What is the difference between P22 and P91 pipe
Jan 06, 2026
- From a chemical composition perspective, P91 steel pipes mainly contain chromium, molybdenum, and vanadium, with chromium content around 9%, molybdenum around 1%, and vanadium around 0.25%. These components give it good high-temperature performance and oxidation resistance. In contrast, P22 steel pipes have a relatively lower chromium content, approximately 2.25%-2.5%, and a molybdenum content of approximately 0.5%-0.6%, resulting in inferior high-temperature performance and oxidation resistance compared to P91 steel pipes.
- Regarding performance, P91 seamless steel pipes exhibit excellent high-temperature strength and creep resistance, enabling long-term stable operation in environments above 600°C. They also have a relatively low coefficient of thermal expansion and good dimensional stability at high temperatures. P22 seamless steel pipes, on the other hand, are primarily suitable for medium-temperature applications below 580°C, with relatively weaker high-temperature performance.
- In terms of manufacturing processes, both are basically similar. However, due to differences in material performance requirements, the manufacturing process of P91 steel pipes is more strictly controlled, with higher requirements for raw material quality and heat treatment processes to ensure its performance meets the needs of high-temperature operating conditions.
- In terms of application areas, P91 seamless steel pipes are commonly used in critical components such as high-temperature and high-pressure steam pipelines, superheaters, and reheaters, ensuring the safe operation of equipment under high-temperature conditions. P22 seamless steel pipes are often used in some piping systems in medium-temperature thermal power generation and other fields, but their use under high-temperature conditions is somewhat limited.
Chemical Composition Comparison Table for A335 P22 and P91
| Component | P22 (ASTM A335) | P91 (ASTM A335) |
|---|---|---|
| C | 0.15-0.25 | 0.08-0.12 |
| Mn | 0.30-0.60 | 0.30-0.60 |
| P | ≤0.025 | ≤0.025 |
| S | ≤0.015 | ≤0.015 |
| Si | ≤0.50 | ≤0.50 |
| Cr | 1.90-2.60 | 8.50-9.50 |
| Mo | 0.87-1.13 | 0.30-0.60 |
| V | - | 0.15-0.25 |
| Ni | ≤0.40 | ≤0.40 |
Mechanical Properties Comparison Table for A335 P22 and P91
| Performance Indicator | P22 (ASTM A335) | P91 (ASTM A335) |
|---|---|---|
| Yield Strength (MPa) | ≥205 | ≥415 |
| Tensile Strength (MPa) | ≥415 | ≥585 |
| Elongation (%) | ≥25 | ≥20 |
| Hardness (HB) | ≤187 | ≤241 |
Mechanical Properties Comparison Table for A335 P22 and P91
| Performance Indicator | P22 (ASTM A335) | P91 (ASTM A335) |
|---|---|---|
| Elastic Modulus (GPa) | 200 | 200 |
| Poisson's Ratio | 0.29 | 0.29 |
| Coefficient of Linear Expansion (10⁻⁶/℃) | 12.5 | 12.5 |
| Thermal Conductivity (W/m·K) | 25 | 25 |
A335 P22 P91 Alloy steel pipe for boiler in stock
