ASTM A335 Grade 1¼Cr-½Mo P11 Alloy Steel Seamless Pipe for API Standard 560 Fired Heater

Brand Name:YUHONG
Certification:ABS, GL, DNV, NK, PED, AD2000, GOST9941-81, CCS, ISO 9001-2008
Model Number:P11, 1 1/4Cr-1/2Mo
Minimum Order Quantity:1000KG
Delivery Time:30 days
Payment Terms:T/T, L/C at sight
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Location: Ningbo Zhejiang China
Address: 20TH FLOOR,NO.1 NEW WORLD BUILDING ,NO.1018 MINAN ROAD,YINZHOU DISTRICT, NINGBO CITY, ZHEJIANG PROVINCE, CHINA
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ASTM A335 Grade 1¼Cr-½Mo P11 Alloy Steel Seamless Pipe for API Standard 560 Fired Heater


ASTM A335 Grade P11 (1¼Cr-½Mo) seamless pipes deliver exceptional high-temperature creep resistance and oxidation stability in fired heaters. Engineered for API 560 compliance, these pipes ensure reliable performance in radiant/convection sections up to 550°C. Ideal for hydrocarbon processing, they combine weldability, stress tolerance, and cost efficiency for critical heater tube service.


Chemical Composition of ASTM A335 Grade P11 (1¼Cr-½Mo)​

ElementComposition (% Weight)
Carbon (C)0.05–0.15
Manganese (Mn)0.30–0.60
Phosphorus (P)≤ 0.025
Sulfur (S)≤ 0.025
Silicon (Si)0.50–1.00
Chromium (Cr)1.00–1.50
Molybdenum (Mo)0.44–0.65
​​Notes​​Residuals (Cu, Ni, etc.) ≤ 0.50% combined

Mechanical Properties of ASTM A335 P11​

PropertyValue
​​Tensile Strength​​≥ 415 MPa (60 ksi)
​​Yield Strength​​≥ 205 MPa (30 ksi)
​​Elongation (50mm Gauge)​​≥ 30% (varies with wall thickness)
​​Hardness (Max)​​197 HBW / 207 HV
​​Impact Test​​Charpy V-notch ≥ 20J @ 20°C (Optional per spec)
​​Notes​​Properties apply after heat treatment (normalize + temper)

Equivalent Grades of P11 Across Standards​

StandardGrade DesignationUNS NumberCommon Name
​​ASTM/ASME​​A335 Gr. P11K115971¼Cr-½Mo
​​EN​​13CrMo4-51.733513CrMo4-5
​​ISO​​CrMo 1 1/4 1/2--
​​JIS​​STPA 25-Chrome-Moly Pipe
​​Notes​​UNS K11597 is the universal cross-standard identifier

Common Alloy Tubes in Fired Heaters​

Alloy GradeCommon DesignationTypical Use in Fired HeatersWhy Used
​​Carbon Steel​​A106 Gr.B / A53Low-temp sections, economizersCost-effective for ≤ 425°C
​​1¼Cr-½Mo​​ASTM A335 P11Radiant/Convection sections (≤ 550°C)Creep resistance, weldability
​​2¼Cr-1Mo​​ASTM A335 P22High-temp radiant sections (≤ 575°C)Better creep strength than P11
​​9Cr-1Mo​​ASTM A335 P9Superheaters (≤ 650°C)Oxidation resistance
​​Alloy 800H/HT​​UNS N08810/11High-temp crackers (≤ 900°C)Carburization/oxidation resistance

Radiant Section Components in Fired Heaters​

ComponentFunction
​​Radiant Tubes​​Contain process fluid; absorb direct flame radiation
​​Burners​​Generate flames to heat tubes
​​Refractory Lining​​Insulates walls/floor, reflects heat toward tubes
​​Tube Supports​​Hold tubes in position (e.g., guides, hangers)
​​Shock/Sight Doors​​Allow visual inspection and emergency access
​​Header Pipes​​Distribute fluid to/from tube banks
​​Crossover Piping​​Connect radiant/convection sections
​​Steel Casing​​Structural enclosure containing insulation
​​Stack/Damper​​Flue gas exit path with draft control (connects to convection section)

For API 560 fired heaters, ASTM A335 P11 seamless pipes provide a proven solution for demanding radiant/convection environments. Their balanced chromium-molybdenum chemistry offers superior strength, thermal stability, and corrosion resistance. Optimized for longevity and safety in refineries/petrochemical units, P11 pipes are a cost-effective choice for sustained high-temp operation.


China ASTM A335 Grade 1¼Cr-½Mo P11 Alloy Steel Seamless Pipe for API Standard 560 Fired Heater supplier

ASTM A335 Grade 1¼Cr-½Mo P11 Alloy Steel Seamless Pipe for API Standard 560 Fired Heater

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