1. Internal Leakage:  

① At cryogenic temperatures, soft seats (PTFE/RPTFE/PCTFE) undergo severe contraction, losing sealing integrity and causing internal leakage.  

② O-ring failure under cryogenic conditions results in internal leakage.  

2. External Leakage:  

An unreasonable extension height of the valve bonnet may easily cause condensed water in the air to enter the packing, where it freezes, scratches the packing, and leads to external leakage.  

3. Jamming:

① Soft seats becomes harder under cryogenic temperature , increasing friction and operating torque sharply, resulting valve jamming. 

4. Safety Hazards: 

① At low temperatures, if temperature rises, the medium in the valve pocket would vaporizes, resulting in a sharp expansion in volume. This leads to a sudden increase in internal pressure of the valve pocket, posing a safety hazard.

② At low temperatures, residual moisture inside the valve freezes, causing a sharp increase in valve torque.