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High-Temperature Seamless Ferritic Alloy-Steel Pipes - ASTM A335 Suppliers & Factory in China
Ordering Information
Purchasers must specify the following when ordering:
- Quantity (length or number of pipes)
- Material grade (e.g., P11, P22, P91)
- Size (NPS or DN and schedule or wall thickness)
- Length (random or specific)
- ASTM designation (A335 or A335M for metric units)
- Optional requirements (e.g., additional testing, special finishes)
- Any supplementary requirements (S1–S7)
Material and Manufacture
- Process: Pipes shall be made by seamless process (hot-worked or cold-worked followed by heat treatment).
- Heat Treatment: All pipes must undergo proper heat treatment (e.g., normalization, tempering) to meet mechanical properties.
Chemical Composition
Each grade has specific limits for carbon, manganese, phosphorus, sulfur, silicon, chromium, molybdenum, and other alloying elements.
Mechanical Properties
- Tensile Strength, Yield Strength, and Elongation: Requirements vary by grade (e.g., P91: min. tensile strength 585 MPa, yield strength 415 MPa).
- Hardness Testing: Optional unless specified.
Test Requirements
- Hydrostatic Testing: Each pipe must withstand a specified hydrostatic pressure without leakage.
- Nondestructive Electric Testing (NDE): Optional unless required (e.g., eddy current, ultrasonic testing).
- Flattening Test, Bend Test, or Flange Test: Required for certain sizes and grades.
- Impact Testing: Required if specified (e.g., for low-temperature service).
Inspection & Certification
- Manufacturer must perform tests and provide a Certificate of Compliance.
- Third-party inspection may be required if specified in the purchase order.
Marking
Each pipe must be marked with:
- Manufacturer's name or trademark
- ASTM designation (A335 or A335M)
- Grade (e.g., P11, P22)
- Heat number
- Size and schedule
Supplementary Requirements
Optional additional tests (e.g., grain size analysis, special NDE methods) may be specified.
Keywords
Seamless pipe, alloy steel, high-temperature service, ferritic steel, P-grade steels.
Main Grades in ASTM A335/A335M
| Grade | UNS Number | Key Alloy Composition | Common Applications |
|---|---|---|---|
| P1 | K11522 | 0.5Mo | Low-alloy boilers, piping |
| P2 | K11547 | 0.5Cr-0.5Mo | Power plants, refineries |
| P5 | K41545 | 5Cr-0.5Mo | High-temp/pressure service |
| P9 | S50400 | 9Cr-1Mo | Petrochemical, boilers |
| P11 | K11597 | 1.25Cr-0.5Mo-Si | Power generation, steam lines |
| P12 | K11562 | 1Cr-0.5Mo | Similar to P11, boilers |
| P21 | K31545 | 3Cr-1Mo | High-temp strength |
| P22 | K21590 | 2.25Cr-1Mo | Widely used in power plants |
| P91 | K91560 | 9Cr-1Mo-V-Nb | Advanced high-temp/pressure |
| P92 | K92460 | 9Cr-2W-0.5Mo-V-Nb | Ultra-supercritical boilers |
| P122 | K91640 | 11Cr-2W-1Cu-Mo-V-Nb | High-efficiency power plants |
📌 Key Notes
- Grades P5 to P92 are chromium-molybdenum (Cr-Mo) steels, offering increasing resistance to oxidation and creep at elevated temperatures.
- P91, P92, and P122 are advanced high-strength steels used in modern power plants for ultra-supercritical (USC) applications.
- P1 and P2 are lower-alloy grades for less severe conditions.
These grades are selected based on temperature, pressure, and corrosion resistance requirements in industries like power generation, oil & gas, and petrochemical plants.
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Frequently Asked Questions (FAQ)
Q What is ASTM A335 / A335M?
ASTM A335 / A335M is the standard specification for seamless ferritic alloy-steel pipe intended for high-temperature service. It covers multiple P-grade steels used in power generation, refineries, and petrochemical plants where elevated temperature and pressure resistance are critical.
Q What are the most commonly used grades of ASTM A335?
The most widely used grades include P11, P22, P91, and P92. P11 and P22 are popular in conventional power plants, while P91 and P92 are preferred for advanced ultra-supercritical (USC) boiler applications due to their superior high-temperature strength and creep resistance.
Q What manufacturing process is required for ASTM A335 pipes?
All ASTM A335 pipes must be produced by the seamless process, either hot-worked or cold-worked. Following forming, pipes must undergo appropriate heat treatment — such as normalization and tempering — to achieve the required mechanical properties for each grade.
Q What testing is required for ASTM A335 pipes?
Each pipe must pass a hydrostatic test without leakage. Additional tests — including flattening, bend, or flange tests — are required for specific sizes and grades. Nondestructive electric testing (NDE) such as ultrasonic or eddy current testing, as well as impact testing, may also be required depending on the purchase order.
Q What markings are required on ASTM A335 pipes?
Each ASTM A335 pipe must be clearly marked with the manufacturer's name or trademark, ASTM designation (A335 or A335M), material grade (e.g., P11, P22), heat number, and the pipe size and schedule to ensure full traceability and compliance.
Q What is the difference between P91 and P92 grades?
Both P91 and P92 are advanced 9% chromium steels for high-temperature service. P91 (9Cr-1Mo-V-Nb) is a well-established grade offering excellent creep strength. P92 (9Cr-2W-0.5Mo-V-Nb) adds tungsten to improve creep resistance further, making it suitable for ultra-supercritical (USC) boiler applications at even higher operating temperatures and pressures.