SS 316L stainless steel belongs to the category of iron alloys, while Nickel 825 belongs to the category of nickel alloys.
Here's a comparison between the two:
1. Chemical Composition:
SS316L (316L Stainless Steel Pipe): SS316L is a low-carbon variant of stainless steel 316. It primarily consists of iron, chromium (16-18%), nickel (10-14%), molybdenum (2-3%), and a small amount of carbon (<0.03%). It is known for its excellent corrosion resistance, especially in various environments.
Alloy 825 Pipe, also known as Incoloy 825 UNS N08825, is a nickel-iron-chromium alloy. It contains a significant amount of nickel (38-46%), chromium (19.5-23.5%), iron (22-26%), and smaller amounts of molybdenum (2.5-3.5%), copper (1.5-3%), and titanium (0.6-1.2%). This alloy is highly corrosion-resistant and particularly suited for aggressive environments.
| Element | SS316L (UNS S31603) | Alloy 825 (UNS N08825) |
| Nickel (Ni) | 10.0 – 14.0% | 38.0 – 46.0% (High Nickel Base) |
| Chromium (Cr) | 16.0 – 18.0% | 19.5 – 23.5% |
| Iron (Fe) | Balance (~65–70%) | 22.0% min (Balance) |
| Molybdenum (Mo) | 2.0 – 3.0% | 2.5 – 3.5% |
| Copper (Cu) | - | 1.5 – 3.0% |
| Titanium (Ti) | - | 0.6 – 1.2% (Stabilizing Element) |
| Carbon (C) | 0.030% max | 0.05% max |
2. Corrosion Resistance:
- SUS 316L: UNS S31603 offers excellent corrosion resistance, making it suitable for a wide range of applications, including marine environments and chemical processing.
- Incoloy 825: Incoloy Alloy 825 is renowned for its exceptional resistance to various corrosive media, including sulfuric acid, phosphoric acid, and chloride-containing solutions. It is often used in severely corrosive environments, such as chemical processing and oil and gas industry applications.
3. Temperature Resistance:
- AISI 316L: DIN 1.4404 has good high-temperature properties and can operate at temperatures up to about 870°C (1600°F). It maintains its corrosion resistance at elevated temperatures.
- Alloy 825: 2.4858 Alloy 825 is designed for high-temperature applications and can withstand temperatures up to about 540°C (1000°F) while maintaining its corrosion resistance.
4. Applications:
- Alloy 316L: SS 316L stainless steel is commonly used in industries like food processing, pharmaceuticals, and general-purpose applications where corrosion resistance and durability are required.
- Inconel 825: Nickel alloy 825 finds applications in aggressive environments where strong corrosion resistance is crucial, such as chemical processing, oil and gas production, and marine environments.
5. Cost:
- SS316L: Stainless steel, including SS316L, is generally more cost-effective than nickel-based alloys like Incoloy 825.
6. Magnetic Properties:
- SS 316L: SS316L is typically non-magnetic or exhibits very weak magnetic properties.
- Nickel 825: Alloy 825 is generally non-magnetic.
7. Mechanical & Physical Property Comparison
| Property | SS316L (Annealed) | Alloy 825 (Grade 1 / Annealed) |
| Tensile Strength, min. | 70 ksi (485 MPa) | 85 ksi (586 MPa) |
| Yield Strength (0.2% Offset), min. | 25 ksi (170 MPa) | 35 ksi (240 MPa) |
| Elongation in 2 in. (50mm) | 40% | 30% |
| Applicable ASTM Specifications | ASTM A312, ASTM A240 | ASTM B424, ASTM B407, ASTM B705 |
| Density | 8.0 g/cm³ | 8.14 g/cm³ |
When to Select SS316L:
Food, beverage, and pharmaceutical processing equipment.
Architectural, structural, and general piping under 60℃.
Moderate chemical environments with low chloride exposure.
When to Upgrade to Alloy 825:
Sulfuric & Phosphoric Acid piping, tanks, and heat exchangers.
Downhole oil and gas equipment.
Marine heat exchangers handling hot seawater or brackish cooling water.
Nuclear fuel reprocessing and acid pickling tanks.
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