What is ASME SA387 GR.12 CL 2 steel Plate？

SA 387 Grade 12 Class 2 is a chromium-molybdenum alloy steel plate under the ASME SA 387 standard, intended for elevated-temperature pressure vessel and boiler service. It provides good high-temperature strength, creep resistance, and oxidation resistance, and is typically used in refineries, petrochemical plants, and power generation facilities. Class 2 represents a normalized and tempered heat treatment for enhanced toughness and ductility.

Equivalents

Tensile Requirements for ASME SA387 Grade 12 Alloy Steel Plates Class 2 Plates

Chemical Requirements for ASME SA387 Grade 12 Alloy Steel Plates

applications

• Pressure vessels and boilers: It is commonly used in the fabrication of pressure vessel shells, heads, and other structural components that operate at elevated temperatures. Its chromium-molybdenum composition provides excellent creep resistance and high-temperature strength, making it suitable for both fire-tube and water-tube boilers.

• Refinery and petrochemical equipment: The material is extensively employed in refineries for reactors, heat exchangers, and fractionation columns. These components often experience high temperatures and corrosive environments, and SA387 Grade 12 Class 2's combination of strength and toughness ensures long-term reliability.

• Power generation systems: It is used in power plants for boiler tubes, headers, and steam piping components. The steel's ability to withstand continuous high-temperature service makes it ideal for both fossil fuel and some types of waste-to-energy plants.

• Chemical processing industry: SA387 Grade 12 Class 2 plate is used in the construction of process vessels and heat exchangers in chemical plants, where resistance to thermal stress and oxidation is essential.

• Oil and gas industry equipment: It finds application in upstream and downstream oil and gas facilities, including pressure vessels, separators, and high-temperature piping systems.

Overall, SA387 Grade 12 Class 2 plate is a versatile material chosen for its excellent high-temperature properties, toughness, and suitability for critical pressure-containing applications across multiple industries.

processing

1. Steelmaking & Casting

Melting: Typically produced via Electric Arc Furnace (EAF) or Basic Oxygen Furnace (BOF).

Refining: The steel must be killed (deoxidized) to ensure a uniform chemical structure. Vacuum degassing is often employed to minimize impurities like hydrogen and oxygen.

Rolling: Plates are primarily Hot-Rolled (HR) to achieve the required thickness and dimensions.

2. Heat Treatment (Critical for Class 2)

To achieve the higher strength required for Class 2, the plates must undergo specific thermal treatments:

Annealing or Normalizing: Heating to the austenitizing temperature to refine grain structure.

Tempering: Reheating to a minimum temperature of 1150°F (620°C) to improve toughness and ductility while maintaining high tensile strength (450–585 MPa).

Optional Accelerated Cooling: In some cases, liquid quenching or air blasting is used before tempering to enhance mechanical properties.

3. Fabrication & Welding

Cutting: Methods include Plasma, Flame, or Water-jet cutting. Preheating may be necessary for flame/plasma cutting to prevent edge cracking.

Preheating (Welding): A preheat temperature of 150°C to 200°C is typically required to avoid cold cracking.

Consumables: Compatible filler metals such as E8018-B2 (for SMAW) or ER80S-B2 (for GMAW) are used to match the 1% Cr - 0.5% Mo composition.

Post-Weld Heat Treatment (PWHT): Mandatory for stress relief, usually performed between 650°C and 700°C.

4. Testing & Quality Control

Mechanical Testing: Includes tensile, elongation, and yield strength verification.

Non-Destructive Testing (NDT): Standard procedures involve 100% Radiography (RT) or Ultrasonic Testing (UT) to ensure internal integrity.

Impact Testing: Charpy V-Notch tests are performed to assess low-temperature toughness, sometimes down to -52°C.

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What is the modulus of elasticity of this grade?

Its modulus of elasticity is about 200 GPa (29×10⁶ psi) at room temperature, consistent with most low-alloy steels for structural design.

What non-destructive testing (NDT) methods are used for this material?

Common NDT methods include ultrasonic testing (UT), radiographic testing (RT), and magnetic particle testing (MT) to detect internal and surface defects.

Is this material resistant to hydrogen attack?

Yes, it has good resistance to hydrogen attack when properly heat-treated. It is suitable for environments with hydrogen at elevated temperatures and pressures.

What is the maximum thickness available for SA 387 Grade 12 Class 2 plates?

Plates are available up to 200 mm (7.87 inches) thick. Thicker plates may require special heat treatment to ensure uniform mechanical properties.

What is the thermal conductivity of this material at room temperature?

At room temperature, its thermal conductivity is about 42 W/(m·K). This property is crucial for heat transfer calculations in heat exchanger design.

Does SA 387 Grade 12 Class 2 have good creep resistance?

Yes, it has excellent creep resistance. The chromium-molybdenum alloying prevents permanent deformation under long-term high-temperature and pressure loads.

Can this material be used in oil and gas refineries?

Absolutely. It is widely used in oil and gas refineries for reactors, boilers, and heat exchangers, enduring high temperatures and corrosive media.

Can SA 387 Grade 12 Class 2 be formed by bending?

Yes, it can be bent with proper procedures. Preheating may be needed for thick sections to avoid cracking, and bending radius should be controlled.