Such failures include "cooling leakage" and freezing of valve packing, leakage of valve seat and pipe connecting flange, and leakage of valve screw sleeve at both ends of tinned thread. The stem packing is usually located in the packing groove of the stem close to the cold box wall. When the packing is not uniform or tight, and the valve stem is not straight or round, cryogenic liquid or gas will leak along the packing gap. As a result of cold transfer to the outside, the water in the air will freeze on the packing, thus freezing the valve stem. In this case, the valve can only be opened and closed by heating the filling with steam or hot water. However, after opening and closing the valve, the water accumulated in the packing will freeze again. The valve stem is usually twisted and the handwheel is broken due to the hard work of valve opening and closing.
Therefore, after the maintenance of the valve, the packing should be evenly and tightly packed, and the compression nut should b
Jul 26, 2023