In demanding environments like power plants, oil refineries, and petrochemical industries, ordinary pipes can fail under intense heat and pressure. This is where ASTM A335 alloy steel pipes—particularly grades P5, P9, P11, P22, and P91—come into play. These pipes are engineered to handle extreme conditions without compromising structural integrity or performance.
As a trusted manufacturer, supplier, and exporter in India, Mcneil Instrument is recognized for delivering high-grade ASTM A335 pipes that meet international standards for thermal resistance, strength, and durability. This blog will explore the significance of these grades and why Mcneil Instrument is your best choice.
What Is ASTM A335?
ASTM A335 is a specification for seamless ferritic alloy-steel pipe intended for high-temperature services. The “P” grades under this standard—P5, P9, P11, P22, and P91—are defined by different combinations of chromium, molybdenum, and other alloying elements that enhance their thermal stability and corrosion resistance.
Key Properties of ASTM A335 Pipes:
- Excellent performance in elevated temperatures
- Enhanced creep resistance
- Strong oxidation and corrosion resistance
- Suitable for boiler systems, heat exchangers, and superheaters
Grade-Wise Overview of ASTM A335 Pipes by Mcneil Instrument
| Grade | Applications | Advantages |
| ASTM A335 P5 | Oil refineries, fertilizer plants | High chromium content, oxidation resistance, strength under pressure |
| ASTM A335 P9 | Heat exchangers, power stations | Balanced strength and ductility, thermal stability, corrosion resistance |
| ASTM A335 P11 | Steam pipelines, industrial heaters | Versatile, easy weldability, cost-effective |
| ASTM A335 P22 | Pressure vessels, nuclear plants | Improved creep strength, long service life, high-heat reliability |
| ASTM A335 P91 | Supercritical boilers, power generation | Exceptional tensile strength, oxidation resistance at high temperatures |
Specifications and Standards – ASTM A335 P5, P9, P11, P22, P91 Pipes
| Grade | Main Elements | Applications | Temp. Resistance |
| P5 | 5% Chromium, 0.5% Moly | Refineries, High-pressure lines | High |
| P9 | 9% Chromium | Power generation, Heat exchangers | High |
| P11 | 1.25% Chromium, 0.5% Moly | Boilers, Steam piping | Medium |
| P22 | 2.25% Chromium, 1% Moly | Nuclear, Heavy-duty piping | High |
| P91 | 9% Chromium, 1% Moly + V/N | Supercritical Boilers, Energy plants | Very High |
ASTM A335 P5, P9, P11, P22, P91 Pipes – Size Chart
| Nominal Pipe Size (NPS) | Outside Diameter (OD) | Wall Thickness (SCH 40) | Wall Thickness (SCH 80) | Standard Lengths |
| 1/2″ | 21.3 mm | 2.77 mm | 3.73 mm | 5.8m / 6m / 12m |
| 3/4″ | 26.7 mm | 2.87 mm | 3.91 mm | 5.8m / 6m / 12m |
| 1″ | 33.4 mm | 3.38 mm | 4.55 mm | 5.8m / 6m / 12m |
| 1 1/4″ | 42.2 mm | 3.56 mm | 4.85 mm | 5.8m / 6m / 12m |
| 1 1/2″ | 48.3 mm | 3.68 mm | 5.08 mm | 5.8m / 6m / 12m |
| 2″ | 60.3 mm | 3.91 mm | 5.54 mm | 5.8m / 6m / 12m |
| 2 1/2″ | 73.0 mm | 5.16 mm | 7.01 mm | 5.8m / 6m / 12m |
| 3″ | 88.9 mm | 5.49 mm | 7.62 mm | 5.8m / 6m / 12m |
| 4″ | 114.3 mm | 6.02 mm | 8.56 mm | 5.8m / 6m / 12m |
| 6″ | 168.3 mm | 7.11 mm | 10.97 mm | 5.8m / 6m / 12m |
| 8″ | 219.1 mm | 8.18 mm | 12.70 mm | 5.8m / 6m / 12m |
| 10″ | 273.0 mm | 9.27 mm | 15.09 mm | 5.8m / 6m / 12m |
| 12″ | 323.8 mm | 9.53 mm | 17.48 mm | 5.8m / 6m / 12m |
| 14″ | 355.6 mm | 9.53 mm | 17.12 mm | 5.8m / 6m / 12m |
| 16″ | 406.4 mm | 9.53 mm | 18.26 mm | 5.8m / 6m / 12m |
| 18″ | 457.0 mm | 9.53 mm | 19.05 mm | 5.8m / 6m / 12m |
| 20″ | 508.0 mm | 9.53 mm | 19.05 mm | 5.8m / 6m / 12m |
| 24″ | 610.0 mm | 9.53 mm | 20.62 mm | 5.8m / 6m / 12m |
Note:
- Pipes are available in Seamless or Welded forms.
- Wall thickness can vary based on Schedule (SCH 10/40/80/160/XH/XXH).
- Custom sizes and lengths are available on request.
- All grades—P5, P9, P11, P22, and P91—are available in the sizes listed.
Global Reach of ASTM A335 P5, P9, P11, P22, P91 Pipes by Mcneil Instrument
- Middle East and North Africa (MENA): In MENA’s high-heat, high-pressure industrial settings, Mcneil’s ASTM A335 P-series pipes—particularly P5 and P22—are widely used in oil refineries, thermal power plants, and gas processing units. Their ability to withstand extreme temperatures and oxidative environments makes them ideal for long-term performance in desert and offshore applications.
- North America: Our ASTM A335 P91 and P11 alloy steel pipes are commonly deployed in supercritical boilers, chemical facilities, and industrial heating systems across North America. Fully compliant with ASME and ASTM specifications, these grades are trusted for their excellent creep resistance and mechanical strength under cyclic thermal loads.
- Europe: With stringent EN and PED standards in place, Europe relies on Mcneil’s A335 P9 and P22 pipes in nuclear power stations, pressure vessels, and heat recovery systems. Their durability and resistance to high-temperature corrosion make them essential in energy generation and advanced engineering applications.
- Asia-Pacific: The rapid industrial growth in Asia-Pacific creates robust demand for A335 P5 and P91 pipes, especially in petrochemical complexes, power infrastructure, and steam pipelines. Mcneil Instrument delivers consistent supply and quality, supporting critical operations in high-temperature and high-pressure environments.
- South America: From fertilizer plants to pulp and paper industries, our ASTM A335 P11 and P22 pipes are extensively used across South America. Their ability to resist thermal stress and corrosion in harsh conditions ensures long-term reliability in both industrial and energy applications.
Conclusion:
Choosing the right pipe grade is critical for system safety, efficiency, and longevity in high-temperature applications. With a proven track record, Mcneil Instrument stands as a trusted name in the manufacturing, supply, and export of ASTM A335 P5, P9, P11, P22, and P91 pipes across India and the globe.
Contact Mcneil Instrument today to get reliable, high-performance pipes tailored to your project needs.
