ASTM A387 Grade 22 Class 2 (A387GR22CL2) chromium-molybdenum steel plate is the preferred material for manufacturing high-temperature and high-pressure equipment due to its strong high-temperature performance, hydrogen corrosion resistance, and weldability.

Key Features and Advantages

Excellent High-Temperature Strength: Maintains high strength at elevated temperatures (typically up to 550-600°C) with minimal susceptibility to creep deformation.

Good Hydrogen Corrosion Resistance: The addition of chromium and molybdenum enables resistance to hydrogen atom erosion in environments such as petroleum refining and coal chemical processing, preventing hydrogen-induced cracking and hydrogen blistering.

Good Toughness and Plasticity: The normalizing and tempering treatment provides a favorable combination of mechanical properties.

Weldability: As a medium-alloy steel, it offers acceptable weldability but requires strict welding procedures, including preheating and post-weld heat treatment, to prevent cold cracking and restore the properties of the heat-affected zone.

ASTM A387 Grade 22 Class 2 (A387GR22CL2) steel plate is primarily used in the manufacturing of pressure equipment operating in high-temperature and/or hydrogen-rich environments, such as:

1. Petrochemical industry: Hydrogenation reactors, reforming units, synthesis towers, and other high-temperature and high-pressure equipment.

2. Power industry: Supercritical boiler drums, high-temperature pipelines, and steam turbine components.

3. Energy sector: Coal chemical industry gasifiers, LNG storage tanks, and nuclear pressure vessels.

4. Special environments: Hydrogen-containing media (e.g., refinery hydrocracking units) and sulfur corrosive environments.

Welding Precautions

Welding material selection: Matching chromium-molybdenum welding wire (such as ER80S-B3) or electrodes (such as E8018-B3) to ensure the weld metal composition matches the base material.

Preheating and interpass temperature: Preheat to 150-250°C, with interpass temperature not lower than the preheat temperature to prevent cold cracking.

Post-weld treatment: Mandatory PWHT (690-730°C × 2h) to eliminate the risk of hydrogen-induced cracking and improve joint performance.

Machining Precautions

It can undergo cold working such as cutting, bending, and stamping, but care must be taken to control the amount of deformation to avoid stress concentration.

The hot working temperature is recommended to be controlled between 900-1100°C, avoiding prolonged exposure in the sensitive range of 800-950°C.