Which standard covers SA 387 Grade 11 Class 2?

SA 387 Grade 11 Class 2 is a chromium-molybdenum alloy steel plate specified in the ASME SA-387/SA-387M standard, primarily used for pressure vessels and boilers operating at elevated temperatures, where it provides good strength retention, creep resistance, and resistance to hydrogen attack and other high-temperature degradation mechanisms.

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!

Equivalents

Specifications for ASME SA387 Grade 11 Alloy Steel Plates

Tensile Requirements for ASME SA387 Grade 11 Alloy Steel Plates Class 2 Plates

Chemical Requirements for ASME SA387 Grade 11 Alloy Steel Plates

SA 387 Grade 11 Class 2 is a 1.25Cr-0.5Mo heat-resistant alloy steel plate used primarily in high-temperature, high-pressure pressure vessel applications. Its production process must comply with the ASME SA-387/SA-387M standard to ensure excellent elevated-temperature strength, toughness, and resistance to hydrogen attack.

The typical manufacturing process is as follows:

Melting

The steel is melted in an electric arc furnace (EAF) and refined using ladle furnace (LF) and vacuum degassing (VD) processes. This ensures low levels of sulfur, phosphorus, and other impurities, resulting in high steel cleanliness, good toughness, and excellent weldability.

Ingot Casting or Continuous Casting

After refining, the molten steel is cast into ingots or continuous cast slabs. Strict control of pouring temperature and cooling rate helps prevent center segregation and internal cracks.

Heating and Rolling

The slabs are reheated to approximately 1100–1200°C and then rolled in multiple passes. Controlled reduction and finishing temperatures ensure a uniform, fine-grained microstructure and consistent mechanical properties throughout 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 reduces hardness, relieves internal stresses, and further improves toughness and ductility, which are critical for high-temperature service.

Ultrasonic Testing (UT)

All plates undergo 100% ultrasonic inspection to detect internal defects such as laminations, porosity, or cracks, ensuring the structural integrity required for pressure vessel applications.

Mechanical Property Testing

Tensile tests, impact tests (typically at 0°C or as specified), and hardness tests are conducted. The material must meet or exceed a minimum yield strength of 310 MPa, a tensile strength range of 515–690 MPa, and a minimum elongation of 18%.

Chemical Analysis

Chemical composition is verified for each heat to ensure chromium, molybdenum, carbon, and other elements remain within the specified ranges.

                                                                                                    Dimensional and Surface Inspection

                                                                                                    Plates are checked for surface defects such as cracks, seams, or indentations.                                                                                                                    Thickness, width, and length are also verified to meet customer and standard                                                                                                                      requirements.

                                                                                                    Delivery Condition

                                                                                                    SA 387 Grade 11 Class 2 is normally supplied in the normalized and tempered (N+T)                                                                                                          condition.

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What is the maximum service temperature for SA 387 Grade 11 Class 2?

It is commonly used in service temperatures up to approximately 500°C (930°F). Beyond this temperature, creep strength and oxidation resistance may become insufficient, and higher alloy grades such as SA 387 Grade 22 or Grade 91 may be required.

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.

Is SA 387 Grade 11 Class 2 suitable for welding?

Yes, it has good weldability, but due to its Cr-Mo composition, preheating and post-weld heat treatment (PWHT) are generally recommended. Proper welding procedures help prevent cold cracking and ensure that the weld joint maintains the required strength and toughness.

What preheat and PWHT temperatures are typical for SA 387 Grade 11 Class 2?

Preheat temperatures typically range from 200–300°C, depending on plate thickness and welding consumables. PWHT is usually performed at 620–680°C to relieve residual stresses and improve the toughness of the weld and heat-affected zone (HAZ).

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.

Can SA 387 Grade 11 Class 2 be used in hydrogen service?

Yes, its Cr-Mo composition provides good resistance to hydrogen attack at elevated temperatures, making it suitable for hydrogenation reactors, reformers, and other equipment in hydrogen-rich environments. However, service conditions such as temperature, pressure, and hydrogen partial pressure must be considered to ensure long-term reliability.

What thickness range is SA 387 Grade 11 Class 2 available in?

It is commonly produced in thicknesses from 6 mm up to 150 mm or more, depending on the manufacturer's capabilities and customer specifications. Thicker plates may require additional heat treatment or testing to ensure mechanical properties are maintained through the cross-section.

What non-destructive testing (NDT) is typically applied to SA 387 Grade 11 Class 2 plates?

Common NDT methods include ultrasonic testing (UT) for internal defects, radiographic testing (RT) for weld inspections, magnetic particle inspection (MPI) for surface cracks, and liquid penetrant inspection (LPI) for detecting surface discontinuities. The specific tests are usually specified in the purchase order and must comply with ASME and other applicable standards.

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.