A335 P11 Chrome Moly Seamless Pipe
P11 alloy pipe is a chromium-molybdenum alloy steel pipe named according to the ASTM A335 P11 standard. It belongs to the category of special steels used in high-temperature and high-pressure environments. It has excellent high-temperature strength, oxidation resistance, and corrosion resistance, and is suitable for high-temperature pipeline systems in industries such as petroleum, chemical, and power.
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ASTM A335 P11 Chrome Moly Seamless Pipe is a seamless ferritic alloy steel pipe specifically designed for high-temperature and high-pressure service. Manufactured according to ASTM A335/ASME SA335, it contains approximately 1.00–1.50% Chromium (Cr) and 0.44–0.65% Molybdenum (Mo), with a minimum tensile strength of 415 MPa, minimum yield strength of 205 MPa, and minimum elongation of 30%. The chromium content improves oxidation and corrosion resistance, while molybdenum significantly enhances creep strength, thermal stability, and resistance to softening under prolonged elevated-temperature exposure.
As a result, P11 pipe offers superior high-temperature performance, pressure resistance, weldability, and service life compared with conventional carbon steel pipes. It is widely used in power plant steam lines, boiler systems, superheaters, petrochemical process piping, refinery units, heat exchangers, and other critical pressure-containing equipment operating under elevated temperatures and pressures.
GNEE supplies ASTM A335 P11 seamless alloy steel pipes for high-temperature and high-pressure service. Available with EN 10204 3.1/3.2 MTC, PMI testing, and third-party inspection.
ASTM A335 P11 seamless alloy steel pipes Specifications
| Item | Specification |
|---|---|
| Standard | ASTM A335/ASTM A335-M |
| Grade | P11 |
| Manufacturing Process | Seamless |
| Material Type | Chrome Moly Alloy Steel |
| Heat Treatment | Normalized & Tempered |
| Size Range | 1/2" – 24" |
| Wall Thickness | SCH 20 – SCH XXS |
| Length | Random / Fixed |
| End Type | Plain End / Bevel End / Threaded |
| Documentation | EN 10204 3.1 / 3.2 |
| Inspection | PMI, UT, Hydro Test |
| Third-Party Inspection | SGS, BV, TÜV, DNV |
| Available Stock | 3000 Tons |
| Lead Time | 20-35 days |
| MOQ | 30 Tons |
A335 P11 Cr-Mo alloy steel pipe for high-temperature service Chemical Composition:
| Element | ASTM A335 P11 (%) |
|---|---|
| Carbon | 0.05–0.15 |
| Manganese | 0.30–0.60 |
| Phosphorus | ≤0.025 |
| Sulfur | ≤0.025 |
| Silicon | 0.50–1.00 |
| Chromium | 1.00–1.50 |
| Molybdenum | 0.44–0.65 |
Chromium improves oxidation resistance while molybdenum enhances creep strength at elevated temperatures.
A335 P11 High Temperature Seamless Pipe Mechanical Properties:
| Property | Requirement |
|---|---|
| Tensile Strength | ≥415 MPa |
| Yield Strength | ≥205 MPa |
| Elongation | ≥30% |
ASTM A335 P11 Pipe Equivalent Materials
| Standard | Grade |
|---|---|
| ASTM A335 | P11 |
| ASTM A213 | T11 |
| ASTM A182 | F11 |
| EN 10216-2 | 13CrMo4-5 |
| DIN 17175 | 13CrMo44 |
| JIS G3462 | STBA20 |
Why choose GNEE ASTM A335 P11 seamless alloy steel pipes
ASTM A335 P11 pipes help reduce several key operational and project risks, including thermal fatigue, creep deformation, and oxidation-related failures. Its chrome-moly alloy composition helps reduce failures caused by thermal fatigue, creep deformation, oxidation, and pressure fluctuations, thereby extending maintenance intervals and lowering lifecycle costs. The material is suitable for bending, flanging, and fusion welding, making it easier to fabricate complex piping systems while maintaining structural integrity.
In EPC, refinery, and power generation projects, P11 pipe also helps procurement teams meet stringent engineering specifications and project approval requirements by supporting comprehensive quality documentation such as EN 10204 3.1/3.2 certificates, PMI reports, hydrostatic testing, and third-party inspections. This combination of reliability, durability, and compliance makes ASTM A335 P11 one of the most commonly specified alloy steel pipe grades for medium-to-high temperature industrial applications.
ASTM A335 P11 Hot Rolled Seamless Pipe – Size, Wall Thickness & Weight
| NPS | OD (mm) | SCH 10 WT | SCH 10 Weight (kg/m) | SCH 20 WT | SCH 20 Weight (kg/m) | SCH 40 WT | SCH 40 Weight (kg/m) | SCH 80 WT | SCH 80 Weight (kg/m) | SCH 160 WT | SCH 160 Weight (kg/m) |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1/2" | 21.3 | 2.11 | 0.61 | 2.77 | 0.81 | 3.91 | 1.13 | 6.02 | 1.70 | 7.92 | 2.23 |
| 3/4" | 26.7 | 2.31 | 0.81 | 2.87 | 1.01 | 3.91 | 1.37 | 6.35 | 2.10 | 9.27 | 2.78 |
| 1" | 33.4 | 2.77 | 1.14 | 3.38 | 1.37 | 4.55 | 1.84 | 6.35 | 2.53 | 9.53 | 3.41 |
| 1-1/4" | 42.2 | 2.87 | 1.56 | 3.56 | 1.93 | 4.85 | 2.62 | 6.35 | 3.37 | 9.53 | 4.54 |
| 1-1/2" | 48.3 | 3.02 | 1.91 | 3.68 | 2.25 | 5.08 | 3.08 | 7.14 | 4.34 | 11.13 | 5.55 |
| 2" | 60.3 | 3.05 | 2.60 | 3.91 | 3.25 | 5.54 | 4.62 | 8.74 | 7.17 | 12.70 | 10.45 |
| 2-1/2" | 73.0 | 3.91 | 3.72 | 5.16 | 5.00 | 7.01 | 6.80 | 9.53 | 9.25 | 12.70 | 12.50 |
| 3" | 88.9 | 3.91 | 4.64 | 5.49 | 6.58 | 7.62 | 9.02 | 11.13 | 13.70 | 15.09 | 18.42 |
| 4" | 114.3 | 4.19 | 6.36 | 6.02 | 9.00 | 8.56 | 13.0 | 13.49 | 20.5 | 19.05 | 30.1 |
| 6" | 168.3 | 4.78 | 10.1 | 7.11 | 15.2 | 10.97 | 24.0 | 18.26 | 38.0 | 25.40 | 52.5 |
| 8" | 219.1 | 5.16 | 15.0 | 8.18 | 23.0 | 12.70 | 36.2 | 23.01 | 64.8 | 31.75 | 91.2 |
| 10" | 273.0 | 5.49 | 21.2 | 9.27 | 32.4 | 15.09 | 50.0 | 28.58 | 92.3 | 38.10 | 130.0 |
| 12" | 323.9 | 5.97 | 28.1 | 10.31 | 42.3 | 17.48 | 65.0 | 33.32 | 119.0 | 44.45 | 165.0 |
| 14" | 355.6 | 6.35 | 33.6 | 11.13 | 51.0 | 19.05 | 77.5 | 35.71 | 140.0 | 50.80 | 200.0 |
| 16" | 406.4 | 6.35 | 39.0 | 12.70 | 61.0 | 21.44 | 92.5 | 40.49 | 170.0 | 57.15 | 245.0 |
| 18" | 457.0 | 7.11 | 48.0 | 14.27 | 76.0 | 23.83 | 110.0 | 45.24 | 210.0 | 63.50 | 300.0 |
| 20" | 508.0 | 7.11 | 54.0 | 15.09 | 87.0 | 26.19 | 130.0 | 50.01 | 250.0 | 69.85 | 360.0 |
| 24" | 609.6 | 8.18 | 77.0 | 17.48 | 115.0 | 30.96 | 175.0 | 59.54 | 330.0 | 82.55 | 450.0 |
ASTM A335 P11 pipe size tolerance
| ASTM A450 | Hot rolled | OD, mm | Tolerance |
|---|---|---|---|
| 101.6＜OD≤190.5 | +0.4/-1.2 | ||
| OD≤101.6 | +0.4/-0.8 | ||
| 190.5＜OD≤228.6 | +0.4/-1.6 | ||
| Cold Drawn | OD＜25.4 | ±0.10 | |
| 63.5≤OD＜76.2 | ±0.30 | ||
| 76.2≤OD≤101.6 | ±0.38 | ||
| 50.8≤OD＜63.5 | ±0.25 | ||
| 25.4≤OD≤38.1 | ±0.15 | ||
| 101.6＜OD≤190.5 | +0.38/-0.64 | ||
| 38.1＜OD＜50.8 | ±0.20 | ||
| 190.5＜OD≤228.6 | +0.38/-1.14 | ||
| ASTM A530/ASTM A335 | Nominal Pipe Size | 8＜OD≤12 | +2.38/-0.79 |
| 1/8≤OD≤1-1/2 | ±0.40 | ||
| 1-1/2＜OD≤4 | ±0.79 | ||
| 4＜OD≤8 | +1.59/-0.79 |
Heat Treatment of A335 P11 Chrome Moly Seamless Steel Pipe
Heat Treatment Purpose
ASTM A335 P11 is a chromium-molybdenum (Cr-Mo) alloy steel designed for high-temperature and high-pressure service. Heat treatment is critical because it directly affects:
Mechanical properties: tensile strength, yield strength, elongation
Creep resistance: long-term service at elevated temperatures
Toughness: resistance to cracking, especially at welds
Dimensional stability: minimizes distortion during fabrication
Improper or insufficient heat treatment is one of the most common causes of premature failure in P11 piping systems.
Heat Treatment Process
ASTM A335 P11 seamless pipes are typically supplied normalized and tempered, which involves two main steps:
Step 1: Normalizing
Temperature: 950–980°C (1742–1796°F)
Purpose:
Refines the grain structure
Relieves internal stresses from hot rolling
Improves uniformity of mechanical properties
Cooling: Air cooling (ambient)
Step 2: Tempering
Temperature: 700–720°C (1292–1328°F)
Purpose:
Enhances toughness
Reduces hardness to prevent brittleness
Improves creep resistance for elevated-temperature service
Cooling: Air cooling
Additional Considerations
Welded Components and PWHT
For welded P11 pipes or assemblies, Post-Weld Heat Treatment (PWHT) may be required:
Purpose:
Relieves residual stress from welding
Reduces risk of cracking at the weld zone
Ensures uniform mechanical properties across base metal and weld
Requirement: Determined by ASME Section I/ B31.1/ B31.3, wall thickness, and project specifications.
Heat Treatment Verification
International projects often require documentation for quality assurance:
Heat treatment records (furnace charts)
Batch traceability
Mechanical test reports (tensile, yield, elongation)
Optional hardness testing across pipe sections
ASTM A335 P11 Seamless Pipe Inspection & Testing
- Chemical Composition Analysis
- Tensile Test
- Flattening Test
- Hardness Test
- Hydrostatic Test
- Ultrasonic Examination (UT)
- Positive Material Identification (PMI)
- Dimensional Inspection
- Visual Inspection
ASTM A335 P11 Chrome Moly Seamless Steel Pipe Applications
| Application | Typical Use |
|---|---|
| Power Plants | Main steam piping, boiler piping, superheaters, reheaters |
| Oil Refineries | High-temperature process piping and transfer lines |
| Petrochemical Plants | Process piping for elevated-temperature fluids and gases |
| Industrial Boilers | Steam distribution systems and boiler headers |
| Heat Exchangers | High-temperature heat transfer systems |
| Pressure Vessels | Connecting piping for pressure equipment |
| EPC Projects | High-pressure and high-temperature piping systems |
A335 P11 Hot rolled seamless pipe MIT
A335 P11 High Pressure Steel Pipe factory
A335 P11 High-Temperature Alloy Steel Pipes packaging and shipping
FAQ
What is ASTM A335 P11 Pipe Used For?
ASTM A335 P11 is a chromium-molybdenum (Cr-Mo) seamless alloy steel pipe used for high-temperature and high-pressure service. It is commonly found in:
Power plant steam piping
Boiler and superheater systems
Oil refinery process piping
Petrochemical plants
Heat exchangers
Pressure vessel piping
P11 offers better heat resistance, creep strength, and service life than carbon steel pipes, making it suitable for long-term operation at elevated temperatures.
What Is the Difference Between P11 and P22?
| Property | P11 | P22 |
|---|---|---|
| Chromium (Cr) | 1.00–1.50% | 2.00–2.60% |
| Molybdenum (Mo) | 0.44–0.65% | 0.87–1.13% |
| High-Temperature Strength | Good | Better |
| Creep Resistance | Good | Higher |
| Service Temperature | Up to ~550°C | Up to ~600°C |
| Cost | Lower | Higher |
P22 contains more chromium and molybdenum than P11, providing better creep resistance and high-temperature performance. P11 is more economical for medium-temperature applications, while P22 is preferred for higher temperature and pressure systems.
What Is the Difference Between P11 and P91?
| Property | P11 | P91 |
|---|---|---|
| Chromium (Cr) | 1.00–1.50% | 8.00–9.50% |
| Molybdenum (Mo) | 0.44–0.65% | 0.85–1.05% |
| Yield Strength | ≥205 MPa | ≥415 MPa |
| High-Temperature Strength | Good | Excellent |
| Service Temperature | Up to ~550°C | Up to ~650°C |
| Cost | Lower | Much Higher |
P91 is a high-performance alloy steel developed for ultra-high-temperature and ultra-high-pressure applications. It provides significantly higher strength and creep resistance than P11 but requires stricter welding and heat treatment procedures and comes at a higher cost.
What Is the Difference Between P11 and ASTM A106 Grade B?
| Property | P11 | ASTM A106 Gr.B |
|---|---|---|
| Material Type | Alloy Steel | Carbon Steel |
| Chromium (Cr) | Yes | No |
| Molybdenum (Mo) | Yes | No |
| High-Temperature Performance | Excellent | Moderate |
| Creep Resistance | Yes | Limited |
| Service Life at High Temperature | Longer | Shorter |
| Cost | Higher | Lower |
ASTM A106 Grade B is a carbon steel pipe suitable for general-purpose pressure and temperature service. P11 contains chromium and molybdenum, providing superior high-temperature strength, oxidation resistance, and creep resistance. For steam systems, boilers, and refinery piping operating at elevated temperatures, P11 is the preferred choice.
What is the Pressure Rating of P11 Pipe?
The pressure rating of ASTM A335 P11 pipes depends on pipe size, wall thickness, and temperature according to ASME B31.1 / B31.3 codes.
For medium-temperature service (~550°C), standard schedule pipes (SCH 40–80) can handle pressures from 20 to 70 bar depending on diameter.
Exact rating must be calculated using design stress (S), OD, and wall thickness per applicable code.
Is P11 Suitable for Steam Service?
Yes. ASTM A335 P11 is commonly used for steam lines, superheaters, and boilers because it provides:
Excellent high-temperature strength
Good creep resistance for prolonged elevated-temperature service
Oxidation resistance due to chromium content
It is a preferred choice over carbon steel pipes (e.g., A106 Gr.B) for medium- to high-temperature steam systems.
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