Issues with entering the design temperature for low-temperature containers
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When dealing with a carbon steel buffer tank intended for use at an ambient temperature of -30 degrees, and where the operating temperature of the medium is only 30 degrees, should the design temperature of this container be specified as just -30 degrees, or as -30/50 degrees? When preparing the calculation sheet, do I need to prepare a separate calculation sheet for each of these two temperatures?
Normally, it should be written as -30/50, but in some places the quality inspection departments require only one value to be specified, while when renewing the certificate both values are required. In our company, the highest temperature is recorded in the field for the design temperature, and the lowest temperature is recorded in the field for the lowest allowable operating temperature of the metal. Calculations are generally performed under the most stringent design conditions.
When designed in accordance with GB150, this approach is reasonable, as low temperatures only affect material selection, structural design, and manufacturing inspection requirements, but not strength calculations. If designed according to ASME standards, low temperature is also reflected through MDMT, but whether to exempt the calculation of low-temperature impact tests needs to be specified in the calculation report. These two standards adopt different approaches to dealing with the issue of low-temperature brittle fracture; GB150 relies on empirical judgment, whereas ASME is based on fracture mechanics.
Two should be written. High temperatures are used for calculations, while low temperatures are used for material selection...
Does that mean the design temperature is simply written as 50, with an additional column indicating the minimum design metal temperature at -30?
We directly specified the temperature as -30/50; the calculation sheet only shows a high temperature of 50 degrees