Is the normal-temperature tank at a low temperature? How to check?
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This post was last edited by qldch2306 on 2015-7-6 at 10:06. It is a separation tank designed for normal temperature conditions, made of Q345R material; due to an operational error, a cryogenic medium at around -30 degrees Celsius was accidentally introduced into the tank. However, the tank was indeed not designed and manufactured as a low-temperature pressure vessel, and no impact test was conducted. It also does not suit low-temperature and low-stress operating conditions. How should such devices be handled and inspected? Is there any danger? Is the design unreasonable? Should the worst-case conditions be considered for low-temperature vessel design? Thank you
Low temperatures have no lasting effects on steel; they only cause a decrease in toughness and an increase in brittleness when present, but toughness is restored immediately once the low temperature conditions cease. Therefore, I personally believe there is no need for excessive panic; it is sufficient to conduct a thorough inspection of each weld to check for any cracks.
There is definitely a risk; low-temperature conditions can lead to brittle fracture, especially in welds of types A and B, as well as in areas where hidden cracks are likely to form. If it was designed for normal temperature conditions, it is best to drain the medium and conduct a pressure test again, especially in areas prone to cracking (main welds, T-joints, and cross-welds). In fact, it’s best to do everything well). Then use it as a container at room temperature. If it is to be used as a cryogenic container, it is best to redesign it. .