ASTM A335 / ASME SA335 P9 / UNS S50400 Cr-Mo Alloy Steel Seamless Pipe
ASTM A335 / ASME SA335 Grade P9 / UNS S50400 Alloy Steel Seamless Pipe Black Painted
ASTM A335 P9 is a seamless, chromium-molybdenum alloy steel pipe designed for high-temperature and high-pressure applications. With 8–10% chromium and 0.9–1.1% molybdenum, it offers exceptional resistance to oxidation, creep, and thermal stress at temperatures up to 650°C (1,200°F). It is widely used in critical environments like power plant steam lines, oil refineries, petrochemical processing, and boiler systems where long-term reliability under extreme conditions is essential. P9 requires specialized welding/preheat treatment but outperforms lower-grade alloys in demanding industrial settings.
Equivalent Material of ASTM A335/ASME SA335 Alloy Steel Seamless Pipe
| UNS | ASTM | EN | DIN | JIS | GB |
| K50400 | P9 | 12Cr9Mo | X12CrMo91 | STBA26 | / |
Chemical composition(%) of ASTM A335/ASME SA335 Alloy Steel Seamless Pipe
| Grade | C | Mn | P≤ | S≤ | Si≤ | Cr | Mo |
| P11 | .05-0.15 | 0.30-0.60 | 0.025 | 0.025 | .50-1.00 | 1.00-1.50 | .44-0.65 |
| P22 | .05-0.16 | 0.30-0.60 | 0.025 | 0.025 | ≤0.50 | 1.90-2.60 | .87-1.13 |
| P5 | ≤0.15 | 0.30-0.60 | 0.025 | 0.025 | ≤0.50 | 4.00-6.00 | .45-0.65 |
| P9 | ≤0.15 | 0.30-0.60 | 0.025 | 0.025 | .25-1.00 | 8.00-10.00 | .90-1.10 |
| P91 | 0.08-0.12 | 0.30-0.60 | 0.020/0.010 | 0.020/0.010 | .02-0.50 | 8.00-9.50 | .85-1.05 |
| P92 | 0.07-0.13 | 0.30-0.60 | 0.020/0.010 | 0.020/0.010 | ≤0.50 | 8.50-9.50 | .30-0.60 |
Advantages:
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Superior creep strength under sustained high temps.
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Oxidation/sulfidation resistance (due to Cr content).
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Good weldability (requires pre/post-weld heat treatment).
Mechanical Property of ASTM A335/ASME SA335 Alloy Steel Seamless Pipe
| Steel Grade | Tensile Strength, Mpa | Yield Strength, Mpa | Elongation, % |
| P5 | Min: 415 | Min: 205 | Min: 30 |
| P9 | Min: 415 | Min: 205 | Min: 30 |
| P11 | Min: 415 | Min: 205 | Min: 30 |
| P12 | Min: 415 | Min: 205 | Min: 30 |
| P22 | Min: 415 | Min: 205 | Min: 30 |
| P91 | Min: 415 | Min: 415 | Min: 20 |
Application
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Power Plants: Superheaters, reheaters, high-temp steam lines.
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Oil & Gas: Refinery piping, catalytic cracker units, hydrogen service.
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Petrochemical: High-pressure/temperature process pipelines.
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Boilers: Critical pressure parts in fossil-fuel boilers.
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