Key Points for Controlling Materials in Low-Temperature Pressure Vessels

The quality of low-temperature pressure vessels relies heavily on the materials used, particularly low-temperature steels. These steels are categorized based on usage temperatures, such as -40℃ and above, -40 to -196℃, and -196 to -273℃. Commonly used materials include 16MnDR, 15MnNiDR, 09Mn2VDR, and various nickel-based low-temperature steels.

The primary failure mode of steel at low temperatures is brittle fracture. It is crucial to control the steel’s toughness at low temperatures, reflected in impact values and sensitivity to crack propagation. Material procurement involves strict specifications for smelting methods, chemical composition, internal structure, and heat treatment to ensure high-quality low-temperature steel.

1.1 Inspection of Low-Temperature Materials

After entering the factory, low-temperature steel undergoes retesting to ensure material quality. It includes chemical composition, room temperature mechanical properties, low-temperature impact values, and ultrasonic testing.

Procurement of welding rods and fluxes should match the chemical composition and mechanical properties of the base metal. Strict management protocols for low-temperature steel materials, including labeling, transportation, and storage, are crucial to avoid accidents.

1.2 Management of Low-Temperature Materials

Establishing rigorous systems for issuing, retrieving, and on-site management of low-temperature steel materials is crucial for ensuring the quality of low-temperature pressure vessels. Proper labeling, handling, and storage procedures are essential to prevent confusion with ordinary steel.