347H stainless steel pipe is a high-performance alloy known for its excellent corrosion resistance and high-temperature strength, making it a go-to choice in demanding industrial environments. Its unique composition, particularly the addition of niobium, sets it apart, ensuring stability even under extreme conditions.
347H Stainless Steel Pipe: Key Characteristics
347H is an austenitic stainless steel, part of the 300 series, with a chemical composition that includes chromium (17-19%), nickel (9-13%), and niobium (columbium, 5x the carbon content minimum) as key alloying elements. This combination grants it superior resistance to intergranular corrosion, especially after exposure to high temperatures, which is critical in applications like boilers and heat exchangers. The "H" designation indicates a higher carbon content (0.04-0.10%), enhancing its strength at elevated temperatures compared to standard 347.
Typical Applications
Thanks to its ability to withstand temperatures up to 1500°F (816°C) and resist oxidation and carbide precipitation, 347H pipe is widely used in:
- Power generation (boiler tubes, superheaters)
- Chemical processing (reactors, pipelines handling corrosive fluids)
- Petrochemical industry (refinery equipment)
- High-temperature exhaust systems
Mechanical Properties
| Property | Value |
| Tensile Strength | 75,000 psi (min) |
| Yield Strength | 30,000 psi (min) |
| Elongation | 40% (min in 2") |
| Hardness | 95 HRB (max) |
Advantages Over Similar Alloys
Compared to 304 or 316 stainless steel, 347H offers better high-temperature stability and reduced risk of sensitization (carbide formation at grain boundaries), which is crucial for welded components in corrosive environments. It outperforms 321 in higher temperature ranges, making it a preferred choice for extreme heat applications.
