SA 387 Gr. 11 Cl. 2 is a chromium-molybdenum alloy steel designed for high-temperature pressure vessels.ASME SA 335 Gr. 11 CL 2 Alloy Steel Plates are suitable for bending, flanging, and similar forming operations, and for fusion welding. However, these products are tested rigorously by our highly qualified team using different techniques namely, transverse or longitudinal tension test, flattening test, and hardness or bend test etc.Furthermore, Alloy Steel Grade 11 CL 2 Plates has excellent features incorporate its rigidity, yield quality, weariness resistance, durability, and wear resistance. We offer them in different evaluations that meet the necessities of the customer. Contact us today to request free estimates!
SA387 Gr 11 CL 2 Steel Plate Chemical Composition
| C | Mn | P | S | Si | Cr | Mo |
| 0.04 - 0.17 | 0.35 - 0.73 | 0.035 | 0.035 | x 0.44 - 0.86 | 0.94 - 1.56 | 0.40 - 0.7 |
SA387 Grade 11 Class 2 Plate Mechanical Properties
| A387 / SA387 Grade 11 | Class 1 | Class 2 |
| Tensile Strength (ksi) | 60-85 | 70-90 |
| Tensile Strength (MPa) | 415-585 | 485-620 |
| Yield Strength (ksi) | 35 | 45 |
| Yield Strength (MPa) | 240 | 310 |
| Elongation in 50mm (%) | 19 | 18 |
| Elongation in 50mm (%) | 22 | 22 |
processing
SA 387 Grade 11 Class 2 is a 1.25Cr-0.5Mo heat-resistant alloy steel plate used for high-temperature and high-pressure pressure vessel applications. Its processing must comply with ASME SA-387/SA-387M to ensure excellent elevated-temperature strength, toughness, and resistance to hydrogen attack.
The typical processing sequence is as follows:
Melting
The steel is melted in an electric arc furnace (EAF), followed by ladle furnace (LF) refining and vacuum degassing (VD). This process reduces impurities such as sulfur and phosphorus, improves steel cleanliness, and ensures good weldability and toughness.
Casting
The refined molten steel is cast into ingots or continuous cast slabs. Strict control of pouring temperature and cooling rate helps prevent center segregation, shrinkage, and internal cracking.
Reheating
The slabs are reheated to approximately 1100–1200°C to achieve full austenitization, which is essential for subsequent rolling.
Hot Rolling
The slabs are rolled at high temperatures through multiple passes. The finishing temperature is carefully controlled to ensure a uniform, fine-grained microstructure and consistent mechanical properties across the plate thickness.
Normalization
The plates are heated to 890–940°C, held for a sufficient time, and then air-cooled. Normalization refines the grain structure, improves toughness, and enhances the uniformity of the material properties.
Tempering
Tempering is performed at 620–680°C, followed by slow cooling. This step relieves internal stresses, reduces hardness, and significantly improves impact toughness, which is critical for high-temperature service.
Straightening
After heat treatment, the plates are straightened to ensure flatness and dimensional accuracy.
Ultrasonic Testing (UT)
All plates undergo 100% ultrasonic inspection to detect internal defects such as laminations, porosity, or cracks.
Mechanical Testing
Tensile tests, impact tests (typically at 0°C or as specified), and hardness tests are conducted to verify that the material meets the required strength, ductility, and toughness levels.
Surface and Dimensional Inspection
The plates are inspected for surface defects such as cracks, seams, or indentations. Thickness, width, and length are also verified to meet customer and standard requirements.
Delivery
SA 387 Grade 11 Class 2 is normally supplied in the normalized and tempered (N+T) condition.
Key Applications
Oil & Gas:
Hydrogenation reactors, hydrocracking units, high-pressure vessels, separators, storage tanks, and equipment for sour gas service.
Petrochemical Industry:
Similar to oil & gas, for high-temperature processing and storage.
Power Generation:
Boiler drums, steam headers, furnace components, and heat exchangers in thermal power plants.
Chemical & Industrial:
General industrial equipment requiring high-temperature strength and corrosion resistance, like storage tanks and pressure vessels.
For more details about GNEE's steel products, contact us at beam@gneesteelgroup.com. We look forward to working with you.
How does SA 387 Grade 11 Class 2 differ from SA 387 Grade 11 Class 1?
SA 387 Grade 11 Class 2 has stricter requirements for toughness, lower impurity limits, and often more rigorous testing compared to Class 1. This makes Class 2 better suited for critical pressure vessel applications where resistance to brittle fracture is essential, while Class 1 is used in less demanding situations.
What types of pressure vessels use SA 387 Grade 11 Class 2?
It is used in a variety of pressure vessels, including boilers, heat exchangers, reactors, reformers, and hydrogenation units. It is particularly suitable for equipment operating at high temperatures and pressures where creep resistance and hydrogen attack resistance are essential.
In which industries is SA 387 Grade 11 Class 2 commonly used?
It is widely used in the oil and gas industry, petrochemical plants, chemical processing facilities, and power generation plants. It is also found in refineries, where it is used for equipment handling high-temperature hydrocarbons and hydrogen-rich fluids.
What are the key properties of SA 387 Grade 11 Class 2?
Key properties include excellent high-temperature strength, good creep resistance, high toughness, and resistance to hydrogen attack and sulfide corrosion. These properties make it suitable for use in boilers, heat exchangers, and pressure vessels operating under harsh conditions.
What is the difference between SA 387 Grade 11 Class 1 and Class 2?
Class 2 has stricter requirements for toughness, impurity control, and sometimes additional testing compared to Class 1. This makes Class 2 more suitable for critical applications where higher reliability and resistance to brittle fracture are required, such as in high-pressure or low-temperature service.
What is the difference in chemical composition between SA 387 Grade 11 Class 2 and SA 387 Grade 22?
SA 387 Grade 11 Class 2 is a 1.25Cr-0.5Mo steel, while Grade 22 is a 2.25Cr-1Mo alloy. The higher chromium and molybdenum content in Grade 22 provides better high-temperature strength and creep resistance, making it suitable for higher service temperatures than Grade 11 Class 2.
How does the maximum service temperature of SA 387 Grade 11 Class 2 compare to that of SA 387 Grade 91?
SA 387 Grade 11 Class 2 is typically used up to around 500°C, whereas SA 387 Grade 91 can operate at temperatures up to approximately 600°C or higher. Grade 91's higher chromium content and advanced heat treatment give it superior creep strength at elevated temperatures compared to Grade 11 Class 2.
What are the differences in mechanical properties between SA 387 Grade 11 Class 2 and carbon steel plates like SA 516 Grade 70?
SA 387 Grade 11 Class 2 has higher strength at elevated temperatures and better resistance to hydrogen attack than SA 516 Grade 70. While SA 516 Grade 70 is suitable for low-to-moderate temperature service, Grade 11 Class 2 is preferred for high-temperature pressure vessels due to its Cr-Mo alloying.
How does the weldability of SA 387 Grade 11 Class 2 compare to that of SA 387 Grade 22?
Both grades are weldable, but SA 387 Grade 11 Class 2 generally requires lower preheat and post-weld heat treatment (PWHT) temperatures than Grade 22. Grade 22's higher alloy content increases hardenability, making it more susceptible to cold cracking if proper welding procedures are not followed.