What is ASME SA387 | Grade 11 Class 2 Equivalent to?
ASME SA387 Grade 11 Class 2 is equivalent to ASTM A387 Grade 11 Class 2, referring to the same chromium-molybdenum alloy steel for pressure vessels, differing only by the standard (ASME for boilers/pressure vessels, ASTM for materials) but sharing identical chemical composition and mechanical properties. In British standards, it's similar to BS 621B, while European (EN) and German (DIN) standards don't have direct single equivalents but relate to similar material designations.
ASME SA387 Grade 11 Class 2 (ASTM A387 Grade 11 CL2) is a high-performance chromium-molybdenum alloy steel plate intended for use in elevated temperature and high-pressure applications. As a pressure vessel grade steel, it is commonly associated with the construction of boilers, heat exchangers, and pressure vessels across the oil, gas, petrochemical, and power generation industries.
The material is defined by its specific chemical composition and enhanced mechanical properties:
Chemical Makeup: Nominal chrome content ranges from 1.00% to 1.50%, with molybdenum between 0.45% and 0.65%.
Corrosion Resistance: The higher levels of chromium provide excellent resistance to oxidation and corrosion, which is a critical requirement in sour gas applications.
Mechanical Strength: "Class 2" indicates higher mechanical properties than Class 1, offering an enhanced tensile strength range of 515–690 MPa (75–100 ksi).
SA387 Alloy Steel Plate is highly effective where liquids and gases are stored at higher temperatures due to its excellent thermal stability and weldability. Beyond Grade 11, the SA387 specification is available in various grades such as 12, 22, and 91 (available in Class 1 & 2) to meet different industrial demands. All plates are typically supplied with EN 10204 3.1/3.2 MTC (Mill Test Certificates) and can undergo optional testing-such as NACE, HIC, or UT (Ultrasonic Testing)-to ensure reliability in the most severe environments.
Chromium & Molybdenum content (according to the ASME specification):
| Designation | Nominal Chromium Content (%) | Nominal Molybdenum Content (%) |
|---|---|---|
| A387 Grade 11 | 1.25% | 0.50% |
Equivalents
| BS | EN | ASTM/ASME | DIN |
| 621 B | ––– | SA387-11-2 | ––– |
Tensile Requirements for Class 2 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 % |
Specifications for ASME SA387 Grade 11 Alloy Steel Plates
| Designation | Nominal Chromium Content (%) |
Nominal Molybdenum Content (%) |
| SA387 Grade 11 | 1.25% | 0.50% |
| Element | Melt Analysis (%) | Product Analysis (%) | Standard Limit |
| Carbon (C) | 0.05-0.17 | 0.04-0.18 | 0.17 max |
| Manganese (Mn) | 0.40-0.65 | 0.35-0.73 | 0.40-0.65 |
| Phosphorus (P) | ≤0.025 | ≤0.025 | 0.025 max |
| Sulfur (S) | ≤0.025 | ≤0..025 | 0.025 max |
| Silicon (Si) | 0.50-0.80 | 0.44-0.86 | 0.50-0.80 |
| Chromium (Cr) | 1.00-1.50 | 0.94-1.56 | 1.00-1.50 |
| Molybdenum (Mo) | 0.45-0.65 | 0.40-0.70 | 0.45-0.65 |
1 What is ASME SA387 Grade 11 Class 2 material?
ASME SA387 Grade 11 Class 2 is a chromium-molybdenum alloy steel plate for pressure vessels and boilers operating at elevated temperatures, offering excellent corrosion & oxidation resistance due to its ~1% Chromium and ~0.5% Molybdenum content, supplied normalized and tempered for enhanced strength, used in oil, gas, and petrochemical industries.
2What is the P number of SA 387 GR 11?
The ASME SA-387/ ASTM A387 Gr. 11 steel has the nominal composition of 1.25Cr-0.5Mo-Si with UNS designation number of K11789 and P number of 4.
3What are the primary advantages of ASME SA387 | Grade 11 material?
ASME SA387 Grade 11's primary advantages are its excellent performance in elevated temperature service, superior corrosion/oxidation resistance (especially in sour gas), enhanced tensile strength at high heat due to its Cr-Mo alloy, and good weldability, making it ideal for boilers, pressure vessels, and petrochemical equipment in demanding environments.
4What is the SA387 standard?
The ASME SA387 standard covers the supply of weldable chrome molybdenum alloy steel plates for pressure vessels used in elevated temperature service. The added molybdenum and chromium provides excellent corrosion resistance and high temperature resistance respectively.
5What is the difference between ASME SA387 | Grade 11 Class 2 and ASME SA387 | Grade 11 Class 1 ?ASME SA387 Grade 11 Class 1 and Class 2 share the same chemical composition (Cr-Mo alloy steel) but differ in their mechanical properties and required heat treatment, with Class 2 having higher tensile/yield strength and requiring a more stringent heat treatment (not just annealing), making it suitable for higher stress/temperature applications compared to Class 1. Class 2 offers better performance at elevated temperatures due to its enhanced properties.
6What is the chemical composition of ASME SA387 | Grade 11 Class 2 ?
ASME SA387 Grade 11 Class 2 is a chromium-molybdenum alloy steel for high-temperature pressure vessels, containing key elements like 1.00-1.50% Chromium (Cr) and 0.45-0.65% Molybdenum (Mo), plus controlled amounts of Carbon (C), Manganese (Mn), Silicon (Si), Phosphorus (P), and Sulfur (S) to provide strength and corrosion resistance at elevated temperatures. The Class 2 designation refers to mechanical properties (higher strength) rather than chemical differences, with Class 1 and 2 sharing the same composition.
7What are the typical application fields of ASME SA387 | Grade 11 Class 2 ?\
ASME SA387 Grade 11 Class 2 alloy steel is primarily used for high-temperature, high-pressure applications, especially in the oil, gas, and petrochemical industries, for fabricating equipment like pressure vessels, heat exchangers, boilers, and pipelines that handle hot liquids and gases, benefiting from its chromium and molybdenum content for excellent strength, corrosion, and oxidation resistance
8What is the weight of ASME SA387 | Grade 11 Class 2 ?
The weight of ASME SA387 Grade 11 Class 2 steel isn't a single number; it depends on the plate's dimensions (length, width, and thickness), but its density is around 7850 kg/m³ (0.283 lbs/in³), with a common example being 196 kg per square meter for a 25mm thick plate, allowing you to calculate weight based on area and thickness for any specific plate size.
9What precautions should be taken when welding ASME SA387 | Grade 11 Class 2 ?
When welding ASME SA387 Grade 11 Class 2 (a Cr-Mo alloy steel), key precautions involve mandatory preheating and post-weld heat treatment (PWHT) to prevent hydrogen cracking by reducing hardness and forming brittle martensite, using specific filler metals (like E8018-B2), maintaining strict interpass temperature control, and ensuring proper ventilation, PPE, and fire safety for personnel and the workspace
10What are Common Testing Requirements for ASME SA387 | Grade 11 Class 2 ?
For ASME SA387 Grade 11 Class 2, common testing includes Tensile Tests (strength, yield, elongation), Chemical Analysis, and typically Impact Tests (often optional but project-dependent), along with Radiographic Testing (RT), Hydrostatic/Pneumatic Testing, and Visual/NDT inspections for the finished vessel, ensuring mechanical integrity and specified chemical composition for high-temperature pressure vessels.
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