ASTM A335 P91
ASTM A335 P91 Alloy Steel Pipe Supplier in Tunisia
ASTM A335 P91 is a high-performance ferritic alloy steel grade used for seamless pipes designed for high-temperature service. It contains chromium, molybdenum and vanadium, along with controlled additions of other elements that contribute to its elevated-temperature strength and creep resistance.
The ASTM A335/A335M specification covers seamless ferritic alloy-steel pipe intended for high-temperature applications. Grade P91 is commonly used in selected power generation and industrial steam systems where demanding temperature, pressure and service-life requirements influence material selection.
Emirerri Steel supports industrial procurement requirements for ASTM A335 P91 alloy steel pipes based on project specifications, dimensions, inspection requirements and availability.
Key Features
- Advanced alloy composition: Chromium-molybdenum-vanadium steel with controlled microalloying elements.
- High-temperature strength: Designed for specified applications involving elevated operating temperatures.
- Creep resistance: Suitable for engineering applications involving sustained stress at high temperatures.
- Seamless construction: Manufactured without a longitudinal weld seam.
- Controlled heat treatment: Essential for achieving the required microstructure and mechanical properties.
- Material traceability: Testing and documentation can be supplied according to applicable standards and purchase requirements.
Specifications
| Parameter | Description |
|---|---|
| Standard | ASTM A335/A335M |
| Grade | P91 |
| Material family | Ferritic chromium-molybdenum-vanadium alloy steel |
| Product type | Seamless alloy steel pipe |
| Service category | High-temperature service |
| Outside diameter | As specified in the purchase order |
| Wall thickness | According to schedule or project requirements |
| Length | As specified in the order |
| End preparation | Plain, bevelled or as specified |
| Heat treatment | According to applicable specification requirements |
| Inspection | According to the governing standard and purchase order |
| Certification | Material test certificate, subject to order requirements |
Dimensions, tolerances, heat-treatment conditions and testing requirements must be confirmed against the applicable ASTM A335/A335M edition and the project specification.
ASTM A335 P91 – Chemical Composition
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.08–0.12 |
| Manganese (Mn) | 0.30–0.60 |
| Phosphorus (P) | 0.020 Max. |
| Sulfur (S) | 0.010 Max. |
| Silicon (Si) | 0.20–0.50 |
| Chromium (Cr) | 8.00–9.50 |
| Molybdenum (Mo) | 0.85–1.05 |
| Vanadium (V) | 0.18–0.25 |
| Nickel (Ni) | 0.40 Max. |
| Niobium (Nb) | 0.06–0.10 |
| Nitrogen (N) | 0.03–0.07 |
| Aluminum (Al) | 0.04 Max. |
ASTM A335 P91 – Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength | 585 MPa (85 ksi) Min. |
| Yield Strength | 415 MPa (60 ksi) Min. |
| Elongation | 20% Min. |
| Reduction of Area | 40% Min. |
| Brinell Hardness | 250 HBW Max. |
ASTM A335 P91 – Physical Properties
| Property | Typical Value |
|---|---|
| Density | Approx. 7.75–7.80 g/cm³ |
| Melting Range | Approx. 1,425–1,510°C |
| Modulus of Elasticity | Approx. 210 GPa |
| Thermal Conductivity | Approx. 25–30 W/m·K |
| Specific Heat Capacity | Approx. 460–500 J/kg·K |
| Coefficient of Thermal Expansion | Approx. 11–13 × 10⁻⁶/°C |
| Magnetic Properties | Magnetic |
High-Temperature Performance
ASTM A335 P91 is used in selected industrial installations where elevated-temperature strength and resistance to creep deformation are important.
Material selection should account for:
Design and operating temperatures
Internal pressure and mechanical loading
Duration of exposure to elevated temperatures
Start-up, shutdown and thermal cycling conditions
Welding and heat-treatment requirements
Applicable piping codes and inspection criteria
The maximum allowable operating temperature and pressure must be established using the governing design code and engineering data. These limits cannot be determined from the grade designation alone.
Applications
Power Generation
Specified high-temperature steam piping
Thermal power plant piping systems
Selected high-temperature process lines
Oil and Gas
Selected refinery process systems
Industrial piping designed for the grade’s service conditions
Specified high-temperature installations
Petrochemical and Process Industries
High-temperature process piping
Industrial heating systems
Selected thermal-service installations
The suitability of ASTM A335 P91 must be confirmed against the process conditions, design code and project-specific material requirements.
Oxidation and Corrosion Resistance
The chromium content of ASTM A335 P91 contributes to its oxidation behaviour under suitable high-temperature conditions. However, P91 is a ferritic alloy steel, not a stainless steel grade.
Its corrosion performance depends on the process fluid, temperature, moisture and operating environment. For corrosive service, compatibility should be evaluated against the actual conditions and applicable engineering requirements.
Welding and Fabrication
Welding and fabrication of ASTM A335 P91 require careful control to preserve the material’s specified microstructure and mechanical properties.
Key considerations include:
Qualified welding procedures, where required
Compatible welding consumables
Preheating according to the approved procedure
Post-weld heat treatment, when required
Non-destructive examination according to the governing code
Hardness verification and material traceability, where specified
Welding and heat-treatment parameters must be established by qualified specialists according to the pipe dimensions, joint design, approved procedure and operating conditions. Improper fabrication may compromise the material’s intended performance.
ASTM A335 P91 vs. P22
ASTM A335 P91 and P22 are alloy-steel pipe grades used in selected high-temperature applications, but they have different compositions and specified properties.
ASTM A335 P22: Chromium-molybdenum alloy steel used in selected thermal and industrial applications.
ASTM A335 P91: Chromium-molybdenum-vanadium alloy steel designed for specific applications requiring enhanced high-temperature strength and creep performance.
Selection depends on the design code, operating temperature, pressure, service life, fabrication requirements and project economics. These grades should not be substituted for one another without engineering approval.
Quality Control and Certification
Depending on the applicable standard and purchase order, quality assurance for ASTM A335 P91 pipe may include:
Material test certificate
Chemical composition analysis
Mechanical testing
Dimensional inspection
Visual examination
Non-destructive testing, where required
Heat-treatment records, where applicable
Product marking and material traceability
The actual testing scope and documentation must be agreed with the manufacturer and specified in the purchase order.
Emirerri Steel – ASTM A335 P91 Alloy Steel Pipe Supplier
Emirerri Steel supports industrial buyers in the power generation, oil and gas, refining, petrochemical and process industries.
We can review enquiries for ASTM A335 P91 seamless alloy steel pipes based on required outside diameters, wall thicknesses, schedules, lengths, quantities, inspection requirements and delivery destinations.
Supply is subject to the agreed technical specification, manufacturer capability and availability. Other alloy steel pipe grades can also be considered according to project requirements.
Conclusion
ASTM A335 P91 is a seamless ferritic alloy steel pipe grade intended for specified high-temperature applications requiring carefully controlled mechanical and metallurgical properties. Proper selection requires verification of the applicable standard, design conditions, heat treatment and material documentation.
Contact Emirerri Steel to discuss your requirements for ASTM A335 P91 alloy steel pipes and other industrial piping materials.
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