ASTM A387 Grade 5 Class 2 is a chromium-molybdenum alloy steel plate specifically designed for welded pressure vessels and boilers in high-temperature environments, offering excellent high-temperature strength, corrosion resistance, and hydrogen embrittlement resistance. It is an indispensable advanced material for critical equipment in fields such as petrochemicals.

Key Features and Advantages

1. Excellent high-temperature strength: Exhibits higher strength and superior creep resistance compared to carbon steel within the temperature range of 400°C to 550°C.

2. Hydrogen corrosion resistance: The addition of chromium and molybdenum enables resistance to hydrogen attack, hydrogen embrittlement, and hydrogen-induced disbonding in high-temperature and high-pressure hydrogen environments.

3. Good toughness: The normalizing and tempering treatment refines the grain structure and enhances the impact toughness of the material.

4. Weldability: As a medium-alloy steel, it offers acceptable weldability but requires strict preheating, interpass temperature control, and post-weld heat treatment procedures.

ASTM A387 Grade 5 Class 2(A387GR5CL2) Boiler And Pressure Vessel Steel Plate is primarily used in the manufacturing of pressure equipment operating in high-temperature, high-pressure, and hydrogen-containing environments, such as:

1. Petrochemical industry: Hydrogenation reactors, synthetic ammonia equipment, refinery towers, heat exchangers.

2. Power and energy: High-temperature boilers, steam pipelines, nuclear pressure vessels.

3. Natural gas processing: Separators and storage tanks in acidic gas environments (such as H₂S/CO₂).

4. Other industrial equipment requiring resistance to high temperature, high pressure, and corrosion, such as coal chemical gasifiers.

Processing Requirements

Cutting and Forming: Preheating to 150–200°C is required before flame cutting, followed by slow cooling to prevent cracking.

Bending and Stamping: It is recommended to perform these operations in an annealed or normalized state to avoid cold work hardening.

Welding Precautions

Preheating and Interpass Temperature: Preheating to 150–200°C before welding is necessary, with the interpass temperature maintained between 150–300°C to prevent hydrogen-induced cracking.

Welding Methods: Supports SMAW (Shielded Metal Arc Welding), SAW (Submerged Arc Welding), GTAW (Gas Tungsten Arc Welding), and others. The use of low-hydrogen electrodes (e.g., E5MoV) is recommended.

Post-Weld Treatment: Post-weld heat treatment (PWHT) is required at a temperature of 705–760°C. The holding time should be calculated based on the plate thickness (e.g., 2 hours for 25mm) to relieve residual stresses.