304L vs 316L Stainless Steel Pipe
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× |
Choose 304L When:
- 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
Choose 316L When:
- 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
The Bottom Line
The 30-50% cost premium for 316L buys you molybdenum — the element that transforms general-purpose stainless into marine-grade stainless. If your environment has ANY chlorides (saltwater, road salt, industrial chemicals, even coastal humidity), 316L is the minimum standard. 304L in chloride service is a ticking clock to pitting corrosion failure.