What is the ASME SA387 Grade 11 Class 2 standard?
ASME SA387 Grade 11 Class 2 is a chromium-molybdenum alloy steel plate specification for high-temperature pressure vessels, offering enhanced strength and oxidation resistance, particularly for oil, gas, and petrochemical applications with sour gas, featuring about 1% Chromium and 0.5% Molybdenum for demanding elevated-temperature service.
ASME SA387 Grade 11 Class 2 (ASTM A387 Grade 11 CL2) is a specification for chromium-molybdenum alloy steel plates intended for use in elevated temperature applications, commonly associated with pressure vessels and heat exchangers. A pressure vessel grade steel for use in elevated temperature service, it is used in a variety of industries and is highly effective, particularly in the oil, gas and petrochemical industry, where liquids and gases are often stored at higher temperatures.
Nominal chrome content at 1.00% to 1.50%, and Moly 0.45% to 0.65% for SA387 GRADE 11 material.
The higher levels of chromium offer excellent resistance against corrosion and oxidation, which is essential in sour gas applications.
Key Characteristics:
Application:
Designed for elevated temperature service in welded boilers, pressure vessels, and heat exchangers (common in oil, gas, petrochemical industries).
Alloying Elements:
Contains about 1.25% Chromium (for oxidation/corrosion resistance) and 0.5% Molybdenum (for high-temp strength).
Class 2 Strength:
Specifies higher tensile strength (75-100 ksi or 515-690 MPa) and yield strength (min 43 ksi or 310 MPa) compared to Class 1.
Material:
Chromium-Molybdenum (Cr-Mo) Alloy Steel.
Benefits:
High-Temperature Performance: Maintains strength and integrity at elevated temperatures.
Corrosion Resistance: Chromium provides resistance to oxidation and corrosive environments, including "sour gas" (H₂S).
Weldability: Suitable for welding, essential for pressure vessel fabrication.
In Simple Terms: It's a tough, heat-resistant steel plate used to build things like large tanks and pipes that hold hot liquids or gases, ensuring they don't rust or break under pressure and heat.
Is ASME SA387 Grade 11 Class 2 carbon steel?
No, ASME SA387 Grade 11 Class 2 is not plain carbon steel; it's a chromium-molybdenum (Cr-Mo) alloy steel, a type of low-alloy steel specifically engineered for high-temperature pressure vessel applications, offering superior strength, oxidation, and corrosion resistance compared to carbon steel due to its added chromium and molybdenum content. While it has low carbon (around 0.04-0.17%), the alloying elements define it as a chromium-molybdenum steel, not a simple carbon steel.
What welding rod for ASME SA387 Grade 11 Class 2 carbon steel?
For ASME SA387 Grade 11 Class 2 (a 2.25% Cr-1% Mo low-alloy steel), you should use matching or equivalent 2.25Cr-1Mo welding consumables, such as AWS A5.28/A5.28M E80C-B2/ER80S-B2 for MIG/TIG or A5.5 E8018-B2 for SMAW (stick), ensuring proper preheat (around 149°C/300°F) and post-weld heat treatment (PWHT) for optimal mechanical properties, as this is a critical, code-specified material.
Is ASME SA387 Grade 11 Class 2 high speed steel?
No, ASME SA387 Grade 11 Class 2 is not high-speed steel (HSS); it's a low-alloy chromium-molybdenum (Cr-Mo) steel specifically for high-temperature pressure vessels, offering excellent oxidation resistance and strength, unlike HSS used for cutting tools that need extreme hardness and wear resistance at high speeds.
Equivalents
| BS | EN | ASTM/ASME | DIN |
| 621 B | ––– | SA387-11-2 | ––– |
| Designation | Nominal Chromium Content (%) | Nominal Molybdenum Content (%) |
|---|---|---|
| A387 Grade 11 | 1.25% | 0.50% |
Chemical Requirements for ASME SA387 Grade 11 Alloy Steel Plates
| Element | Chemical Composition (%) | |
| SA387 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 |
Tensile Requirements for Class 2 Plates
| Designation | Requirement | Grade 22 |
|---|---|---|
| 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. [200 mm], min % | 18 | |
| Elongation in 2 in. [50 mm], min, % | 22 | |
| Reduction of area, min % |
1What is ASME SA387 Grade 11 Class 2 material?
ASME SA387 Grade 11 Class 2 is a chromium-molybdenum (Cr-Mo) alloy steel plate designed for welded boilers and pressure vessels in high-temperature service, offering excellent oxidation/corrosion resistance and strength due to its ~1.25% Chromium and ~0.5% Molybdenum content, making it ideal for oil, gas, and petrochemical applications. It's typically supplied normalized and tempered, balancing high-temp performance with good formability and weldability for critical pressure-containing equipment.
2What is ASME SA387 Grade 11 Class 2 equivalent to?
ASME SA387 Grade 11 Class 2 is essentially the same as ASTM A387 Grade 11 Class 2, used interchangeably for Cr-Mo alloy steel in pressure vessels, with the key difference being the standard (ASME for boilers/pressure vessels, ASTM for general materials). Internationally, its closest equivalent is the British Standard BS 621B, while the European equivalent is EN 10028 13CrMoSi5-5, though not a direct match in all properties.
3What is the hardness of ASME SA387 Grade 11 Class 2 ?
ASME SA387 Grade 11 Class 2 doesn't have a single fixed hardness value but must meet minimum tensile properties, typically requiring a minimum yield strength of 310 MPa (45 ksi) and tensile strength between 515-690 MPa (75-100 ksi), with hardness varying based on thickness and heat treatment, but generally falling within Brinell ranges suitable for these strength levels, often around 130-170 HBW (Brinell hardness) for typical applications, though specific hardness testing (like Brinell, Rockwell) is required per project.
4What temperature is ASME SA387 Grade 11 Class 2 ?
ASME SA387 Grade 11 Class 2 is a high-temperature alloy steel for pressure vessels, with its heat treatment requiring a minimum tempering temperature of 620°C (1150°F), and it's designed for service in elevated temperatures, often used in ranges like 350°C to 480°C (around 660°F to 900°F), offering good corrosion resistance in oil/gas applications.
5What are the typical application fields of ASME SA387 Grade 11 Class 2 ?
ASME SA387 Grade 11 Class 2 is primarily used for pressure vessels and boilers in high-temperature applications, especially within the oil, gas, and petrochemical industries, due to its chromium-molybdenum alloy composition offering excellent high-temperature strength, corrosion, and oxidation resistance. Key applications include heat exchangers, pipelines, storage tanks, flanges, and other processing equipment handling hot liquids and gases, even in sour (sulfidic) environments.
6What precautions should be taken when welding ASME SA387 Grade 11 Class 2 ?
When welding SA387 Grade 11 Class 2 (a Cr-Mo alloy steel), key precautions involve mandatory preheating (around 149°C/300°F), appropriate filler metal (EB2 group), strict adherence to WPS/PQR, and Post-Weld Heat Treatment (PWHT) (around 690°C/1275°F) to prevent brittle martensitic phase formation and cracking, alongside standard safety (PPE, ventilation, fire watch).
7What is the P number of ASME SA387 Grade 11 Class 2 ?
Based on the ASME Boiler and Pressure Vessel Code (BPVC) Section IX, the P-number for ASME SA387 Grade 11 Class 2 is P-No. 4.
If you want to learn more about ASME SA387 Grade 11 Class 2 GNEE's products, you can send an email to info@gneesteels.com . We are more than happy to assist you.
