Technical failures, as the name suggests, are caused by the fact that the current technology of hard-tight ball valves is not perfect enough. In many cases, we can only try to reduce the impact caused by it, but it is difficult to completely eliminate it. Of course, if a hard-sealed ball valve with a service life of 3 months can be extended to half a year after troubleshooting or prevention, it can be considered a success even if the failure cannot be eliminated.

1. Leakage caused by damage to the sealing surface

From the working principle of the ball valve, the ball valve is an opening and closing part. Its operation process is the process of opening or closing the steel ball on the valve seat. If the sealing surface is damaged during the opening or closing process, the sealing surface may be damaged. Leakage, resulting in internal leakage of the valve, the valve is invalid.

2. Reasonable selection of valve seat spring

The biggest difference between a hard-sealed ball valve and a soft-sealed ball valve is that the steel ball and the valve seat are both metal materials, unlike the soft-sealing steel ball, which is metal, while the valve seat is non-metallic. Therefore, the sealing mechanism is also different. The sealing principle of the soft sealing ball valve is: the sealing force between the steel ball and the valve seat causes the non-metallic valve seat to deform, and the uneven line contact between the valve seat and the steel ball is transformed into contact, At the same time, after the soft-sealing valve seat is squeezed and deformed, it further fits with the surface of the steel ball to compensate for the unevenness of the steel ball surface. If the extrusion deformation of the steel ball and the valve seat is larger or smaller, it will not affect the sealing performance. The sealing principle of the hard-sealed ball valve is that the sealing force between the steel ball and the valve seat is difficult to deform the metal valve seat.

3. Adjustment of Seat Seal Assembly

The elasticity of the spring and the amount of compression are linear or quadratic curve functions, and the effective value range is very short, so it is only adjusted in a very small range. When the valve leaks and the pressure is higher than the standard or lower than the standard valve position, it needs to be adjusted by the thickness of the sealing assembly installed behind the valve seat.

4. Sealing surface leakage caused by working conditions

This kind of problem generally occurs in the coal chemical industry and the polysilicon industry. The common feature of these working conditions is that the medium is not composed of a single gas or liquid, and there are a large number of solid particles in it. Causes strong scouring, and even enters the sealing surface through the flow channel opening, which can cause fatal damage to the sealing surface.

5 The torque is too large

According to statistics, the leakage of the sealing surface accounts for 20% of the total failures, and the problem of excessive torque accounts for at least 40% of the failures. Due to its special sealing mechanism, the torsion force of the hard-sealed ball valve is 3-4 times larger than that of the soft-sealed ball valve of the same specification. Outside the sealing surface, the torsion force of the steel ball is extremely large when it is opened and closed, and even the phenomenon of "stuck" occurs. If it is forced to open and close, it may even cause the valve stem to be twisted.