Products Features
Good high-temperature strength and creep resistance (core advantage)
The core advantage of ASTM A335 P1 lies in its moderate high-temperature strength and creep resistance. Thanks to the addition of 0.5% molybdenum (Mo), P1 exhibits significantly superior high-temperature creep rupture strength compared to ordinary carbon steels (such as A106 Gr.B) within the temperature range of 350-500°C. Under 450°C conditions, the allowable stress of P1 is approximately 1.5 to 2 times that of carbon steel, 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 basic performance levels within the A335 series but offer significant advantages in terms of cost-effectiveness.
Excellent welding performance and heat treatment adaptability (differentiated advantage)
The welding performance of ASTM A335 P1 is superior to that of P11 and P22, which is an important reason for its preferential selection under specific operating conditions. Thanks to its lower alloy content and carbon equivalent (CE), P1 has a smaller tendency for hardening in the welding heat-affected zone, requires lower preheating temperatures before welding (typically 100-200°C), making it more user-friendly for on-site welding operations. Particularly in thin-walled pipe applications and situations where post-weld heat treatment cannot be performed immediately, P1 exhibits significantly better resistance to cold cracking compared to high-alloy grades. Its welding process is similar to that of ordinary carbon steel, resulting in lower operational difficulty for welders, making it suitable for large-scale on-site installation.
Good machinability and formability
The cold and hot working properties of ASTM A335 P1 are superior to those of P11 and P22, allowing for various forming processes such as hot bending, cold bending, and forging. Its lower alloy content reduces the risk of cracking during cold bending, making it suitable for manufacturing pipe fittings like elbows, tees, and reducers. Additionally, its machinability is better than that of high-alloy chromium-molybdenum steels, effectively lowering machining costs.
Cost-effective value proposition (distinct from the positioning of P11/P22)
ASTM A335 P1 is the grade with the lowest alloy content and the lowest cost per unit weight in the chromium-molybdenum alloy steel series. Compared to P11 (1.25Cr-0.5Mo), P1 has a chromium content of only 0.5% (approximately 40% of that of P11), resulting in significantly reduced alloy costs. For applications where operating temperatures are ≤450°C and higher oxidation resistance is not required, P1 serves as a high-value alternative to P11/P22, offering substantial material cost savings while maintaining high-temperature strength.
Good organizational stability and long-term service reliability
ASTM A335 P1 exhibits good microstructural stability during long-term service at temperatures up to 500°C. The addition of 0.5% Mo effectively enhances the material's high-temperature creep strength while inhibiting pearlite spheroidization and carbide coarsening, ensuring a low rate of mechanical property degradation over prolonged high-temperature service. After normalization plus tempering (N+T) heat treatment, P1 obtains a uniform and fine ferrite + pearlite microstructure, guaranteeing microstructural stability and reliability under high-temperature service conditions.
Technical Specifications
Chemical Composition(ASTM A335 / ASME SA335)
|
Element |
Standard requirements |
Note |
|
C |
0.08 - 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 |
0.15 - 0.35% |
Deoxidizer, improve high-temperature oxidation resistance |
|
Cr |
0.40 - 0.65% |
Core elements that provide basic antioxidant and corrosion resistance |
|
Mo |
0.44 - 0.65% |
Core elements to improve high-temperature creep fracture strength |
|
Fe |
Remaining quantity(≈ 97.5%) |
Matrix element |
Physical Properties
|
Performance |
Numerical Value/Range |
Test conditions |
|
Density |
≈ 7.85 g/cm³ |
Room Temperature (20°C) |
|
Melting Point |
≈ 1420-1460°C |
- |
|
Electrical resistance |
≈ 0.30 μΩ·m |
Room Temperature |
|
Thermal Conductivity |
≈ 42 W/(m·K) |
Room Temperature |
|
Coefficient of Thermal Expansion (20-100°C) |
≈ 12.2 × 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 |
≤ 163 HB (typical value) |
- |
Note: The strength level of P1 is the base grade in the ASTM A335 chromium-molybdenum steel series. Its advantages lie in good weldability, machinability, and cost-effectiveness, rather than pursuing the highest strength. For higher strength requirements, it is recommended to select P11 or P22.
High-temperature performance
ASTM A335 P1 maintains a high level of strength at elevated temperatures and is suitable for long-term high-temperature service conditions up to 450°C:
|
Temperature |
Tensile strength (MPa, approximately) |
Performance retention rate |
|
Room temperature (20°C) |
≥ 415 |
100% |
|
400°C |
≈ 350 |
≥ 84% |
|
450°C |
≈ 310 |
≥ 75% |
|
500°C |
≈ 260 |
≥ 63% |
Long-term Thermal Stability and Microstructural Stability:
ASTM A335 P1 exhibits good microstructural stability during long-term service at temperatures ≤500°C. The addition of 0.5% Mo effectively enhances high-temperature creep strength. However, when used for extended periods above 550°C, its microstructural stability decreases and creep strength significantly drops; thus, it is not recommended for long-term service above 550°C. For higher temperature grades, P11 or P22 are suggested.
Heat treatment system
The final performance of ASTM A335 P1 is highly dependent on the heat treatment regime, with common specifications as follows:
1. Normalizing Treatment (Normalizing):
Heat to 900-955°C, hold for a sufficient time (approximately 1 hour per inch of wall thickness), then air cool. This results in a uniform fine ferrite + pearlite microstructure, preparing it for subsequent tempering.
2. Tempering treatment(Tempering)：
Heat to 620-750°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 870-900°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) is recommended after welding. It involves heating to 620-750°C, holding at temperature, and then slow cooling to eliminate residual welding stresses and soften the heat-affected zone.
The heat treatment temperature and time must be strictly controlled to avoid grain coarsening or performance fluctuations.
For thin-walled tubes or small-diameter tubes, the insulation time can be appropriately shortened.
Applicable Media
1. High-temperature steam:
main steam pipelines of power plants, boiler headers, superheater tubes, reheater tubes
2. High-temperature hot water:
Heat network, heating system
3. Petroleum Refining Medium：
High-temperature process pipelines for atmospheric and vacuum distillation, catalytic cracking, hydrotreating, etc.
4. High-pressure process gas：
High-temperature and high-pressure pipelines for chemical equipment such as synthetic ammonia, methanol, and fertilizers
5. Heat transfer oil and heat carriers
ASTM A335 P1 is not suitable for strongly corrosive media such as strong oxidizing acids and high-temperature, high-concentration chlorides. Its upper limit for oxidation resistance is approximately 500-550°C; P11 or P22 is recommended above this temperature. In high-temperature hydrogen-containing environments, the risk of hydrogen corrosion should be evaluated.
ASTM A335 P1 is suitable for high-temperature and high-pressure conditions ranging from 350 to 500°C. It is the most cost-effective and weldable base grade in the chromium-molybdenum steel series, recommended for use in the following fields:
Application Fields
-
Fossil Fuel Power Generation (Core Application)
● Main Steam Pipeline of Subcritical Power Plant (≤450°C)
● Boiler drum, superheater drum
● High-temperature steam pipelines, water supply pipelines
● Boiler heating surface tube system -
Petrochemical Engineering (Core Applications)
● High-temperature pipelines of the atmospheric and vacuum distillation unit in a refinery
● Catalytic Cracking Unit Process Piping
● High-temperature and high-pressure pipelines in hydrotreating units
● 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 network 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 P1 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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We provide free samples for quality verification, allowing you to place bulk orders only after approval. We ensure consistency from sample to mass production by accurate dimensional measurement and transparent manufacturing.
FAQ
Q: What are the main advantages of ASTM A335 P1?
Q: What is the difference between ASTM A335 P1 and P11? How to choose between them?
Q: What is the maximum service temperature for ASTM A335 P1?
Q: What is the welding performance of ASTM A335 P1?
Q: What is the corrosion resistance of ASTM A335 P1?
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