Introduction:
ASME SA335 Grade P91 alloy steel pipes are among the most critical components in high-temperature, high-pressure environments such as power plants, petrochemical units, and refineries. Known for their superior creep strength, oxidation resistance, and thermal stability, these pipes are designed to handle the most demanding engineering applications.
At Mcneil Instrument, we stand as one of the leading manufacturers, suppliers, and exporters of P91 alloy steel pipes in India, offering high-performance solutions to industries worldwide. Our products are ASME, ASTM, and ISO certified, tested, and proven for efficiency in elevated temperature operations.
Why Choose ASME SA335 Grade P91 Alloy Steel Pipes?
P91 alloy steel is a ferritic alloy enhanced with chromium and molybdenum. What sets it apart is the addition of vanadium and niobium, which improves creep rupture strength significantly. These pipes are widely preferred in supercritical and ultra-supercritical boiler systems, offering both durability and cost efficiency.
Key Advantages:
- Exceptional high-temperature strength
- High resistance to thermal fatigue and oxidation
- Excellent weldability and fabrication properties
- Long service life in steam service lines and pressure vessels
Technical Specifications & Mechanical Properties
| Specification | Details |
| Standard | ASME SA335 / ASTM A335 |
| Grade | P91 |
| Type | Seamless Alloy Steel Pipes |
| Material Composition | 9% Chromium, 1% Molybdenum, Vanadium, Niobium |
| Manufacturing Process | Hot finished or cold drawn |
| Size Range | 1/2” NB to 36” NB |
| Thickness | SCH 40, SCH 80, SCH 160, XXS |
| Length | Single/Double Random, Cut Length |
Mechanical Properties
| Property | Value |
| Tensile Strength | ≥ 585 MPa |
| Yield Strength | ≥ 415 MPa |
| Elongation | ≥ 20% |
| Hardness (HBW) | ≤ 250 |
| Impact Test | As per customer requirement |
Applications of P91 Alloy Steel Pipes
P91 alloy steel pipes are engineered for extreme service conditions. They are extensively used in:
- Thermal and nuclear power plants
- Steam pipelines and high-pressure boilers
- Petrochemical and oil refineries
- Superheater and reheater tubes
- Heat exchangers and pressure vessels
These applications demand high thermal efficiency, which P91 delivers through its low thermal expansion and high oxidation resistance.
Dimensions & Wall Thickness Chart
| Nominal Pipe Size | Outside Diameter (mm) | Wall Thickness (mm) |
| 1/2″ | 21.3 | 2.77 – 3.73 |
| 1″ | 33.4 | 3.38 – 4.55 |
| 2″ | 60.3 | 5.54 – 8.74 |
| 4″ | 114.3 | 6.02 – 13.49 |
| 8″ | 219.1 | 8.18 – 20.24 |
| 12″ | 323.9 | 10.31 – 25.40 |
Certifications
All P91 alloy steel pipes from Mcneil Instrument are supplied with full documentation, including:
- EN 10204 3.1 & 3.2 Mill Test Certificates
- IBR and NACE Compliance
- PED (Pressure Equipment Directive)
- ISO 9001:2015 Certification
- Third-party Inspection Approvals (TPI) on request
Available Sizes & Specifications
| Size Range | 1/2” NB to 36” NB |
| Wall Thickness | SCH 10 to XXS |
| Schedule | SCH 40, SCH 80, SCH 160, etc. |
| End Types | Plain End, Bevel End, Threaded |
| Finish | Annealed, Pickled, Polished |
| Delivery Condition | Hot Rolled / Cold Drawn |
Global Reach of Mcneil Instrument: ASME SA335 Grade P91 Alloy Steel Pipes
Mcneil Instrument proudly exports top-grade ASME SA335 Grade P91 alloy steel pipes to critical industries around the world, where high-temperature and high-pressure performance is non-negotiable:
- In Saudi Arabia, our P91 pipes are deployed in supercritical thermal power plants and refineries, where long-term performance under extreme heat is vital.
- In Qatar, we supply gas processing and petrochemical facilities, offering pipes that resist thermal fatigue and pressure fluctuations.
- In Nigeria, Mcneil supports industrial boiler systems and steam lines, providing durable P91 alloy pipes with certified mechanical integrity.
- Across Ghana, our pipes power energy recovery and high-pressure feedwater applications, ensuring safety and efficiency in demanding setups.
- In Texas, we serve high-efficiency coal and combined-cycle plants, where P91’s elevated creep strength ensures long service life.
- In Chicago, our P91 alloy pipes are trusted in heavy-duty process plants and turbine systems, delivering compliance with ASME and ASTM standards.
- In Malaysia, Mcneil provides P91 seamless pipes for heat exchangers and pressure vessels used in the oil & gas sector.
- In Singapore, we support marine steam systems and industrial boilers, where corrosion resistance and weldability are key.
- In Brazil, our P91 pipes are exported to chemical plants and pulp & paper mills, maintaining thermal stability in corrosive environments.
Conclusion
With industry-leading manufacturing capabilities, certified quality, and a strong global network, Mcneil Instrument is your most reliable partner for ASME SA335 Grade P91 Alloy Steel Pipes. Whether your project demands high strength, durability, or elevated temperature tolerance, our pipes meet the highest standards of performance and compliance.
