What is the purpose of A335 pipe
Jul 10, 2025
Overview of core functions
A335 steel pipe is specially designed for high temperature and high pressure conditions, providing heat resistance, creep resistance and corrosion resistance. It is mainly used in high temperature fluid transportation systems (such as steam, oil and gas media) in the fields of energy, petrochemicals, etc. The maximum service temperature can reach 650℃ and the pressure resistance ≥9.8MPa.
Key application areas
1. Energy and power system
Key components of boilers: superheater, reheater pipes (wall temperature ≤650℃) and main steam pipes, suitable for supercritical units.
Nuclear power equipment: heat transfer tubes of nuclear island secondary circuit heat exchangers (550℃/20MPa environment).
2. Petrochemical equipment
Cracking furnace tubes: withstand 650℃ high temperature cracking reaction and resist hydrogen sulfide corrosion.
Hydrogenation reactor pipes: resist damage from high pressure hydrogen environment (such as desulfurization and cracking processes).
3. High-temperature fluid transportation
High-pressure steam pipeline: steam transportation in power plants and chemical plants (pressure > 9.8 MPa).
Oil and gas gathering and transportation pipeline: corrosion-resistant transportation pipeline in acidic environment
Material grade and performance differences
| Grade | Composition | Applicable temperature | Applications |
|---|---|---|---|
| P5 | 5Cr-0.5Mo | ≤550℃ | Medium temperature boiler superheater, petrochemical heat exchanger |
| P9 | 9Cr-1Mo | ≤650℃ | High-pressure boiler reheater, cracking furnace tube |
| P11 | 1.25Cr-0.5Mo | ≤540℃ | Boiler economizer, medium pressure steam pipeline |
| P22 | 2.25Cr-1Mo | ≤580℃ | Power plant main steam pipeline, hydrogenation reactor |
| P91/P92 | 9Cr-1Mo-VNb / 9Cr-1.8W | ≤650℃ | Main steam pipeline of supercritical unit |
Core performance advantages
High temperature stability:
Chromium (Cr) forms a dense oxide film (such as P91 contains 9% Cr), and the anti-oxidation temperature reaches 650℃.
Molybdenum (Mo) and tungsten (W) enhance creep resistance (P92 allowable stress ≥110MPa at 580℃).
Mechanical properties:
Tensile strength: ≥415-585 MPa (P91 reaches 585MPa).
Sustainable plasticity: Fracture time ≥100 hours under 650℃/100MPa.
Process adaptability:
Supports welding and cold bending processing (P91 needs to be preheated at 200-300℃).
Material selection and manufacturing points
Heat treatment process: forced normalizing + tempering (such as P91: 1040℃ normalizing + 760℃ tempering), optimize tempered martensite structure.
Quality Inspection:
Hydraulic test (pressure ≥ 20MPa) to verify the sealing;
Ultrasonic testing to detect internal defects (cracks ≤ 0.2mm).
