ASTM A335 P91 Pipes | ASME SA335 P91 Alloy Steel Seamless Pipes
Welcome to ASC LLP, your trusted partner in premium quality alloy seamless pipes. In this comprehensive guide, we delve into the exceptional features and advantages of ASTM A335 P91 Alloy Seamless Pipes. These pipes are essential components in various industrial applications due to their unparalleled properties and performance.
What are ASTM A335 P91 Pipes?
ASTM A335 P91 Pipes, classified under the A335/SA335 P91 specification, are seamless ferritic alloy steel pipes designed for high-temperature services. These pipes are often used in power plants, refineries, petrochemical industries, and more due to their excellent resistance to oxidation and corrosion. They come in two types: ASTM A335 P91 Type 1 and ASTM A335 P91 Type 2, each offering unique benefits.
UNS K91560: The Alloy Behind P91 Pipes
The designation UNS K91560 refers to the alloy composition of P91 pipes. This material consists of a fine balance of elements like chromium, molybdenum, and vanadium, providing the strength and durability required for demanding environments.

Properties of ASTM A335 P91 Alloy Seamless Pipes
ASTM A335 P91 Alloy Seamless Pipes possess several unique properties that make them stand out:
- High Tensile Strength: These pipes exhibit excellent tensile strength, ensuring they can withstand high pressure and stress without deforming or failing.
- Superior Creep Resistance: P91 pipes offer exceptional resistance to creep, which is the tendency of a material to deform permanently under mechanical stress, particularly at high temperatures.
- Thermal Stability: These pipes maintain their structural integrity and performance at elevated temperatures, making them ideal for high-temperature applications.
- Corrosion Resistance: The chromium content in the alloy enhances its resistance to oxidation and corrosion, extending the service life of the pipes even in harsh environments.
- Durability: The combination of elements in P91 alloy gives it exceptional toughness and durability, ensuring a long service life.
Advantages of ASTM A335 P91 Alloy Seamless Pipes
Choosing ASTM A335 P91 Alloy Seamless Pipes offers numerous advantages:
- Efficiency in High-Temperature Applications: Their ability to maintain strength and stability at high temperatures makes them indispensable in power generation and chemical processing industries.
- Enhanced Safety: The high tensile strength and durability reduce the risk of failures, ensuring safer operation in critical applications.
- Long Service Life: Due to their resistance to corrosion and oxidation, these pipes have a longer service life, reducing the need for frequent replacements and maintenance.
- Cost-Effectiveness: Although the initial investment might be higher, the longevity and reliability of P91 Alloy Seamless Pipes make them a cost-effective choice in the long run.
- Compliance with Standards: These pipes meet the stringent ASTM A335 specifications, ensuring they adhere to global quality and safety standards.
Specifications of A335/SA335 P91 Pipes
- Standard: ASTM A335 / ASME SA335
- Grade: P91
- Type: Seamless
- Material: Alloy Steel
- UNS Designation: K91560
- Available Sizes: 1/2” NB to 24” NB
- Thickness: SCH 40 to SCH XXS
- Ends: Plain End, Beveled End, Threaded End


Schedule and Size Chart for ASTM A335 P91 Pipes
Schedule | Nominal Pipe Size (NPS) | Outside Diameter (OD) (inches) | Wall Thickness (inches) |
SCH 40 | 1/2″ – 24″ | 0.84″ – 24.00″ | 0.109″ – 0.688″ |
SCH 80 | 1/2″ – 24″ | 0.84″ – 24.00″ | 0.147″ – 1.500″ |
SCH 160 | 1/2″ – 24″ | 0.84″ – 24.00″ | 0.188″ – 2.500″ |
SCH XXS | 1/2″ – 24″ | 0.84″ – 24.00″ | 0.294″ – 3.000″ |
Mechanical Properties Chart for ASTM A335 P91 Pipes
Property | Value |
Tensile Strength | ≥ 585 MPa (85 ksi) |
Yield Strength | ≥ 415 MPa (60 ksi) |
Elongation | ≥ 20% |
Hardness | ≤ 250 HB |
Tensile Strength Chart for UNS K91560
Size Range (NPS) | Tensile Strength (MPa) | Tensile Strength (ksi) |
1/2″ – 2″ | ≥ 585 MPa | ≥ 85 ksi |
2 1/2″ – 6″ | ≥ 585 MPa | ≥ 85 ksi |
8″ – 24″ | ≥ 585 MPa | ≥ 85 ksi |
Heat Treatment Requirement Chart for ASME SA335 P91 Pipes
Heat Treatment Process | Temperature Range (°C) | Temperature Range (°F) | Duration |
Normalizing | 1040 – 1080 | 1900 – 1975 | 1 hour |
Tempering | 760 – 780 | 1400 – 1435 | 1 hour |
Chemical Composition Chart for UNS K91560
Element | Composition (%) |
Carbon (C) | 0.08 – 0.12 |
Chromium (Cr) | 8.0 – 9.5 |
Molybdenum (Mo) | 0.85 – 1.05 |
Vanadium (V) | 0.18 – 0.25 |
Manganese (Mn) | 0.30 – 0.60 |
Silicon (Si) | 0.20 – 0.50 |
Phosphorus (P) | ≤ 0.025 |
Sulfur (S) | ≤ 0.010 |
Nickel (Ni) | ≤ 0.40 |
Nitrogen (N) | 0.03 – 0.07 |
Physical Properties Chart for ASME SA335 P91 Pipes
Property | Value |
Density | 7.8 g/cm³ |
Melting Point | 1370 – 1450 °C |
Thermal Conductivity | 24 W/m·K at 20 °C |
Specific Heat Capacity | 460 J/kg·K |
Electrical Resistivity | 1.25 µΩ·m at 20 °C |
Application Chart for ASTM A335 P91 Pipes
Application Area | Specific Uses |
Power Generation | Boilers, steam pipelines, superheaters |
Petrochemical Industry | Refineries, chemical processing units |
Oil and Gas Industry | Drilling, production processes, pipelines |
Industrial Boilers | High-temperature and high-pressure boilers |
Heat Exchangers | Tubes for heat exchangers |
Process Piping | High-temperature process piping systems |
Why Choose ASC LLP for ASTM A335 P91 Alloy Seamless Pipes?
At ASC LLP, we pride ourselves on being a leading supplier of premium quality alloy seamless pipes. Here’s why you should choose us:
- Unmatched Quality: We ensure that our P91 Alloy Seamless Pipes meet the highest quality standards, offering you reliability and peace of mind.
- Extensive Inventory: We maintain a large inventory of alloy pipes in various sizes and specifications to meet your immediate requirements.
- Expertise and Experience: With years of experience in the industry, we provide expert guidance and support to help you choose the right piping solutions for your needs.
- Competitive Pricing: We offer competitive prices without compromising on quality, ensuring you get the best value for your investment.
- Timely Delivery: Our efficient logistics network ensures that your orders are delivered on time, every time.
ASTM A335 P91 Alloy Seamless Pipes are the go-to solution for high-temperature and high-pressure applications across various industries. Their exceptional properties and advantages make them an indispensable component in power generation, petrochemical, and industrial processing sectors. At ASC LLP, we are committed to providing you with the highest quality alloy pipes to meet your specific needs. Contact us today to learn more about our products and services, and let us help you find the perfect piping solution for your project.
Global Reach
Amardeep Steel Centre boasts a robust global presence, committed to delivering unparalleled service and quality to clients around the world. Our dedication to prompt delivery and exceptional customer care sets us apart in the industry. Major corporations across the USA, Europe, Asia, and other regions place their trust in our high-quality ASTM A335 P91 Alloy Seamless Pipes. This widespread trust underscores our reputation for reliability and excellence. By consistently meeting and exceeding the expectations of our international clientele, we continue to solidify our position as a leader in the global steel market.

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