ASTM A335/A335M pipe specification

ASTM A335/A335M, also referred to as ASME SA-335/SA-335M, is the internationally recognized specification for seamless ferritic alloy steel pipes intended for high-temperature service. These alloy steel pipes are engineered for extreme temperature and pressure conditions, making them ideal for use in power plants, petrochemical industries, refineries, and industrial boilers.

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Key Applications of ASTM A335 Alloy Steel Pipes

ASTM A335 seamless alloy steel pipes are widely used in:

Power generation: Superheaters, reheaters, and main steam lines in supercritical and ultra-supercritical boilers (P91, P92).

Petrochemical & oil refining: Cracking furnace tubes and high-temperature reactors (P11, P22).

Natural gas industry: High-temperature gas transport pipelines.

Aerospace & nuclear sectors: High-performance heat-resistant piping solutions.

Material Grades Covered

The ASTM A335/A335M specification includes several grades of ferritic alloy steel, each tailored for specific thermal and mechanical performance:

Common Grades: P1, P2, P5, P9, P11, P22, P91

Advanced Grades: P23, P36, P92

Each grade offers unique properties in terms of high-temperature strength, creep resistance, and oxidation resistance.

Example: ASTM A335 P91 pipe exhibits nearly double the high-temperature strength of conventional steels at 550°C.

Standard Dimensions and Customization

Outer Diameter: 21.3mm – 762mm

Wall Thickness: 2.0mm – 130mm

Length: Standard 6m or 12m; custom lengths available

Special sizes: Available upon request, e.g., 711mm × 25mm thick-walled pipes

Manufacturing and Heat Treatment

ASTM A335 pipes are produced through methods such as:

Hot rolling

Cold drawing

Hot expansion

Heat treatment, such as normalizing and tempering, is essential to ensure pipe durability and temperature resistance (e.g., P91: 1040°C normalize + 730°C temper).

Testing and Quality Control

Each ASTM A335 pipe undergoes rigorous testing to meet quality standards:

Non-Destructive Testing (NDT): Ultrasonic (UT), Radiographic (RT)

Hydrostatic Pressure Testing

Optional Tests: Grain size analysis, hardness testing, and chemical composition verification

Comparison with Other Pipe Standards

Common Specifications:

Non-standard specifications: Some manufacturers can customize special sizes, such as large-diameter thick-walled pipes (such as 711×25mm).
Length: Usually 6m, 12m fixed length, can also be customized according to customer needs. A high-temperature piping system that can meet different size requirements.

2. Material and brand
ASTM A335/A335M standard covers a variety of ferritic alloy steel materials (low/medium alloy steel with chromium content ≤10%), such as P1, P2, P5, P5B, P5C, P9, P11, P12, P21, P22, P23, P36, P91 (Type1, Type2), P92, etc.

3. Chemical composition
ASTM A335 contains multiple grades, and the content of chromium (Cr) and molybdenum (Mo) of different grades determines its temperature resistance and corrosion resistance.

Note: High alloy grades such as P91/P92 have stronger creep resistance and oxidation resistance due to the presence of tungsten (W), boron (B) and other elements.

4. Mechanical performance requirements

Ordering Guidelines for ASTM A335 Pipes

When ordering ASTM A335 seamless alloy steel pipes, be sure to specify:

Material grade (e.g., P22, P91)

Size and length

Delivery condition (heat treatment method)

End finishing (plain, beveled, threaded)

Required tests (e.g., NDT, mechanical tests)

Applicable standards and supplementary requirements

Latest Revision: ASTM A335/A335M-24b

The ASTM A335/A335M-24b version, released in October 2024, introduced updates including:

Inclusion of new grades like P92

Optimized alloying elements for enhanced performance at up to 625°C

Enhanced compliance with global codes such as ASME using dual SI/Imperial units

Why Choose ASTM A335 Seamless Pipes?

Exceptional heat and pressure resistance

Proven creep and corrosion performance

Extensive material grade options for specific environments

Reliable mechanical strength and long service life

Conclusion

ASTM A335/A335M alloy steel pipes are essential for high-stress, high-temperature environments across industries. With superior thermal stability, mechanical strength, and oxidation resistance, these seamless pipes—especially grades like P91 and P92—are the top choice for demanding applications in power plants, refineries, and high-performance piping systems.

For reliable supply of ASTM A335 P5, P9, P11, P22, P91 pipes, choose manufacturers with strict quality control and full certification compliance.