ASTM A387 Grade 12 Class 1 (A387GR12CL1) is a well-balanced and technologically mature chromium-molybdenum alloy steel. It achieves an excellent balance among high-temperature strength, hydrogen corrosion resistance, and manufacturability, making it one of the "workhorse" materials in the manufacturing of pressure vessels for the petrochemical, coal chemical, and power industries. The key to its application lies in strict adherence to manufacturing processes, particularly proper welding and heat treatment procedures.

Key Features and Advantages

Excellent High-Temperature Strength: The addition of chromium and molybdenum significantly enhances the steel's creep resistance (slow deformation under prolonged heat and stress) and long-term strength at high temperatures.

Good Resistance to Hydrogen Corrosion: Molybdenum effectively resists hydrogen corrosion that occurs in high-temperature, high-pressure hydrogen environments, which is why it is critical in petrochemical equipment.

Good Oxidation Resistance: Chromium forms a dense oxidized chromium protective film on the steel surface, slowing down further high-temperature oxidation.

Yuxin Steel supplies steel plates within the following specification ranges: thickness 6-300mm, width 1500-4050mm, length 3000-15000mm, with support for custom cutting and bevel processing.

Due to the excellent high-temperature performance and hydrogen resistance of A387GR12CL1 steel plate, it is widely used in the manufacturing of:

1. Petroleum refining equipment: Hydrogenation reactors, catalytic cracking units, high-pressure separators, heat exchangers, and other equipment exposed to high-temperature hydrogen environments.

2. Coal chemical equipment: Coal gasifiers, shift converters, etc.

3. Thermal power plants: Boiler drums, high-temperature superheaters, reheaters, headers, and main steam lines (particularly in areas where temperature and pressure are not extremely high).

4. Other high-temperature and high-pressure pressure vessels: Various chemical containers that require long-term stable operation at certain temperatures.

Welding Precautions

Welding ASTM A387 Grade 12 Class 1 (A387GR12CL1) steel plate requires special care to prevent hydrogen-induced cracking (cold cracking):

Electrode selection: Typically, matching low-hydrogen welding consumables such as AWS A5.5 E8018-B2 (electrode) or AWS A5.28 ER80S-B2 (wire) are selected.

Preheating: Preheating is mandatory, with a temperature generally recommended between 150°C and 200°C, depending on the plate thickness.

Interpass temperature: The interpass temperature must be controlled during welding, approximately within the same range as the preheating temperature.

Post-weld heat treatment: Mandatory requirement. Hydrogen removal treatment must be performed immediately after welding, followed by a full normalizing + tempering or stress relief annealing to restore the properties of the heat-affected zone and eliminate residual stress. The typical PWHT temperature ranges from 620°C to 680°C.

Usage Precautions

Temperature Limits: The recommended long-term service temperature should be ≤500°C, with a short-term peak temperature not exceeding 530°C. If higher temperatures are required, upgrade to Grade 22 (2.25Cr-1Mo).

Stress Control: Avoid the formation of high residual stresses in welds and heat-affected zones. It is recommended to employ vibratory stress relief or furnace-based overall tempering to eliminate stresses.

Corrosion Protection: In environments containing Cl⁻, control the surface roughness to Ra ≤ 3.2μm and conduct regular penetrant testing (PT) to prevent stress corrosion cracking.