How to deal with some failures of the ball valve?

A valve in which the ball is driven by the valve stem and rotates around the axis of the valve stem is called a ball valve. It is also a plug valve with a spherical closure. The valve seat matched with the ball is circular, so the sealing stress on the circumference is the same. Most ball valves also use soft seats that conform well to the ductile iron surface.

Ball valve features:

Advantages:

① The structure of the medium and small diameter ball valve is relatively simple, the external dimension is small, and the weight is light.

②Ball valves have low water resistance and have the lowest water resistance among all types of valves. This is because the cross-sectional areas of the valve body passage, the ball passage and the connecting pipe are equal when fully open, and communicate in a straight line.

③ The opening and closing is quick and convenient, and the flow direction of the medium is not restricted.

④The opening and closing torque is lower than that of the plug valve. This is because the contact area of the sealing surface of the ball valve is small, and the opening and closing is less labor-intensive than that of the plug valve.

⑤ The sealing performance is good, because the material of the ball valve sealing ring is mostly plastic, and the friction factor is small; When the ball valve is fully open, the sealing surface is not damaged by the liquid.

The disadvantage of the ball valve is that it is difficult to process and grind the ball.

The common failure of ball valve is that the valve is not closed tightly. So why is that so? There are mainly the following reasons:

1. The sphere is not round and the surface is rough;

2. Sphere overturn

3. The sealing surface of the valve seat is crushed

4. No preload on the sealing surface

5. The closing position indicated by the wrench does not match the actual, resulting in leakage

6. The valve seat and the valve body are not sealed, and the O-ring and other seals are damaged

Preventive measures and exclusion methods:

1. Improve manufacturing quality, dismantling inspection and pressure test before use

2. The assembly should be correct, the operation should be stable, and it is not allowed to be used as a throttle valve. After the ball is overturned, it should be repaired in time and the sealing seat should be replaced.

3. When assembling the valve seat, the valve should be in the fully closed position, the bolts should be tightened evenly, and the force should be small

4. Regularly check the pre-tightening force of the sealing surface, and pay attention to adjusting the pre-tightening force

5. Before use, it should be checked that the closing position indicated by the wrench should match the actual closing position. Periodic correction

6. Improve the assembly accuracy and sealing performance of the valve seat and the valve body. Reduce valve seat loading and unloading times, check and replace seals regularly

Complete solutions for Industrial valves