Gnee Steel stands as a dedicated supplier and proficient exporter, specializing in ASTM A387 / ASME SA387 GRADE 11 Class 1 alloy steel plates. With a steadfast commitment to excellence, Gnee Steel delivers top-quality products that align with industry standards, catering to diverse industrial applications.
ASTM A387 Grade 11 Class 1 is a chromium-molybdenum (Cr-Mo) alloy steel plate for pressure vessels and boilers needing high-temperature strength, creep resistance, and corrosion resistance, featuring about 1.25% chromium and 0.5% molybdenum, providing stability in harsh oil, gas, and petrochemical environments. The 'Class 1' denotes specific mechanical property requirements, differing from Class 2, with the material typically supplied normalized and tempered.
Key Characteristics
Alloy Content: Around 1.25% Chromium (Cr) and 0.5% Molybdenum (Mo).
Benefits: Excellent resistance to high temperatures, oxidation, and hydrogen attack, plus good creep resistance.
Applications: Ideal for welded boilers, pressure vessels, refineries, power plants, and petrochemical processing, especially where sour gas (H₂S) is present.
Heat Treatment: Requires proper heat treatment, often normalized and tempered, with a minimum tempering temperature of 1150°F (620°C) for stability.
Mechanical Properties: Meets specific tensile strength (e.g., 75-100 ksi) and yield strength (min 43 ksi) requirements, with Class 1 having different limits than Class 2.
In essence, it's a tough, heat-resistant steel plate designed for demanding elevated-temperature service in critical industries.
ASTM A387 Grade 11 Class1 Plate Specification :
Width: 1000mm-4500mm
Thickness: 5mm to 150mm
Length: 3000mm-18000mm
Supply Condition : As Rolled, Normalized Rolling, Furnace Normalizing, Vacuum Degassing, Simulated Post-Weld Heat Treatment or as per customer requirement.
Impact tested: -52° C
Process of Manufacturing: Hot-Rolled (HR)
Equivalents
| BS | EN | ASTM/ASME | DIN |
| 621 B | ––– | A387-11-1 | ––– |
Chromium & Molybdenum content
| Designation | Nominal Chromium Content (%) |
Nominal Molybdenum Content (%) |
| A387 Grade 11 | 1.25% | 0.50% |
Tensile Requirements for ASTM A387 Grade 11 Alloy Steel Plates Class 1 Plates
| Designation: | Requirement: | Grade 11 |
| A387 Grade 11 | Tensile strength, ksi [MPa] | 75 to 100 [515 to 690] |
| Yield strength, min, ksi [MPa]/(0.2% offset) | 43 [310] | |
| Elongation in 8 in. [200mm], min % | 18 | |
| Elongation in 2 in. [50mm], min, % | 22 | |
| Reduction of area, min % | ––– |
Chemical Requirements for ASTM A387 Grade 11 Alloy Steel Plates
| Element | Chemical Composition (%) | |
| A387 Grade 11 | ||
| Carbon: | Heat Analysis: | 0.05 - 0.17 |
| Product Analysis: | 0.04 - 0.17 | |
| Manganese: | Heat Analysis: | 0.40 - 0.65 |
| Product Analysis: | 0.35 - 0.73 | |
| Phosphorus: | Heat Analysis: | 0.035 |
| Product Analysis: | 0.035 | |
| Sulphur (max): | Heat Analysis: | 0.035 |
| Product Analysis: | 0.035 | |
| Silicon: | Heat Analysis: | 0.50 - 0.80 |
| Product Analysis: | 0.44 - 0.86 | |
| Chromium: | Heat Analysis: | 1.00 - 1.50 |
| Product Analysis: | 0.94 - 1.56 | |
| Molybdenum: | Heat Analysis: | 0.45 - 0.65 |
| Product Analysis: | 0.45 - 0.70 |
1What are the typical application fields of ASTM A387 Grade 11 Class1 ?
ASTM A387 Grade 11 Class 1 steel is primarily used in high-temperature environments for welded pressure vessels, boilers, and piping in the oil & gas, petrochemical, and power generation industries, prized for its excellent oxidation and corrosion resistance due to chromium and molybdenum content, making it ideal for handling hot liquids and gases in harsh conditions. It's also found in heat exchangers, chemical processing, and even some pharmaceutical applications.
2What is Common Testing Requirementsof ASTM A387 Grade 11 Class1 ?
Common testing for ASTM A387 Grade 11 Class 1 includes chemical analysis, tension tests (tensile strength, yield strength, elongation), and heat treatment verification, focusing on its ~1.25% Chromium and ~0.50% Molybdenum content for high-temperature pressure vessels, with mandatory normalizing & tempering (N&T) and potential Ultrasonic Testing (UT) or Charpy impact tests as agreed upon. Key mechanicals: Tensile 60-85 ksi, Yield min 35 ksi, Elongation min 19%
3What precautions should be taken when welding ASTM A387 Grade 11 Class1 material?
When welding ASTM A387 Grade 11 Class 1, use proper preheating (around 120-150°C) and control interpass temperatures (max ~315°C) to prevent hydrogen cracking due to its air-hardenable nature, select appropriate EB2 filler metals, ensure thorough cleaning, and always perform Post Weld Heat Treatment (PWHT) for stress relief, typically around 690°C for an optimal microstructure. A qualified Welding Procedure Specification (WPS) is essential to manage these critical steps, including proper joint preparation and fume control.
4What is ASTM A387 Grade 11 Class1 equivalent to?
ASTM A387 Grade 11 Class 1 is equivalent to ASME SA387 Grade 11 Class 1, sharing identical chemical makeup and mechanical properties, primarily used for high-temperature pressure vessels, with direct correspondence in ASME standards; while there's no exact DIN/EN match, BS 621 B is a British equivalent.
5What is the hardness of ASTM A387 Grade 11 Class 1?
ASTM A387 Grade 11 Class 1 steel typically has a Brinell hardness range of 150 to 180 HBW, although some sources mention a higher as-rolled hardness around 235 HBW before heat treatment, with its mechanical properties (like yield and tensile strength) defining its classification, not a specific hardness value for the final product. This chromium-molybdenum alloy is for high-temperature service, and while hardness is related, tensile/yield strength and elongation are key specifications.
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