1. Preparation

　　1-1. Select wrenches, screwdrivers, crowbars, afterburners, jack screws and other tools according to the required specifications of the gate valve.

　　1-2. Prepare appropriate amount of cotton yarn and detergent, and prepare gate valve end face gaskets, fillers, lubricants, etc. according to gate valve specifications.

2. Operation steps

　　2-1. Operate the gate valve to the fully open position.

　　2-2. Cut off the front and rear control valves of the gate valve to be dismantled, and vent the remaining medium in the pipe.

　　2-3. Use a wrench to remove the flange bolts connecting the gate valve and the pipeline, tie the appropriate part of the gate valve with a sling, and lift the gate valve with suitable lifting equipment.

　　2-4. Disassemble the middle flange, check and clean the valve cavity, gate, valve stem head, middle flange gasket, etc.

　　2-5. The damaged middle flange gasket needs to be replaced again. Before installation, apply a layer of butter on both sides of the gasket.

2-6. After cleaning, put the valve stem into the gate, align the gate guide groove with the guide rib of the valve body, install the valve body, turn the handwheel, make the two flanges close and align, install the bolt, Angle fastening nut.

　　2-7. After debugging, perform pressure test according to the corresponding test procedure of the valve.

　　2-8. Pack tools and clean the scene.

3. Matters needing attention

　　3-1. When disassembling, it is strictly forbidden to collide with the sealing surface of the disc and the valve seat, and pay attention to the direction of the installation surface of the disc, and mark it before disassembling.

　　3-2. All parts and components should be thoroughly cleaned.

　　 3-3. As far as possible, all parts should be installed in the original state and adjusted to a reasonable position.