SA335 P91 Alloy Steel Pipe


SA335 P91 Alloy Steel Pipe

SA335 P91 is a high-temperature, high-pressure alloy steel pipe designed for use in various industrial applications, particularly in power plants and petrochemical plants. This alloy is known for its excellent strength, resistance to corrosion, and ability to withstand high temperatures.

Product Specifications

Material Composition

  • Grade: P91
  • Standard: ASTM A335 / ASME SA335
  • Main Alloying Elements: Chromium (Cr), Molybdenum (Mo), and Vanadium (V)
  • Typical Chemical Composition:
    • Carbon (C): 0.08-0.12%
    • Manganese (Mn): 0.30-0.60%
    • Phosphorus (P): ≤0.02%
    • Sulfur (S): ≤0.01%
    • Silicon (Si): 0.20-0.50%
    • Chromium (Cr): 8.0-9.5%
    • Molybdenum (Mo): 0.85-1.05%
    • Vanadium (V): 0.18-0.25%
    • Nickel (Ni): ≤0.40%
    • Copper (Cu): ≤0.40%
    • Nitrogen (N): 0.03-0.07%
    • Aluminum (Al): ≤0.02%
    • Niobium (Nb): 0.06-0.10%

Mechanical Properties

  • Tensile Strength: ≥585 MPa (85 ksi)
  • Yield Strength: ≥415 MPa (60 ksi)
  • Elongation: ≥20%
  • Hardness: ≤250 HBW


A335 Gr P91 Seamless Steel Pipe Chemical Composition:

Grade UNS Designation Chemical Composition %
P91 Type 1 K91560 C Mn P S Si Ni Cr Mo
0.08-0.12 0.30-0.60 0.020 0.010 0.20-0.50 0.40 max 8.00-9.50 0.85-1.05
V N Al Cb Ti Zr Sn Sb
0.18-0.25 0.030-0.070 0.02 max 0.06-010 0.01 max 0.01 max _ _
P91 Type 2 K91560 C Mn P S Si Ni Cr Mo
0.08-0.12 0.30-0.50 0.020 0.005 0.20-0.40 0.40 max 8.00-9.50 0.85-1.05
V N Al Cb Ti Zr Sn Sb
0.18-0.25 0.035-0.070 0.02 max 0.06-0.10 0.01 max 0.01 max 0.010 max 0.003 max

A335 Gr P91 Seamless Steel Pipe Mechanical Capacity:

Grade Tensile Strength min ksi(MPa) Yield Strength min ksi (MPa) Elongation (%)
P91 85(585) 60(415) 20




● Mill Test Report: according to EN10204.3.1


● Nondestructive Examination

● Flattening Test

● Mechanical Test

● Transverse Tension Test

● Metal Structure and Etching Test

Size Range

  • Outside Diameter (OD): 19.05 mm (3/4″) to 114.3 mm (4 1/2″)
  • Wall Thickness (WT): 2.0 mm to 14 mm
  • Length: Single Random Length (SRL), Double Random Length (DRL), or as specified

Manufacturing Process

  • Seamless: SA335 P91 pipes are typically manufactured using the seamless process, ensuring high strength and durability.
  • Heat Treatment: Normalized and tempered to achieve the desired mechanical properties.

Key Benefits

  • High Temperature Resistance: P91 alloy steel pipes can withstand high temperatures, making them ideal for use in power generation and petrochemical industries.
  • Excellent Strength: The alloying elements provide superior tensile and yield strength, ensuring reliable performance under high pressure.
  • Corrosion Resistance: Chromium and molybdenum enhance the pipe’s resistance to oxidation and corrosion, increasing its longevity.
  • Weldability: P91 pipes can be welded using appropriate methods, ensuring strong and durable joints.

Typical Applications

Power Plants

  • Usage: P91 pipes are used in high-temperature superheater and reheater tubes, headers, and steam lines in power plants.
  • Benefits: Their ability to withstand high temperatures and pressures ensures efficient and safe operation of power generation equipment.

Petrochemical Plants

  • Usage: These pipes are used in catalytic cracking units, hydrocrackers, and other high-temperature processing equipment.
  • Benefits: The alloy’s resistance to corrosion and oxidation makes it ideal for handling various chemicals and hydrocarbons.

Boilers and Pressure Vessels

  • Usage: P91 pipes are used in the construction of boilers and pressure vessels, where high temperature and pressure conditions are prevalent.
  • Benefits: The material’s high strength and durability ensure the safety and reliability of these critical components.


SA335 P91 alloy steel pipes are a premier choice for high-temperature and high-pressure applications in power plants, petrochemical plants, and other industrial settings. Their superior mechanical properties, excellent resistance to corrosion, and ability to withstand extreme conditions make them indispensable in ensuring the efficiency and safety of critical infrastructure. By adhering to stringent manufacturing standards and quality control measures, P91 pipes provide reliable performance and long service life in demanding environments.



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