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Selection and use of ball valve

发表时间:2020-12-11 11:49

1、 Ball valve temperature and pressure limits

The name plate shows the maximum allowable operating pressure of the ball valve at the maximum and minimum operating temperature.

For PTFE or rtfe seats and seals, the operating temperature should be between - 290 ℃ and 2000 ℃. The operating temperature of other types of seats and seals should be checked by the factory.

The nominal pressure rating (PN) of the valve indicates the maximum working pressure of the valve at normal temperature. For example, pn4.0 indicates that the maximum working pressure is 40 bar (4.0 MPa) when the operating temperature is - 290 ℃ - 380 ℃.

For the precautions of electric or pneumatic actuators, please refer to the corresponding instructions.

2、 Installation of ball valve

1. Remove the protective covers on both sides of the flange end, and flush and clean the valve when the valve is fully open.

2. Before installation, the whole machine shall be tested according to the specified signal (electricity or gas) (to prevent vibration caused by transportation and affect the service performance), and the installation can be carried out on line after passing the test (refer to the circuit diagram of electric actuator for wiring).

3. Before preparing to connect to the pipe, flush and remove the remaining impurities in the pipe (which may damage the valve seat and ball).

4. During installation, please do not use the actuator part of the valve as the lifting point to avoid damaging the actuator and accessories.

5. This kind of valve should be installed in the horizontal or vertical direction of the pipeline.

6. The pipeline near the installation point shall not be low hanging or bear external force, and the pipe support or support can be used to eliminate the deviation of the pipeline.

7. After connecting with the pipe, cross lock the flange connecting bolts with the specified torque.

3、 Operation and use of ball valve

1. Make sure that the pipeline and valve have been flushed before operation.

2. The operation of the valve is driven by the input signal of the actuator to complete the rotation of the valve stem: when the forward rotation is 1 / 4 turn, the valve is closed; when the reverse rotation is 1 / 4 turn, the valve is opened.

3. When the direction indicator arrow of the actuator is parallel to the pipeline, the valve is in the open state; when the indicating arrow is vertical to the pipeline, the valve is in the closed state.

4、 Ball valve maintenance

A longer service life and maintenance free period will depend on the following factors: normal working conditions, maintaining a harmonious temperature / pressure ratio, and reasonable corrosion data.

be careful:

When the ball valve is closed, there is still pressure fluid in the valve body

Before maintenance, relieve the line pressure and keep the valve in the open position

Before maintenance, disconnect the power or air source

Before maintenance, separate the actuator from the bracket

1. The packing must be locked again

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.

2. Replace seat and seal

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 driving device, actuator, connecting bracket, lock washer, stem nut, butterfly spring piece, gnan, wear-resistant piece and valve rod 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.


Add:CHAODA GROUP,JIANGBEI STREET,OUBEI,YONGJIA,WENZHOU,CHINA                                            

Code No: 325105

Tel:+86 577-67319962