ASTM A335 / ASME SA335 P9 Alloy Steel Seamless Pipe For Petrochemical Industry
ASTM A335 P9 alloy steel pipe is a standard specification for seamless ferritic alloy-steel pipe intended for high-temperature service. The "P9" designation refers specifically to a grade of steel that contains approximately 9% Chromium (Cr) and 1% Molybdenum (Mo). The primary characteristic of P9 is its excellent resistance to oxidation, sulfidation, and corrosion at elevated temperatures, combined with good creep-rupture strength. It is specifically designed to withstand prolonged exposure to high temperatures (typically up to 600℃-650℃) without significant loss of mechanical properties.
Manufactured via hot rolling or cold drawing seamless forming processes, the pipe eliminates welding seams, ensuring uniform structural integrity, stable mechanical performance and excellent pressure-bearing capacity. The 9% chromium content endows the material with outstanding high-temperature oxidation resistance and sulfidation corrosion resistance, while molybdenum significantly improves high-temperature creep strength and structural stability under long-term thermal load. Different from high-creep-strength P91/P92 grades, P9 is more targeted at high-temperature corrosion-resistant process piping rather than ultra-supercritical steam pipeline systems, and is a classic and mature chrome-moly alloy pipe for refinery and thermal power industries. This P9 grade pipe is fully compliant with international industrial standards, support bending, flanging and fusion welding, and is suitable for harsh working environments with long-term high temperature, high pressure and corrosive medium erosion.
Chemical Composition:
| Element |
Content Range (wt%) |
| Carbon (C) |
≤0.15 |
| Manganese (Mn) |
0.30 ~ 0.60 |
| Silicon (Si) |
0.25 ~ 1.00 |
| Chromium (Cr) |
8.00 ~ 10.00 |
| Molybdenum (Mo) |
0.90 ~ 1.10 |
| Phosphorus (P) |
≤0.025 |
| Sulfur (S) |
≤0.025 |
Mechanical Properties:
| Tensile Strength |
≥ 415MPa (60000psi) |
| Yield Strength (0.2% Offset) |
≥ 205MPa (30000psi) |
| Elongation (50mm/2in gauge length) |
≥ 30% |
| Maximum Brinell Hardness (HB) |
≤ 250HBW |
Surface Finish Types:
- As Rolled (Black Surface): Original hot-rolled surface, low cost, suitable for internal industrial pipeline projects
- Pickled & Bright Surface: Remove oxide scale, uniform bright surface, convenient for inspection and welding
- Anti-rust Oil Coating: Oiled on inner and outer walls to prevent rust during sea transportation and long-term storage
- Painted Finish: Black varnish, grey anti-high-temperature paint, customized color coating
- Sand Blasting / Shot Blasting: Remove surface burrs and oxide layers, improve coating adhesion
Key Features & Advantages:
Excellent High-Temperature Performance
Superior Corrosion Resistance
Good Creep Resistance
Excellent Process Performance
Stable Mechanical Properties
Cost-Effective
Main Industrial Applications:
Petroleum Industry
Petrochemical Industry
Thermal Power Generation
Chemical Industry
Industrial Heat Exchange Equipment
Power Generation and Energy
Oil and Gas Plant
Industrial Furnaces
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