A387 Gr 11 CL 2 Steel Plate - Pressure Vessel

A387 Gr 11 CL 2 is a type of chrome-moly (chromium-molybdenum) alloy steel plate (ASTM A387/ASME SA387) designed for high-temperature applications, particularly in welded boilers, pressure vessels, and heat exchangers, offering excellent high-temp strength, oxidation, and corrosion resistance due to its ~1.25% Chromium and ~0.5% Molybdenum content, with "Class 2" indicating a higher tensile strength range than Class 1.

processing workflow

1. Cutting and Forming

Cutting: Material is typically cut using CNC Flame, Plasma, or Laser cutting.

Forming: Cold forming is common for thinner plates; however, heavy-wall sections or heads require Hot Forming to reduce residual stresses.

2. Welding Process (WPS)

The high hardenability of Cr-Mo steel requires strict thermal control to prevent cracking:

Preheating: Essential to prevent hydrogen-induced cracking. Preheating temperatures typically range from 150°C to 250°C depending on thickness.

Consumables: Use low-hydrogen electrodes matching the base metal chemistry (e.g., E8018-B2 or ER80S-B2).

Interpass Temperature: Must be strictly maintained (typically <300°C) to prevent grain growth and maintain toughness.

3. Heat Treatment

This is the critical stage to achieve the Class 2 mechanical properties (Tensile strength: 75–100 ksi):

Normalizing: Heating to 900°C–950°C followed by air cooling or accelerated cooling.

Tempering: Conducted at a minimum of 620°C (1150°F) to improve ductility and relieve stresses.

Post-Weld Heat Treatment (PWHT): Mandatory for Grade 11. It is usually performed at 650°C–700°C to ensure the weld zone and heat-affected zone (HAZ) achieve the required toughness.

4. Inspection and Testing (NDT)

Non-Destructive Testing: Includes Ultrasonic Testing (UT) for internal defects, Radiographic Testing (RT) for weld integrity, and Magnetic Particle Testing (MT).

Mechanical Testing: Tensile, Yield, and Elongation tests.

Impact Testing: Charpy V-notch tests at specified temperatures to ensure low-temperature toughness.

Hardness Testing: Maximum hardness is often limited (e.g., ≤225 HBW) to ensure resistance to stress corrosion cracking.

applications

1. Petrochemical & Refinery Industry

This is the most common application sector due to the material's resistance to High-Temperature Hydrogen Attack (HTHA) and sour gas (H₂S).

Hydrogenation Reactors: Used in hydrocracking and hydrotreating units.

Fractionation Columns: Applied in refinery distillation processes.

Separators & Storage Tanks: Specifically for high-temperature fluid and gas storage.

2. Power Generation

In power plants, the steel is valued for its creep resistance and thermal stability under continuous heat.

Boiler Components: Includes boiler drums, steam headers, and superheater tubes.

Turbine Equipment: Used in steam turbine casings and related high-pressure systems.

Nuclear Facilities: Applied in specific pressure-bearing systems within nuclear power plants.

3. Oil & Gas Processing

The material's high tensile strength (75–100 ksi) makes it suitable for heavy-duty pressure equipment.

Heat Exchangers: Specifically shell-and-tube exchangers subject to thermal cycling.

High-Pressure Pipelines: Used for transportation systems handling aggressive chemicals or hydrocarbons.

Gas Handling Systems: Critical for gas processing facilities where corrosion resistance is essential.

4. General Heavy Industry

Pressure Vessels: Standard use in any industrial furnace or high-pressure cylinder.

Chemical Process Equipment: Reactors and vessels handling corrosive, high-temperature chemical reactions.

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Full specification and details are available on request. The above information is provided for guidance purposes only. For specific design requirements please contact our technical sales staff.

What is A387 Gr 11 CL 2?

It is a low-alloy chromium-molybdenum steel plate, mainly used for pressure vessels in high-temperature and corrosive environments, with excellent heat resistance and weldability.

What is the main chemical composition of A387 Gr 11 CL 2?

Key elements: C (≤0.15%), Cr (1.00-1.50%), Mo (0.45-0.65%), Mn (0.40-0.70%), Si (0.50-1.00%), ensuring its high-temperature performance.

What is the minimum tensile strength of A387 Gr 11 CL 2?

Its minimum tensile strength is 415 MPa (60 ksi), and minimum yield strength is 205 MPa (30 ksi), suitable for high-pressure service conditions.

What is the maximum service temperature of A387 Gr 11 CL 2?

It can continuously operate at a maximum temperature of 593°C (1100°F), resisting creep and oxidation under long-term high-temperature exposure.

Which standard governs A387 Gr 11 CL 2?

It complies with ASTM A387, a standard for alloy steel plates for pressure vessels, specifying chemical composition, mechanical properties, and manufacturing requirements.

What is the difference between A387 Gr 11 CL 1 and CL 2?

CL 2 has stricter impact toughness requirements (Charpy V-notch) than CL 1, suitable for lower-temperature or more demanding pressure vessel applications.

Is A387 Gr 11 CL 2 weldable?

Yes, it is highly weldable. Proper preheating (150-260°C) and post-weld heat treatment (PWHT) are needed to avoid cold cracks and ensure joint integrity.

What post-weld heat treatment (PWHT) is required for A387 Gr 11 CL 2?

Typical PWHT: Tempering at 620-677°C (1150-1250°F) for sufficient time, relieving welding residual stress and improving toughness.

What are the common applications of A387 Gr 11 CL 2?

Used in refineries, petrochemical plants, boilers, and nuclear power equipment, such as reactor vessels, heat exchangers, and steam pipes.

What is the thickness range of A387 Gr 11 CL 2 plates?

Common thickness ranges from 6mm to 200mm, customizable for specific pressure vessel designs and load-bearing requirements.