ASME SA789 S31803 Duplex Stainless Steel Heat Exchanger Tube
ASME SA789 S31803 Duplex Stainless Steel Heat Exchanger Tube
Grade S31803 is a duplex stainless steel, it has a mixed microstructure of austenite and ferrite phases, typically in a 50/50 ratio. This combination provides enhanced strength and resistance to stress corrosion cracking compared to standard austenitic stainless steels. S31803 is known for its excellent performance in highly corrosive environments, particularly those containing chlorides and other aggressive chemicals.
Chemical Composition:
| Grade | C | Mn | Si | P | S | Cr | Ni | Mo | N | Fe |
| S31803 | ≤ 0.03% | ≤ 2.00% | ≤ 1.00% | ≤ 0.03% | ≤ 0.02% | 21.00-23.00% | 4.50-6.50% | 2.50-3.50% | 0.08-0.20% | Balance |
Mechanical Properties:
| Grade | Tensile Strength | Yield Strength | Elongation | Hardness |
| S31803 |
Minimum 620 MPa (90,000 psi) |
Minimum 450 MPa (65,000 psi) |
25% minimum in 50 mm |
≤ 290 HB (Brinell Hardness) |
Key Features:
- High Strength: Approximately twice the yield strength of austenitic stainless steels.
- Corrosion Resistance: Excellent resistance to pitting, crevice corrosion, and stress corrosion cracking, especially in chloride environments.
- Weldability: Good weldability with proper technique and post-weld treatment.
- Durability: High mechanical strength and toughness, even at low temperatures.
Applications:
1. Chemical Processing Industry
- Heat Exchangers: Used in heat exchangers where aggressive chemicals are processed, ensuring high performance and longevity.
- Reactors and Pressure Vessels: Suitable for reactors and pressure vessels dealing with highly corrosive substances.
- Piping Systems: Ideal for piping systems that transport aggressive chemicals at high pressures and temperatures.
2. Oil and Gas Industry
- Offshore Platforms: Suitable for offshore oil rigs and platforms where exposure to seawater and corrosive environments is common.
- Subsea Equipment: Used in subsea equipment due to its excellent resistance to stress corrosion cracking and pitting.
- Refinery Equipment: Ideal for components in refineries that process sour gas and other corrosive substances.
3. Marine Applications
- Shipbuilding: Used in marine environments where components are exposed to seawater and must resist corrosion.
- Seawater Cooling Systems: Suitable for seawater cooling systems due to its high resistance to chloride-induced corrosion.
- Desalination Plants: Ideal for desalination plant tubing where high resistance to pitting and crevice corrosion is necessary.
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