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Dismantling steps of electric gate valve

by:Sino Valves     2021-02-26
The specific steps for the disassembly of the electric gate valve are as follows: (1) First, remove the dust on the outside of the gate valve. (2) Mark the valve body and bonnet (to prevent misalignment during assembly), and then place the valve stem in the open state. (3) Remove and disassemble the transmission device. (4) Remove the packing gland nut, exit the packing gland, and remove the packing. (5) Remove the bonnet nut, remove the bonnet, and remove the gasket. (6) Unscrew the valve stem, remove the disc, and keep it properly. (7) Remove the threaded sleeve and flat bearing. The first step: the disassembly of the high-voltage electric open-rod wedge gate valve ①Transfer the maintenance work ticket and confirm that there is no water or pressure in the pipeline before starting work; ②Prepare tools, scaffolding and lifting points; ③Contact the operating personnel for power failure , The power distribution personnel remove the wire; ④ manually open the valve 1-2 buckle to prevent the gate and the valve seat from jamming; ⑤ use the guide chain, wire rope, and use the hoisting ring on the electric mechanism to hoist the electric mechanism, but do not affect the hand Rotate the wheel, remove the fastening bolts between the electric mechanism and the bracket, turn the hand wheel, so that the electric mechanism is lifted smoothly while withdrawing, and placed on the rubberized ground; ⑥Remove the connecting bolts between the bracket and the valve seat , Use the guide chain to hang down; ⑦use the top wire on the pressure plate to loosen the sealing plate downward, remove the pressure plate bolts, remove the pressure plate, the opening stop ring and the sealing ring; ⑧use the guide chain to hold the valve stem together with the seal When the gate and valve stem are exposed, remove the valve stem, lift off the valve stem, sealing plate, etc., remove the packing gland and sealing plate; ⑨make a mark , Take out the gate on the side of the valve body, and seal the valve body port. Step 2: Inspection and repair of high-voltage electric open-rod wedge gate valve ① Inspect the transmission performance of the electric mechanism, ensure that the worm gear and worm are not severely worn, the joint surface of the electric head does not leak oil, and the switching handle is flexible and not jammed. Fill or replace according to the situation lubricating oil. ②Record the original stroke and adjustment of the valve for adjustment after maintenance. Open the gear box cover, remove the worm gear and worm for inspection. The wear should not exceed 1/3 of the tooth thickness, and there should be no cracks or poor meshing in the meshing part. Check the bearing for wear, inflexible rotation or abnormal noise, etc. The bearing clearance should meet the standard. Check whether the coupling part connected to the motor is complete and reliable. The sealing surfaces of the box body should be cleaned, and the gasket should be intact to ensure tightness and no oil leakage. Clean the bearing and the box body, install the worm gear, worm, etc. in turn, add enough lubricating oil (grease) to the box body, seal the box cover, and do the electric and manual switching test, which should be flexible and reliable. ③Check the bracket and valve seat for cracks, blisters and other defects. If any, dig out the defects and repair them. ④ Check the pressure plate, there should be no obvious deformation, otherwise it should be corrected. ⑤Stop the split ring, clean and remove the scale, measure, clean and check the sealing ring. The clearance between the sealing ring and the sealing disc and valve seat should be within 0.2mm without damage or deformation. ⑥ The mating surface of the sealing disc and the valve seat should be free of strains or groove marks, and there should be no bad phenomena such as seizure when mating with the valve seat. ⑦The gap between the packing gland and the door stem and the sealing plate is generally between 0.2-0.25mm. ⑧The valve stem screw buckle is intact, has no damage, fits well with the nut, no bending, corrosion, etc. When the width of the threaded button is more than 1/5, the valve stem should be replaced. ⑨ The sealing surface of the gate and the valve seat should be flat and smooth, free of pitting, corrosion, scouring grooves and other defects. When doing the bonding test, the circle contact and the valve line are clear. ⑩Check and clean all fastening bolts and nuts, and apply lead powder oil. Step 3: Assemble the high-pressure electric rising rod wedge gate valve ①When reinstalling, ensure that the inside of the valve body and all parts are clean; ②Replace the new sealing packing; ③Reinstall the valve in the opposite steps of disassembly. 1. Preparations    1. Select tools such as wrenches, screwdrivers, crowbars, afterburners, jack screws, etc. according to the required specifications of the electric valve.  2. Prepare appropriate amount of cotton yarn and detergent, and prepare valve end face gaskets, fillers, lubricants, etc. according to valve specifications. 2. Operation steps    1. Operate the electric valve to the fully open position.  2, cut off the front and back control valves of the gate valve to be dismantled, and vent the remaining medium in the pipe.  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.  4. Disassemble the middle flange, check and clean the valve cavity, gate, valve stem head, middle flange gasket, etc.   5. The damaged middle flange gasket needs to be replaced again. Before installation, apply a layer of butter on both sides of the gasket. 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 bolts, Angle fastening nut.  7. After debugging, carry out pressure test according to the corresponding test procedure of the valve.   8. Pack tools and clean the scene. 3. Technical requirements    1. When disassembling, it is strictly forbidden to collide with the sealing surface of the gate and the valve seat, and pay attention to the direction of the installation surface of the gate, which can be marked before disassembly.  2. All parts and components should be thoroughly cleaned.  3. As far as possible, all parts should be installed in the original state and adjusted to a reasonable position.
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