[Discussion Thread 13] Under what circumstances should both ambient temperature and operating temperature be considered?
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This post was last edited by kareale88 on 2019-2-17 at 18:45 with bg14.jpg【Discussion Thread 13】Regarding pressure vessels – under what circumstances should both the ambient temperature and the operating temperature be taken into account? ——Under what circumstances should only the ambient temperature be considered — under what circumstances should only the operating temperature be considered — and under what circumstances should both the ambient temperature and the operating temperature be taken into account? If the operating temperature of a device is 10°C and the ambient temperature is -40°C, then what should be the design temperature for this device in the absence of any insulation?
1. First, determine whether it is a process device or a storage device. 2. Are there any heating or insulation measures in place? 3. In the absence of insulation and heating measures, the metal wall temperature of process equipment must be considered comprehensively, and care should be taken when selecting low-temperature steel. Storage containers are highly affected by ambient temperature; it is recommended to take this into account when making decisions!
If the operating temperature is specified, has the impact of ambient temperature been taken into account?
There is no such parameter as usage temperature in container design; instead, there are operating temperature or design temperature. Refer to HGT20580.
Ultimately, it still comes down to the metal temperature of the container shell. I always believe that the temperature of the container under normal operation is its maximum operating temperature, which is also the temperature measured by the thermometer. For storage containers, the ambient temperature is used; for devices intended for other purposes, the aforementioned measured temperature is used, which is essentially the operating temperature.
For pressure vessels stored at room temperature, in the absence of insulation measures, their design temperature shall not be higher than the lowest value of the monthly average minimum temperatures over the years. For other cases, the provisions in HG/T20580 shall apply.
If the operating temperature of a separation device is 10°C and the ambient temperature is -40°C, then when designing such a device without insulation, should the temperature value considered be positive or negative? :handshake
In this case, the wall temperature of the container is certainly affected by the ambient temperature. It’s not wrong to indicate a positive value for temperature in the diagram, but it has no practical significance. What needs to be considered is the situation at low temperatures.
I can understand what you mean. How should I understand the operating temperature specified by the customer? In GB150, there is a prerequisite regarding the design temperature: the vessel is under normal operating conditions.......
It’s somewhat similar to work pressure; in fact, it is the pressure obtained by subtracting atmospheric pressure from the absolute pressure. Gauge pressure. So, if the customer specifies the operating temperature and the ambient temperature, then is the operating temperature the difference between these two values after accounting for the ambient temperature?
The temperature provided by the user should be the operating temperature, while the ambient temperature should be based on the lowest average monthly temperature over the years in the location where the container will be used (this information needs to be obtained through research). The design temperature (the temperature of the metal) takes into account both the operating temperature and the ambient temperature. Theoretically, calculating this using heat transfer principles is complicated and generally not practical. If the operating temperature is not high itself (operating at normal temperature per the specifications), for a conservative design, the design temperature should take the ambient temperature into account.