SS 317L contains 3–4% molybdenum — higher than SS 316L — delivering superior pitting and crevice corrosion resistance in aggressive chloride and acid environments. The preferred grade for pulp & paper, flue gas desulphurisation, and chemical processing where 316L is insufficient.
SS 317L is an austenitic stainless steel with higher molybdenum content (3–4%) compared to SS 316L (2–3%). This additional molybdenum significantly improves resistance to pitting and crevice corrosion in aggressive environments containing chlorides, sulphates, and reducing acids. The "L" designation indicates low carbon content (max 0.03%), which prevents sensitization during welding and makes it ideal for fabricated assemblies.
SS 317L is widely used in pulp and paper mills, flue gas desulphurisation (FGD) systems, chemical processing, and food & beverage plants where 316L doesn't provide sufficient corrosion protection. It offers a cost-effective alternative to more expensive nickel alloys in moderately aggressive environments.
| Property | Value |
|---|---|
| Grade | SS 317L |
| ASTM / ASME | ASTM A403 WP317L |
| UNS Number | S31703 |
| Chromium (Cr) | 18–20% |
| Nickel (Ni) | 11–15% |
| Molybdenum (Mo) | 3.0–4.0% |
| Carbon (C) max | 0.03% |
| Max Service Temp | 870°C |
| Fitting Standard | ASME B16.9 / MSS SP-43 |
| Size Range | ½" NB to 48" NB |
| Certificate | EN 10204 3.1 MTC |
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