20.0% | 16.0 – 18.0% |
| Nickel (Ni) | 8.0 – 12.0% | 10.0 – 14.0% |
| Molybdenum (Mo) | — (none) | 2.0 – 3.0% |
| Tensile Strength | ≥ 515 MPa (75 ksi) | ≥ 485 MPa (70 ksi) |
| Yield Strength | ≥ 205 MPa (30 ksi) | ≥ 170 MPa (25 ksi) |
| Elongation | ≥ 40% | ≥ 40% |
| Hardness (max) | 90 HRB | 90 HRB |
| PREN | 18 – 20 | 24 – 28 |
| Max Cl⁻ (ambient) | ~200 ppm | ~1,000 ppm |
| Critical Pitting Temp | < 15°C | 15 – 25°C |
| Density | 8.00 g/cm³ | 8.00 g/cm³ |
| Relative Cost | 1.0× (base) | 1.3 – 1.5× |
Elegir 304L Cuando:
- No chloride exposure (fresh water only)
- General industrial, architectural, food processing
- Low-temperature service (cryogenic to 400°C)
- Budget-sensitive projects where 316L premium is not justified
Elegir 316L Cuando:
- Chloride present (coastal, chemical, desalination)
- Offshore platforms and marine environments
- Acidic process environments (sulfuric, phosphoric)
- Any application where 304L would have < 5 year service life
Conclusion
El sobrecosto del 30-50% para el 316L compra molibdeno — el elemento que transforma el acero inoxidable de 'propósito general' en 'grado marino'. Si su entorno tiene CLORUROS (agua salada, sal de carretera, productos químicos industriales, incluso humedad costera), el 316L es el estándar mínimo. El 304L en servicio con cloruros es una bomba de tiempo hacia la falla por corrosión por picaduras.