Introduction

ASTM A335 P91 alloy steel pipe is renowned for its superior high-temperature strength and creep resistance, making it a preferred choice for ultra-supercritical boilers, petrochemical plants, and heavy-duty power-generation equipment. Its high chromium and molybdenum content offers outstanding service life under extreme pressures and temperatures.

Mcneil Instrument is a leading manufacturer, supplier, and exporter of ASTM A335 P91 alloy steel pipes in India. With advanced production facilities and a global-quality focus, Mcneil ensures reliable supply for critical applications both domestically and in international arenas.

Key Properties of P91 Alloy Steel

  • Chromium (8.00–9.50%) and Molybdenum (0.85–1.05%) significantly enhance strength and oxidation resistance.
  • Vanadium, Niobium, and Nitrogen form stable carbides and nitrides, refining grain structure and boosting creep resistance.
  • Mechanical Profile: Tensile strength ≥ 585 MPa; yield strength ≥ 415 MPa; elongation ≥ 20%.

Manufacturing & Quality Assurance

  1. Raw Material: High-grade P91 alloy billets.
  2. Pipe Forming: Hot-rolled seamless production.
  3. Heat Treatment: Normalizing at ~1060 °C plus tempering at ~760 °C to ensure optimal microstructure.
  4. Testing Protocols:
    • Chemical composition checks.
    • Mechanical tests: tensile, hardness.
    • Hydrostatic testing for pressure integrity.
    • NDT: Ultrasonic or radiography.
    • Positive Material Identification (PMI).
  5. Certifications & Traceability: Mill Test Certificates (EN 10204), ASME SA335, IBR approval, and optional NACE compliance for sour-service use.

Technical Specifications & Mechanical Properties of ASTM A335 P91 Alloy Steel Pipe

SpecificationDetails
StandardASTM A335 / ASME SA335
GradeP91
UNS DesignationK91560
Manufacturing ProcessSeamless, hot-finished or cold-drawn
TypeFerritic alloy steel
ApplicationHigh-temperature service (boilers, power plants)
End TypesPlain End, Beveled End, Threaded End
Heat TreatmentNormalized, Tempered

Mechanical Properties of ASTM A335 P91 Pipe

PropertyValue
Tensile Strength≥ 585 MPa (85 ksi)
Yield Strength≥ 415 MPa (60 ksi)
Elongation≥ 20%
Hardness≤ 250 HB / 24 HRC
Impact ToughnessExcellent at elevated temperatures

ASTM A335 P91 Dimensions & Wall Thickness Chart

Nominal Pipe Size (NPS)Outside Diameter (OD in mm)Wall Thickness Range (mm)
½″21.32.77 to 8.13
1″33.43.38 to 10.97
2″60.33.91 to 15.88
4″114.36.02 to 21.44
6″168.37.11 to 28.58
8″219.18.18 to 33.32
10″273.09.27 to 38.89
12″323.89.53 to 44.45
14″ and aboveAs per requestCustomizable

Certifications for ASTM A335 P91 Alloy Steel Pipe

Certification TypeDescription
ASTM / ASME ComplianceASTM A335, ASME SA335
IBR CertificationIndian Boiler Regulation Approved
EN 10204 3.1 / 3.2Mill Test Certificates with third-party inspections
NACE MR0175 / MR0103For sour service (if required)
PED (Pressure Equipment Directive)For EU pressure equipment applications
ISO 9001:2015Quality Management System Certification

Available Sizes & Specifications of ASTM A335 P91 Pipes

ParameterAvailable Options
Nominal Pipe Size (NPS)½″ to 24″ NB
Outside Diameter (OD)21.3 mm to 610 mm
Wall ThicknessSCH 20 to SCH XXS (and custom on request)
LengthsSingle Random, Double Random, Cut Lengths
End TypesBeveled End (BE), Plain End (PE), Threaded (TE)
Surface FinishBare, Painted, Varnished, Oiled
Delivery ConditionHeat-treated (Normalized + Tempered)

Global Reach of Mcneil Instrument: P91 Alloy Steel Pipes

  • In Saudi Arabia, Mcneil Instrument is a reliable manufacturer of P91 alloy steel pipes, supporting high-efficiency power plants.
  • In Qatar, we excel as an exporter, supplying P91 pipes for large petrochemical and energy installations.
  • Industries in Nigeria benefit from our role as a supplier, relying on P91 pipes for thermal power and industrial boilers.
  • As an exporter in Ghana, Mcneil provides pipes tailored for steam and heat-transfer systems.
  • In Texas, Mcneil is a respected manufacturer and supplier, delivering P91 pipes for ultra-supercritical boilers and refinery systems.
  • From Chicago, we act as a dependable exporter, meeting stringent ASME and ASTM requirements.
  • In Malaysia, we serve as a trusted supplier and exporter, offering P91 pipes for power and petrochemical industries.
  • In Singapore, Mcneil is known as a high-quality manufacturer and exporter, delivering pipes for offshore energy modules.
  • Across Brazil, we are a strong supplier, providing P91 pipes to heavy-duty power and refining projects.

Conclusion

P91 alloy steel pipes are essential for high-temperature, high-pressure industrial environments. With Mcneil Instrument as your manufacturer, supplier, and exporter, you can ensure superior reliability, full certification, and comprehensive global support