The reason why stainless steel screws and stainless steel nuts cannot be used together is that after the stainless steel bolts and stainless steel nuts are fastened during the assembly of low-temperature pipeline flanges, the phenomenon of seizure often occurs, and it is difficult to remove them.

Solution:

1. Cryogenic treatment. A treatment that intrudes the parts into a low-temperature liquid nitrogen box for a certain period of time to reduce their deformation due to temperature difference and changes in metallographic structure, thereby improving the sealing performance of the valve at low temperature;

2. The nut is directly changed to copper nut;

3. Use anti-seize agent;

4. Apply some grease to the threaded rod before tightening the nut.