What is ASTM A387 Grade 11 Class 1equivalent to?
ASTM A387 Grade 11 Class 1 is a chromium-molybdenum alloy steel for high-temperature pressure vessels, with key equivalents including ASME SA-387 Gr 11 Cl 1, and corresponding international standards like BS 621B (though less common now), offering specific tensile strength (415-585 MPa) and 1.25% Chromium / 0.5% Molybdenum content for applications needing good oxidation/corrosion resistance, such as in petrochemical reactors.
ASTM A387 Grade 11 Class 1 is a chromium-molybdenum (Cr-Mo) alloy steel plate specifically engineered for welded boilers and high-temperature pressure vessels. Often referred to in the industry as "1.25 Chrome 0.5 Moly," its nominal chemical profile consists of 1.25% Chromium and 0.5% Molybdenum. This precise composition provides the foundation for the steel's ability to resist oxidation and maintain structural stability under prolonged thermal stress.
The strategic employment of these plates is evident within the oil and gas sectors, the petrochemical industry, and power generation. In contexts where gases and liquids endure elevated temperatures-such as in hydrogenation reactors, synthesis towers, and boiler systems-this material emerges as a steadfast solution. Chromium provides essential resistance to oxidation and corrosion by forming a protective stable oxide layer, while Molybdenum enhances "creep strength," allowing the metal to resist permanent deformation under high mechanical stress at heat.
Key Characteristics:
Material Type: Chromium-Molybdenum (Cr-Mo) Alloy Steel Plate.
Primary Use: Welded boilers and pressure vessels for elevated temperature service.
Key Alloying Elements: 1.00%–1.50% Chromium (Cr) and 0.45%–0.65% Molybdenum (Mo).
Performance: Excellent high-temperature strength, creep resistance, and resistance to hydrogen corrosion (HTHA).
Class 1 vs. Class 2: Class 1 is characterized by a lower tensile strength range (60–85 ksi / 415–585 MPa) compared to Class 2. This lower strength profile translates into superior ductility and workability, making it ideal for components requiring significant forming.
Processing: Typically supplied in the normalized or annealed condition to ensure a refined grain structure.
By maintaining a controlled carbon equivalent and utilizing modern refining techniques like vacuum degassing, this grade ensures high cleanliness levels. This is crucial for preventing temper embrittlement and ensuring the longevity of critical equipment in hot, high-pressure environments.
SA387 GR 11 CLASS 1 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)
What is the hardness of ASTM A387 Grade 11 Class 1 steel?
ASTM A387 Grade 11 Class 1 steel typically has a Brinell hardness range of 143 to 217 HB, although it's primarily specified by its tensile properties (60-85 ksi tensile, 35 ksi yield) for high-temperature pressure vessel service, with Class 1 having lower strength but better elongation than Class 2.
What is ASTM A387 Grade 11 Class 1 high speed steel?
ASTM A387 Grade 11 Class 1 is a Chromium-Molybdenum (Cr-Mo) alloy steel plate designed for welded boilers and pressure vessels used at elevated temperatures, offering good strength and excellent corrosion/oxidation resistance, particularly in oil, gas, and petrochemical industries, with Class 1 denoting specific mechanical properties and purity standards higher than Class 2. It contains about 1.0-1.5% Chromium and 0.45-0.65% Molybdenum, making it suitable for high-temperature service (around 350-480°C) in hydrogenation reactors and synthesis towers.
10 What precautions should be taken when welding ASTM A387 Grade 11 Class 1?
When welding ASTM A387 Grade 11 Class 1, prioritize low-hydrogen consumables (like E8018-B2), ensure thorough joint cleaning, apply preheat (minimum 250°F/121°C) to prevent cracking, control interpass temperature, and implement slow, controlled cooling post-weld, along with standard welding safety (PPE, ventilation) for this high-strength, high-temperature alloy used in pressure vessels.
Equivalents
| BS | EN | ASTM/ASME | DIN |
| 621 B | ––– | A387-11-1 | ––– |
Dimension Range SA 387 GR. 11 CL. 1 Alloy Steel
| Grade | Product type | Thickness in |
Width | Length in |
|---|---|---|---|---|
| Grade 11 | Plate | 0.185 - 3.60 4.70 - 91.4 |
60 - 131.9 1500 - 3350 |
73 - 590 1900 - 15000 |
Chemical Requirements
| Element Composition % | ||
|---|---|---|
| SA 387 Grade 11 |
SA 387 Grade 22 |
|
| Carbon, max: | ||
| Heat analysis | 0.05-0.17 | 0.05-0.15A |
| Product analysis | 0.04-0.17 | 0.04-0.15A |
| Manganese, max: | ||
| Heat analysis | 0.40-0.65 | 0.30-0.60 |
| Product analysis | 0.35-0.73 | 0.25-0.66 |
| Phosphorus, max: | ||
| Heat analysis | 0.025 | 0.025 |
| Product analysis | 0.025 | 0.025 |
| Sulfur, max: | ||
| Heat analysis | 0.025 | 0.025 |
| Product analysis | 0.025 | 0.025 |
| Silicon: | ||
| Heat analysis | 0.50-0.80 | 0.50 max |
| Product analysis | 0.44-0.86 | 0.50 max |
| Chromium: | ||
| Heat analysis | 1.00-1.50 | 2.00-2.50 |
| Product analysis | 0.94-1.56 | 1.88-2.62 |
| Molybdenum: | ||
| Heat analysis | 0.45-0.65 | 0.90-1.10 |
| Product analysis | 0.40-0.70 | 0.85-1.15 |
Tensile Requirements For Class 1 Plates
| SA 387 Grade 11 |
SA 387 Grade 22 |
|
|---|---|---|
| Tensile strength, ksi [MPa] | 60 to 85 [415 to 585] |
60 to 85 [415 to 585] |
| Yield strength min. ksi [MPa] | 35 | 30 |
| Elongation in 8 in. [200 mm], min. % | 19 | |
| Elongation in 2 in. [50 mm], min. % | 22 | 18 |
| Reduction of area, min % | 45 40 |
1 What temperature is ASTM A387 Grade 11 Class 1?
ASTM A387 Grade 11 Class 1 is a chromium-molybdenum steel for high-temperature service, often used in the range of 316°C to 593°C (600°F to 1100°F), with specific maximum use temperatures depending on the ASME code, such as around 649°C (1200°F) for some applications, but its minimum tempering temperature is typically 1150°F (620°C) for heat treatment to achieve desired toughness for elevated temperature use.
2 What welding rod for ASTM A387 Grade 11 Class 1 ?
For ASTM A387 Grade 11 Class 1 (1.25Cr-0.5Mo alloy steel), use low-hydrogen, chromium-molybdenum matched electrodes like E7018-B2L (SMAW/stick) or E71T1-B2L (FCAW), or for higher strength, consider E8018-B3 or matching ER80S-B3 (GTAW/MIG) filler wires, always ensuring proper preheat (around 149°C/300°F) and post-weld heat treatment (PWHT) for elevated temperature service.
3 What is the P number of ASTM A387 Grade 11 Class 1?
The P-number for ASTM A387 Grade 11, which is a chromium-molybdenum alloy steel (1.25Cr-0.5Mo), is P Number 4, a classification used in welding codes like ASME for grouping similar materials for welding procedures, despite variations in phosphorus content between Class 1 and Class 2.
4 What is ASTM A387 Grade 11 Class 1 equivalent to?
ASTM A387 Grade 11 Class 1 is a chromium-molybdenum alloy steel for high-temperature pressure vessels, equivalent to ASME SA387 Grade 11 Class 1 (its ASME counterpart) and also comparable to European standards like BS 621B and EN 10CrMo910, offering similar properties for global projects.
5 Is ASTM A387 Grade 11 Class 1 carbon steel?
No, ASTM A387 Grade 11 Class 1 is alloy steel, not plain carbon steel, specifically a chromium-molybdenum (Cr-Mo) steel designed for high-temperature pressure vessels, featuring significant chromium (around 1.25%) and molybdenum (around 0.5%) for enhanced oxidation and corrosion resistance, making it superior to basic carbon steels for demanding applications like boilers and reactors.
6 What are the typical application fields of ASTM A387 Grade 11 Class 1?
ASTM A387 Grade 11 Class 1 steel is primarily used for welded pressure vessels and boilers in high-temperature service, especially in the oil, gas, and petrochemical industries, due to its excellent chromium-molybdenum alloy properties offering superior heat and corrosion resistance for transporting hot liquids and gases. Key applications include heat exchangers, flanges, piping, and high-temperature ducting where strength and resistance to oxidation are critical.
7 What is the composition of ASTM A387 Grade 11 Class 1 ?
ASTM A387 Grade 11 Class 1 is a chromium-molybdenum alloy steel for high-temperature pressure vessels, containing approximately 1.00-1.50% Chromium (Cr), 0.45-0.65% Molybdenum (Mo), and balanced amounts of Carbon, Manganese, Silicon, Phosphorus, and Sulfur, offering enhanced creep and oxidation resistance compared to carbon steels, with Class 1 indicating the lower tensile strength range.
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