Products Features
Excellent high-temperature strength and creep resistance (core advantage)
The core advantage of ASTM A335 P22 lies in its excellent high-temperature strength and creep resistance. Thanks to the addition of 1% molybdenum (Mo) (approximately twice the content of P11), P22 exhibits significantly superior high-temperature creep rupture strength compared to P11 and ordinary carbon steel within the temperature range of 500-580°C. Under conditions at 565°C, the allowable stress of P22 is about 1.2-1.4 times that of P11, enabling it to effectively resist slow plastic deformation (creep) of materials under high temperature and pressure, ensuring the safety and reliability of pipelines during long-term high-temperature service. Its minimum tensile strength is 415 MPa and minimum yield strength is 205 MPa, which are standard performance levels within the A335 series. However, it has a significant advantage in terms of high-temperature strength and creep resistance.
Good antioxidant properties and corrosion resistance
The 2.25% chromium content in ASTM A335 P22 provides superior high-temperature oxidation resistance compared to P11. In high-temperature steam environments and sulfur-containing media, P22 can form a more stable Cr₂O₃ oxide layer, effectively resisting high-temperature oxidation and thermal corrosion with an upper temperature limit for oxidation resistance of 565-580°C, which is better than P11 (≤550°C). In refinery high-temperature sulfur-containing media and hydrotreating unit environments, P22 exhibits significantly better corrosion resistance than P11, effectively withstanding high-temperature sulfidation corrosion and hydrogen corrosion.
Good machinability and formability
ASTM A335 P22 exhibits good cold and hot working properties, allowing for various forming processes such as hot bending, cold bending, and forging. Its moderate alloy content provides excellent formability during cold bending, making it suitable for manufacturing pipe fittings like elbows, tees, and reducers. It should be noted that due to its higher chromium and molybdenum content, P22 has a slightly higher tendency for work hardening compared to P11. Therefore, it is recommended to include appropriate intermediate annealing steps during forming processes. Its machinability is comparable to that of P11, and conventional machining methods can be used for processing.
Good welding performance and strict post-weld heat treatment requirements
ASTM A335 P22 has good welding performance. However, due to its higher chromium and molybdenum content (2.25% Cr-1% Mo), its tendency to harden in the heat-affected zone (HAZ) is greater than that of P11, resulting in stricter requirements for welding processes and post-weld heat treatment (PWHT). It is recommended that preheating temperature before welding be 200-300°C. After welding, PWHT must be performed by heating to 690-760°C, holding at temperature, and then cooling slowly to eliminate residual welding stresses, soften the heat-affected zone, and ensure the toughness and crack resistance of the welded joint.
Good organizational stability and long-term service reliability
ASTM A335 P22 exhibits good organizational stability when in long-term service at temperatures ≤580℃. Its 2.25%Cr-1%Mo composition design effectively enhances the material's high-temperature creep strength and oxidation resistance, while inhibiting the spheroidization of pearlite and the growth and agglomeration of carbides, ensuring a low rate of mechanical property degradation during long-term high-temperature service. After normalizing and tempering (N+T) heat treatment, P22 obtains a uniform and fine ferrite + pearlite microstructure, guaranteeing organizational stability and reliability under high-temperature service conditions.
Technical Specifications
Chemical Composition(ASTM A335 / ASME SA335)
|
Element |
Standard requirements |
Note |
|
C |
0.05 - 0.15% |
Low-carbon design ensures weldability and toughness |
|
Mn |
0.30 - 0.60% |
Solid solution strengthening, improve strength |
|
P |
≤ 0.025% |
Harmful elements, strictly controlled |
|
S |
≤ 0.025% |
Harmful elements, strictly controlled |
|
Si |
≤ 0.50% |
Deoxidizer, improve high-temperature oxidation resistance |
|
Cr |
2.00 - 2.50% |
Core elements that provide excellent high-temperature oxidation resistance and corrosion resistance |
|
Mo |
0.87 - 1.13% |
Core elements to enhance high-temperature creep fracture strength (with a content approximately twice that of P11) |
|
Fe |
Remaining quantity(≈ 96%) |
Matrix element |
Physical Properties
|
Performance |
Numerical Value/Range |
Test conditions |
|
Density |
≈ 7.85 g/cm³ |
Room Temperature (20°C) |
|
Melting Point |
≈ 1380-1430°C |
- |
|
Electrical resistance |
≈ 0.34 μΩ·m |
Room Temperature |
|
Thermal Conductivity |
≈ 38 W/(m·K) |
Room Temperature |
|
Coefficient of Thermal Expansion (20-100°C) |
≈ 11.6 × 10⁻⁶ /K |
- |
|
Elastic modulus (Young's modulus) |
≈ 200 GPa |
Room Temperature |
|
Poisson's ratio |
≈ 0.28 |
Room Temperature |
|
Magnetism |
Ferromagnetic |
Ferrite structure, which is magnetic |
Mechanical Properties (Normalized + Tempered, Typical Values, ASTM A335)
|
Performance |
Typical value |
Implementation standards |
|
Tensile Strength |
≥ 415 MPa |
ASTM A335 |
|
Yield Strength (0.2% Offset) |
≥ 205 MPa |
ASTM A335 |
|
Elongation (gauge length 2in/50mm) |
≥ 30% |
ASTM A335 |
|
Hardness |
≤ 217 HB (typical value) |
- |
Note: The strength level of P22 is the same as that of P11 (≥415 MPa). However, its core advantage lies in the excellent high-temperature strength and oxidation resistance provided by 2.25%Cr-1%Mo, rather than an increase in strength. For higher temperature grades (>580°C), it is recommended to use P91.
High-temperature performance
ASTM A335 P22 maintains good strength levels at high temperatures and is suitable for long-term high-temperature service conditions up to 565°C:
|
Temperature |
Tensile strength (MPa, approximately) |
Performance retention rate |
|
Room temperature (20°C) |
≥ 415 |
100% |
|
400°C |
≈ 390 |
≥ 94% |
|
500°C |
≈ 360 |
≥ 87% |
|
550°C |
≈ 310 |
≥ 75% |
Long-term Thermal Stability and Microstructural Stability:
ASTM A335 P22 exhibits good microstructural stability during long-term service at temperatures ≤565°C. The addition of 2.25% Cr-1% Mo effectively enhances high-temperature strength and oxidation resistance. However, microstructural stability decreases and creep strength significantly drops when used long-term above 580°C; thus, it is not recommended for long-term service above 580°C. For higher temperature grades, P91 is recommended.
Heat treatment system
The final performance of ASTM A335 P22 is highly dependent on the heat treatment regime, with common specifications as follows:
1. Normalizing Treatment (Normalizing)
Heat to 900-960°C, hold for a sufficient time (approximately 1 hour per inch of wall thickness), then air cool. This results in a uniform and fine ferrite + pearlite microstructure, preparing for subsequent tempering.
2. Tempering treatment(Tempering)
Heat to 690-760°C, hold for sufficient time, then air cool. This eliminates stresses induced by normalizing, optimizes toughness and ductility, and achieves the final service properties.
3. Full Annealing (Optional)
Heat to 840-890°C, hold, then furnace cool to approximately 650°C, followed by air cooling to room temperature. Used to eliminate cold working stress or improve cold working formability.
Attention: Post-weld heat treatment (PWHT) must be performed after welding. It involves heating to 690-760 °C, holding at temperature, and then slow cooling to eliminate residual welding stresses and soften the heat-affected zone.
Due to its higher chromium and molybdenum content, P22 has a greater tendency for hardening in the weld heat-affected zone compared to P11. It is recommended to strictly control welding heat input and preheating temperature (200-300°C).
The heat treatment temperature and time must be strictly controlled to avoid grain coarsening or performance fluctuations.
Applicable Media
High-temperature steam
Main steam pipelines (≤550°C) of power plants, boiler headers, superheater tubes, and reheater tubes
Petroleum refining media
High-temperature and high-pressure process pipelines for atmospheric and vacuum distillation, catalytic cracking, hydrotreating, hydrocracking, etc.
High-pressure process gas
High-temperature and high-pressure pipelines for chemical equipment such as ammonia synthesis, methanol, and chemical fertilizers.
Hot water
Heat network, heating system.
Heat transfer oil and thermal carriers
Pipelines for chemical heat transfer systems
Note: ASTM A335 P22 is not suitable for strongly corrosive media such as strong oxidizing acids and high-temperature, high-concentration chlorides. Its upper oxidation temperature limit is approximately 565-580°C; P91 is recommended above this temperature. In high-temperature, high-pressure hydrogen-containing environments (such as hydrotreating units), the risk of hydrogen corrosion should be assessed. P22 is one of the commonly used materials for resisting hydrogen corrosion.
ASTM A335 P22 is suitable for high-temperature and high-pressure conditions ranging from 500 to 565°C. It is one of the preferred materials for supercritical power plants and oil refining hydrotreating units, and is recommended for use in the following areas:
Application Fields
-
Fossil Fuel Power Generation (Core Application)
● Main Steam Piping for Supercritical/Subcritical Power Plants (≤565°C)
● Boiler drum, superheater drum
● High-temperature steam pipelines, water supply pipelines
● Boiler heating surface tube system -
Petrochemical Engineering (Core Applications)
● High-temperature and high-pressure pipelines for hydrotreating/hydrocracking units in refineries
● Catalytic Reforming Unit Process Piping
● Atmospheric and Vacuum Distillation Unit High-Temperature Piping
● Delayed Coking Unit Process Piping -
Chemical and Fertilizer Industry
● High-temperature process pipelines for ammonia synthesis plants
● Methanol Plant Conversion Gas Pipeline
● High-temperature and high-pressure pipelines in chemical fertilizer plants -
Combined Heat and Power and Central Heating
● High-temperature steam pipeline of a thermal power plant
● Urban centralized heating high-temperature hot water pipeline -
High-temperature and high-pressure pipe fittings
● High-temperature elbows, tees, and reducers
● Forged pipe fittings, flanges
Delivery and Customization
We offer flexible and reliable supply chain solutions to ensure you receive ASTM A335 P22 alloy steel pipes that perfectly match your project requirements.
Customizable material forms
We support producing various basic and special shapes according to drawings or specifications.
|
Form |
 Seamless Steel Pipe
|
 Large-diameter Thick-walled Pipe
|
 Alloy Steel Pipe
|
|---|---|---|---|
|
Conventional Range |
Outer Diameter: 10.3 - 1067 mm; Wall Thickness: 1 - 150 mm |
Outer Diameter: 219 - 1067 mm; Wall Thickness: 20 - 150 mm |
Outer Diameter: 10.3 - 610 mm; Wall Thickness: 1 - 50 mm |
|
Customization Capability |
Hot-rolled / cold-drawn seamless tubes, fixed-length cutting, bevel machining, pipe end threads, special heat treatment conditions (normalizing + tempering / annealing) |
Hot expansion, fixed-length cutting, bevel machining, special heat treatment conditions |
Cold-drawn precision tubes, fixed-length cutting, special surface treatment |
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Full traceability across key QC checkpoints throughout production. 100% compliant with ASTM/ASME, EN, and GB standards. Material test reports available with every shipment.
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FAQ
Q: What are the main advantages of ASTM A335 P22?
Q: What is the difference between STM A335 P22 and P11? How to choose between them?
Q: What are the differences between ASTM A335 P22 and P91? How to choose between them?
Q: What is the maximum service temperature for ASTM A335 P22?
Q: What is the welding performance of ASTM A335 P22?
Q: What is the corrosion resistance of ASTM A335 P22?
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