Questions about the operating temperature of steel plates for containers?

Firstly, this temperature should be the design temperature, as it is determined by taking into account various operating conditions of the equipment. Therefore, the temperature for selecting materials should also be the design temperature; only in cases where special factors such as corrosion or the effects of hydrogen are considered is the operating temperature taken into account based on long-term impacts. As for whether to consider the ambient temperature, a comprehensive assessment is required; the regulations specify that ambient temperature needs to be taken into account only for those devices that are affected by it during operation. For example, if an air storage tank is not equipped with heating or insulation, the temperature of the equipment under pressure will reach the ambient temperature. In such cases, the ambient temperature must be taken into account in the design, with the design temperature being set at the lowest average temperature of the coldest month. If there is material present during equipment operation, this material can maintain the equipment’s temperature and provide insulation, so it is not necessary to take the ambient temperature into account.

NB/T 47003.12009 does not specify how to determine the ambient temperature value

Then how should it be considered when separated? Listen to insightful opinions. .

Oh, I didn’t realize it was a container at atmospheric pressure; actually it’s the same. The key is to determine whether the equipment is affected by ambient temperature. If there is no heating and the storage container lacks insulation, then considerations are needed. But if it’s a buffer tank or similar device where the material inside is constantly moving in and out and its temperature remains stable, or if there is heating to prevent freezing, then no special considerations are required.

Regarding the application range of Q235B material, the notes state that cylindrical and rectangular containers exposed to the atmosphere are not covered by the aforementioned application range; however, the specific minimum applicable temperature is not specified. It seems that these containers can be considered for use in conditions of low temperature and low stress. Standard NB/T 47003.1-2009 does not contain any provisions regarding flat-bottomed structures; it also removes the vertical cylindrical storage tanks specified in JB/T 4735-97. As a result, there is no basis left for the design standards of many flat-bottomed structures with capacities ranging from a few cubic meters to several dozen cubic meters. If it is a flat-plate structure, it is recommended to select materials in accordance with GB50341-2014.

The operating temperature for Q235B steel plates is 0°C, referring to the average temperature of the shell thickness during operation. When the average monthly minimum temperature is below 0 degrees, it should be considered as a low-temperature and low-stress condition.

These are basic conceptual issues: design temperature, operating temperature of the material, and average temperature of metal components. The maximum design temperature of a component is the upper limit for the operating temperature of the material. Components can also be used for a short period at temperatures higher than the upper limit for use, but this should be specified in the design documents; under normal circumstances, the temperature should not exceed the upper limit specified for the material.

What is considered now is low temperature, with the equipment outdoors. It’s about considering temperatures below 0 degrees; what you said doesn’t seem to be very helpful.

Low temperature and low stress apply in conditions where the design temperature is below -20°C

If the lower limit is considered, for pressure vessels at normal pressure, it could be a condition of low temperature and low stress. Do the calculations first, and then take into account factors such as the medium conditions (temperature, pressure), the average temperature of the shell walls, and the volume. Consider what damage could occur if the equipment fails, and conduct a comprehensive assessment to determine whether Q235B is an appropriate choice. For equipment without insulation measures, the ambient temperature still needs to be taken into account, especially for storage containers.