What to do regarding material selection for pressure vessels in low-temperature and low-stress conditions above -20°C?
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In GB150, when the design temperature is below -20°C, materials can be selected based on low-temperature and low-stress operating conditions. So what does -15°C count as? I want to use steel 20-8163 for one of my filters; the actual operating temperature is -15°C. How should this be explained?
According to GB150, steel grade 20 cannot be used at -15°C. Q345D from 8163 can be used.
It’s that below -20 degrees, I can choose 20-8163 as it suits low temperatures and low stress, but it doesn’t work at -15 degrees?
You can also design it for low temperature and low stress
What I said on the 2nd floor refers to normal design conditions; low temperatures and low stresses represent special cases. In any case, the allowable stress of materials remains unchanged below 20 degrees. If you’re not concerned about wasting materials, you can opt for a design with low temperature and low stress.
We actually used -15 degrees and made a filter made of 20 steel. The client stated that at temperatures below -20 degrees, it cannot be considered as low-temperature and low-stress conditions; therefore, low-temperature steel is required. Or give a statement or standard
Standardly, they won’t give you such a specification; you can set the design temperature lower than -20 degrees, but the pressure remains fixed and may not result in lower stress. Unless it’s low stress, then isn’t that meeting the requirements of low temperature and low stress?
Try not to use low temperature and low stress treatment, as this condition is very difficult to achieve and will cause problems during future reviews