S317L and S316L are widely used low-carbon austenitic stainless steels, known for their excellent corrosion resistance. The core difference between them lies in their alloy composition, particularly the difference in molybdenum (Mo) content, which directly leads to significant differences in corrosion resistance, mechanical strength, and applicable scenarios. HT PIPE is a SS 316L and SS317L supplier with 15+ export experience. Contact us for more information and quotes for free!
Comparison of Chemical Compositions
|
Element |
Content Range of S317L |
Content Range of S316L |
|
Carbon (C) |
≤0.03 |
≤0.03 |
|
Chromium (Cr) |
18.00-20.00 |
16.00-18.00 |
|
Nickel (Ni) |
11.00-15.00 |
10.00-14.00 |
|
Molybdenum (Mo) |
3.00-4.00 |
2.00-3.00 |
|
Manganese (Mn) |
≤2.00 |
≤2.00 |
|
Silicon (Si) |
≤1.00 |
≤1.00 |
|
Phosphorus (P) |
≤0.045 |
≤0.045 |
|
Sulfur (S) |
≤0.030 |
≤0.030 |
Comparison of Mechanical Properties
|
Performance Indicator |
S317L |
S316L |
|
Tensile Strength (MPa) |
≥485 |
≥485 |
|
Yield Strength (MPa) |
≥170 |
≥170 |
|
Elongation (%) |
≥40 |
≥40 |
|
Brinell Hardness (HB) |
≤207 |
≤217 |
Analysis of Corrosion Resistance
Resistance to Pitting and Crevice Corrosion: This is the most significant performance difference between the two. Pitting and crevice corrosion are common in environments containing chloride ions. The higher molybdenum content of S317L results in a higher Pitting Resistance Equivalent Number (PREN), making its corrosion resistance significantly superior to S316L in chloride solutions (such as seawater and salt spray).
Resistance to Uniform Corrosion: When exposed to media such as sulfuric acid, phosphoric acid, and organic acids, S317L, due to its higher alloy content, has a wider range of corrosion resistance and allows for higher concentrations and temperatures of the media.
Resistance to Stress Corrosion Cracking (SCC): Although both are austenitic stainless steels and are susceptible to stress corrosion cracking in hot chloride environments, S317L, due to its higher alloy content, has relatively better SCC resistance.
When to Choose S316L or S317L?
Scenarios where S316L is the preferred choice
Environments with low to moderate chloride ion concentrations, such as building facades in most areas and non-direct splash zones of coastal buildings.
Industries requiring hygiene and general corrosion resistance, such as food, beverage, and pharmaceutical industries, where the media are typically not highly corrosive.
Cost-sensitive projects with mild operating environments (e.g., ordinary water media, atmospheric environments).
Scenarios where S317L must be considered
High-concentration chloride environments: such as harsh marine atmospheres, components frequently exposed to seawater spray, and certain seawater treatment units.
Chemical and energy industries: equipment, pipelines, and heat exchangers (especially plate heat exchangers) in contact with acidic media such as sulfuric acid and phosphoric acid. Critical parts in flue gas desulfurization (FGD) systems also often use S317L or higher-grade materials.
Pulp and paper industry: equipment and vessels involved in bleaching processes (containing chlorides).
Technical Procurement Assistance from HT PIPE
Selecting the correct grade prevents catastrophic asset failures and optimizes material overhead costs. Zhengzhou Huitong Pipeline Equipment Co., Ltd. (HT PIPE) specializes in processing, pre-fabricating, and exporting complete alloy solutions-including seamless pipes, welded tubes, heavy plates, forged flanges, and precision pipe fittings.
Full material certification (MTC to EN 10204 3.1) available on all shipments.
In-house testing capabilities covering destructive, non-destructive, and chemical analysis.
Custom pipe spool pre-fabrication built exactly to your isometric engineering drafts.
Contact our engineering support team directly at market@htpipe.com to request a detailed technical quotation or material catalog tailored to your specifications.
