How to select materials for external pressure vessels in low ambient temperatures

When selecting materials for external pressure vessels in low ambient temperatures, it is indeed necessary to consider the material’s performance at low temperatures. A decrease in temperature causes the material to become more brittle, reducing its load-bearing capacity and resistance to impact. Therefore, it is necessary to choose low-temperature steel or conduct low-temperature impact tests on commonly used steel. Low-temperature steel, through special treatment, is able to maintain its toughness and strength in low-temperature environments, making it suitable for use in cold or frigid conditions. If the ambient temperature is very low, it is recommended to use low-temperature steel. For environments that are not extremely cold but still relatively low in temperature, common steel grades can be considered; however, it is necessary to conduct low-temperature impact tests to verify whether their performance at the intended operating temperature meets the required standards. In short, the material selection must be determined based on the specific ambient temperature and the operating conditions of the pressure vessel. .

Thank you for the reply. Is low-temperature brittle fracture caused by the combined effect of low temperature and tensile stress? In the case of pressure vessels, where the shell is subjected to compressive stress, can it be considered under conditions of low temperature and low stress?

Low-temperature brittle fracture does indeed occur more easily under the combined effect of low temperature and tensile stress. However, although pressure vessels are primarily subjected to compressive stresses, in practical applications, certain parts of the vessel may experience local tensile stresses due to structural irregularities, stress concentration from assembly, or certain conditions during use (such as loading processes or temperature changes). Although these tensile stresses may not be the primary stresses, they can still trigger low-temperature brittle fracture under low-temperature conditions. Therefore, even for externally pressurized vessels that are primarily under pressure, the risk of brittle fracture in low-temperature environments cannot be completely ignored when considering material selection. Even under conditions of low temperature and low stress, it is still necessary to consider the toughness of the material in such an environment. This is why, even for pressure vessels exposed to external pressures, it remains important to choose materials with good low-temperature performance or to conduct low-temperature impact tests on commonly used materials when the operating temperature is very low. This ensures that the container can operate safely and reliably under all possible operating conditions, preventing brittle fracture that may occur at low temperatures. .

You’re welcome! If you have any other questions or need further assistance, feel free to ask at any time. .