What attention should be paid to the daily maintenance of ball valve?

The long service life and maintenance free period will depend on the following factors: normal working conditions, harmonious temperature / pressure ratio, and reasonable corrosion data. When the ball valve is closed, there is still pressure fluid inside the valve body. Before maintenance: relieve the pipeline pressure and keep the valve in the open position; disconnect the power supply or air source; separate the actuator from the support It is found out that the upstream and downstream pipes of the ball valve can be disassembled only after the pressure has been removed. During disassembly and reassembly, care must be taken to prevent damage to the sealing surface of the parts, especially non-metallic parts. Special tools should be used when taking out the O-ring. During assembly, the bolts on the flange must be tightened symmetrically, gradually and evenly.

The cleaning agent shall be compatible with rubber parts, plastic parts, metal parts and working medium (such as gas) in ball valve. When the working medium is gas, the metal parts can be cleaned with gasoline (gb484-89). Non metallic parts shall be cleaned with pure water or alcohol. After cleaning, the non-metallic parts shall be taken out of the cleaning agent immediately, and shall not be soaked for a long time. After cleaning, the non-metallic parts shall be assembled after volatilization of the washing agent (silk cloth without cleaning agent can be used), but it shall not be put aside for a long time, otherwise it will rust and be polluted by dust. The new parts shall also be cleaned before assembly, and metal shall not be allowed during assembly Debris, fiber, grease (except those specified for use), dust and other impurities, foreign matters and other pollution, adhere or stay on the surface of parts or enter the inner cavity. If there is micro leakage at the packing, the valve stem nut must be locked again.

Note: do not lock too tightly, usually lock 1 / 4-1 turn, the leakage will stop.

A) , disassembly

Make the valve in the half open position to flush and remove the possible hazardous substances inside and outside the valve body.

Close the ball valve, remove the connecting bolts and nuts on both sides of the flange, and then completely remove the valve from the pipeline.

Remove the drive actuator, connecting bracket, lock washer, stem nut, butterfly spring piece, gnan, wear plate and valve stem packing in sequence.

Remove the connecting bolts and nuts of the body cover, separate the valve cover from the valve body, and remove the valve cover gasket.

Make sure that the ball is in the "off" position, which can be easily taken out of the valve body, and then take out the seat.

Push down the valve stem from the middle hole of the valve body until it is completely taken out, and then take out the O-ring and the lower packing of the valve rod.

Note: Please operate carefully to avoid scratching the surface of the valve stem and the sealing part of the stuffing box of the valve body.

B) Re assembly

Clean and inspect the removed parts. It is highly recommended to replace the seals such as valve seat and bonnet gasket with spare parts package.

Assemble in the reverse order of disassembly.

Cross lock the flange connecting bolts with the specified torque.

Lock the stem nut with the specified torque.

After the actuator is installed, the corresponding signal is input and the valve core is driven to rotate by rotating the valve stem to make the valve open and close.

If possible, please carry out pressure seal test and performance test for valve according to relevant standards before reassembling pipeline.

1. Principle

The opening and closing part of the ball valve is a ball. The ball rotates around the center line of the valve body to open and close.

2. Applicable place

Low pressure, small diameter pipeline is used to cut off the water flow and change the distribution of water flow or need to open and close quickly.

3. Features

1) The flow resistance is small;

2) The structure is simple;

3) Small volume and light weight;

4) The sealing surface material of the ball valve is plastic with good sealing performance;

5) Convenient operation, quick opening and closing, and remote control;

6) The sealing ring is generally movable and easy to disassemble and replace;

7) When the valve is fully open or fully closed, the sealing surface of the ball and valve seat is isolated from the medium, and the medium will not cause the erosion of the valve sealing surface.

4. Classification

1) The commonly used ball valves are divided into floating ball valve, fixed ball valve and lifting rod ball valve according to its working principle.

2) Ball valve can be divided into straight through type, three-way type and right angle type according to its channel position. The latter two kinds of ball valves are used to distribute medium and change the flow direction of medium.

5. Key points of construction and installation

1) The installation position, height, inlet and outlet direction must meet the design requirements, and the connection should be firm and tight.

2) The handle of all kinds of manual valves installed on the insulation pipeline shall not be downward.

3) Before the valve is installed, the appearance inspection must be carried out, and the valve name plate shall comply with the provisions of the current national standard general valve marking (GB 12220). For the valve with working pressure greater than 1.0 MPa and cutting off on the main pipe, strength and tightness test shall be conducted before installation, and the valve can be used only after passing the test. In the strength test, the test pressure is 1.5 times of the nominal pressure, and the duration is not less than 5min. The valve shell and packing are qualified if there is no leakage. During the tightness test, the test pressure shall be 1.1 times of the nominal pressure; the test pressure shall meet the requirements of GB 50243 during the test duration, and the valve disc sealing surface without leakage shall be regarded as qualified.

4) Seal gasket shall be installed between valve flange and pipeline flange according to pipeline design requirements.

5) The ball valve with transmission mechanism shall be installed according to the provisions of the product operation manual.