ASTM A335 P11 Seamless Pipes,ASME SA335 P11 Seamless Pipe,1.25Cr0.5Mo Pipe,1-1/4Cr1/2Mo Pipe
Chromium-Molybdenum Alloy Steel Pipes for High-Temperature & Pressure Service
ASTM A335 / ASME SA335 P11 seamless pipes are chromium-molybdenum (Cr-Mo) alloy steel pipes specifically designed for high-temperature and high-pressure applications. Manufactured in accordance with ASTM A335 and its ASME equivalent SA335, Grade P11 offers excellent creep resistance, oxidation resistance, and long-term mechanical stability, making it a proven material for boilers, superheaters, refineries, and power generation systems.
P11 seamless pipes are widely used in oil & gas, petrochemical, and thermal power industries where carbon steel pipes are no longer adequate.
What Is ASTM A335 ?
ASTM A335 (adopted by ASME as SA335) is the standard specification for seamless ferritic alloy-steel pipe intended for high-temperature service.
Download ASTM A335／A335M standard PDF
The most commonly used P grades in the power generation industry and petro-chemical plants are P11, P22 & P91.
ASTM A335 This specification covers seamless ferritic alloy-steel pipe for high-temperature service. The pipe shall be suitable for bending, flanging (vanstoning), and similar forming operations, and for fusion welding. Grade P2 and P12 steel pipes shall be made by coarse-grain melting practice. The steel material shall conform to chemical composition, tensile property, and hardness requirements. Each length of pipe shall be subjected to the hydrostatic test. Also, each pipe shall be examined by a non-destructive examination method in accordance to the required practices. The range of pipe sizes that may be examined by each method shall be subjected to the limitations in the scope of the respective practices. The different mechanical test requirements for pipes, namely, transverse or longitudinal tension test, flattening test, and hardness or bend test are presented.
Inspection and Test: Chemical Composition Inspection, Mechanical Properties Test(Tensile Strength,Yield Strength, Elongation, Flaring, Flattening, Bending, Hardness, Impact Test), Surface and Dimension Test,No-destructive Test, Hydrostatic Test.
Material Grade: P11 (1.25Cr-0.5Mo Alloy Steel)
ASTM A335 P11 is a 1.25% chromium – 0.5% molybdenum alloy steel that provides improved high-temperature strength and oxidation resistance compared to carbon steel grades.
1.ASTM A335 P11 Pipes Chemical Composition Requirement
| P11 Pipe Chemical Components (%) | ||||||||||||
| Grade | C | Mn | P | S | Si | Cr | Mo | V | Nb | N | Al | others |
| P11 | 0.05-0.15 | 0.30-0.60 | ≤0.025 | ≤0.025 | 0.50-1.00 | 1.0-1.50 | 0.44-0.65 | / | / | / | / | |
*C – Carbon, Mn – Manganese, P – Phosphorous, S – Sulfur, Si – Silicon, Cr-Chromium, Mo – Molybdenum.
ASME SA335 P11 Pipes Heat Treatment Requirements
| Grade | UNS Number | Heat Treat Type | Austenitizing/ Solutioning Temperature, min or range °F [°C] | Subcritical Annealing or Tempering Temperature, Min or range °F [°C] |
| P11 | K11597 | full or isothermal anneal normalize and temper | … | 1200[650] |
ASME SA335 P11 Pipes Tensile Requirements and Hardness:
| Mechanical properties | ||||
| Grade | Tensile | Yield | Elongation | Hardness |
| Strength (Mpa) | Strength (Mpa) | (%) | ||
| P11 | ≥415 | ≥220 | ≥30 | ≤89HRB |
- Flattening Test—One flattening test shall be made on specimens from each end of one finished tube, not the one used for the flaring test, from each lot.
- Flaring Test—One flaring test shall be made on specimens from each end of one finished tube, not the one used for the flattening test, from each lot.
- Hydrostatic or Nondestructive Electric Test—Each tube shall be subjected to the nondestructive electric test or the hydrostatic test. The type of test to be used shall be at the option of the manufacturer, unless otherwise specified in the purchase order.
Product Form & Manufacturing
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Product Type: Seamless alloy steel pipe
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Manufacturing Process: Hot finished / cold drawn
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Delivery Condition:
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Normalized
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Normalized & tempered (most common)
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Size Range & Specifications
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Outside Diameter: 1/8″ – 24″
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Wall Thickness: SCH 10 – SCH 160 / XXH
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Length: Random length or fixed length
(Custom sizes available on request)
Heat Treatment & Fabrication
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Pipes are typically supplied in normalized and tempered condition
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Preheating and post-weld heat treatment (PWHT) are recommended after welding
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Ensures improved toughness and long-term service stability
Testing & Inspection
ASTM A335 / ASME SA335 P11 pipes undergo comprehensive testing, including:
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Chemical analysis
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Tensile testing
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Flattening and bend tests
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Hydrostatic or NDT testing
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Dimensional inspection
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Visual inspection
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Certification: MTC / EN 10204 3.1
Applications of ASTM A335 P11 Seamless Pipes
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Boilers and superheaters
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High-temperature steam pipelines
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Oil & gas refineries
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Petrochemical processing units
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Power generation plants
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Pressure vessels and headers
ASTM A335 P11 vs P22 Pipes
| Item | P11 | P22 |
|---|---|---|
| Cr-Mo Content | 1.25Cr-0.5Mo | 2.25Cr-1Mo |
| Max Service Temp | ~540°C | ~580°C |
| Strength | Good | Higher |
| Typical Use | Boilers / refineries | Higher-temp service |
We are a professional A335 P11 Pipe, A335 P11 Seamless steel pipe supplier and exporter in China.A335 p11 is a typical Cr-Mo alloy steel pipe for high-temperature service and oil refinery applications.
P11 grade also known as 1.25Cr0.5Mo or 1-1/4Cr1/2Mo Grade
ASTM A335 P11 seamless pipe Specification.
1/4” Nominal to 24”O.D. Seamless Alloy Pipe Wall Thickness – Schedule 40 through XXH Length: Single Random Length, Double Random Length, 20 ft, 40 ft Ends Types: Plain, Beveled A335 Gr P11 seamless Pipe can be used as the starting material to produce A234 WP11 Pipe fittings,and match with A182 F11 flanges,and A182 F11 forged fittings.
A335 P11 pipes are used in power generation and in downstream oil ,as well as refinery application
How to order our ASTM A335 P11 Seamless Pipe/ASTM A335 P11 Pipes for oil refinery ?
Example#1
Type: ASTM A335 P11 Seamless Pipe.
Length: 6M.
Wall Thickness: SCH 80
Size: 8″
Ends: BE.
Material: ASTM A335 P11
MTC EN 10204 3.1 ,inspection and PMI pictures can be provided before shipment.
ASTM A335 P11 Alloy Steel Seamless Pipe
ASTM A335 Gr. P11 seamless pipes, with nominal chemical composition of “1.25Cr-0.5Mo” or “1.25Cr-0.5Mo-Si”, can be used for ASME B31.3 process piping. The ASME B31.3 Code has designated ASTM A335 Gr. P11 as a listed material and provided the basic allowable stresses in tension at various temperatures.
A335 P11 Pipe for High-Temperature and High-Pressure Service. P11 provides enhanced toughness, strength, hardness, and wear resistance often required in Power Plants, Space Craft, Nuclear Reactors, and Turbines.
Recommended Fittings:
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ASTM A234 WP11 Elbow (90° LR / SR, ASME B16.9)
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ASTM A234 WP11 Tee (Equal / Reducing)
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ASTM A234 WP11 Reducer (Concentric / Eccentric)
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ASTM A234 WP11 Pipe Cap
Recommended Flange Materials:
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ASTM A182 F11 Weld Neck Flange (ASME B16.5 / B16.47)
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ASTM A182 F11 Slip-On Flange
Alloy Steel Pipe Options
For higher temperature or pressure requirements:
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ASTM A335 P22 Seamless Pipe (2.25Cr-1Mo)
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ASTM A335 P91 Seamless Pipe (9Cr-1Mo-V)
- ASTM A335 P5 Seamless Pipe
