The reasons why the gate valve is not tightly closed are generally as follows:

1. The valve stem and connecting parts are worn and torn, resulting in the deflection of the gate and the valve seat, which cannot be closely contacted.

2. The valve stem is rusted and cannot be rotated.

3. There are impurities stuck on the sealing surface, and the debris is deposited at the bottom of the valve or between the gate and the valve seat.

4. The sealing surface is damaged, resulting in leakage of the medium.

The solution is as below:

1. Strengthen the management of the gate valve, and regularly fill the oil filling hole of the gate valve with lubricating oil; when the switch gate valve finds that the lubricating oil has deteriorated, it should be replaced in time to ensure the flexibility of the switch.

2. Remove the debris between the valve stem and the nut in time, and regularly maintain and inspect the valve stem and gate to avoid the valve stem or valve support deflection from being unable to be closed into the bottom groove.

3. When the valve body is slightly closed due to the deposition of impurities, the gate valve can be closed and then slightly opened to perform a short-term interception and flushing.