At present, the general top entry ball valve has four threaded holes symmetrically machined at the front and rear of the valve body, and the valve seat head is designed into a special structure with an inclination. The valve seat is supported by an outer adjusting rod, and then the ball is installed, and then the adjusting rod tooling is removed. Tighten the threaded holes with four plugs to realize valve installation. Although this structure can meet the online maintenance function, it adds four leakage points, which is easy to cause medium leakage. At the same time, when designing a high-pressure valve, this structure is not reliable, there is a potential safety hazard that the plug is blown out of the plug by the high-pressure medium, and it cannot meet the function of online maintenance. When the top-mounted ball valve fails during use, the valve can only be removed from the pipeline, the valve assembly components are pulled to both sides of the valve channel with tooling, and then the ball is taken out, and the remaining internal components are taken out for maintenance.

The current relatively new top entry ball valve structure includes a valve body, a spring seat and a valve seat seat. The valve body has a boss, the valve seat head has a thread, a nut is on the thread, and a spring seat has a clamping groove.

The installation method of the new top-mounted ball valve is as follows:

1. Place the tooling assembly vertically on the operating platform, sleeve the inner hole of the valve seat retainer on the tooling assembly, and assemble the spring seat, spring and universal plug to form the outlet valve seat assembly and the inlet valve seat assembly;

2. Lift the outlet valve seat assembly from the upper part of the valve cavity with locks and eye bolts, and at the same time hoist another inlet valve seat assembly into the valve cavity;

3. Screw the four connecting rods into the threaded holes of the tooling assembly. After they are installed in the cylinder assembly, they are connected to the connecting rods through the connecting pins. The cylinder assembly is stretched by the hydraulic pressure to push the tooling assembly on both sides to make the outlet valve The overflow plugs on the seat assembly and the valve seat assembly at the inlet end are pressed into the passage holes on both sides of the valve cavity;

4. Clamp the card holder in the slot of the spring seat, then install the limit block between the card holder and the boss, and then complete the installation of the remaining three card holders and the limit block;

5. Take out the cylinder assembly and tooling assembly of the top-mounted ball valve, install it in the sphere and rotate it 90 degrees, then install it from the top, screw the connecting rod into the threaded hole of the nut, and use oil pressure to shrink the cylinder assembly To the design distance. Because the nut and the valve seat are connected by threads to form a component, the nut and the valve seat are pulled by the cylinder to approach the ball, and the spring seat is resisted by the clamping seat and the limiting block through the boss, so that the nut is separated from the spring seat.

6. Tighten the nut to make it close to the spring seat and compress the spring until the spring seat is separated from the clamping seat by the extension of the cylinder assembly. Take out the clamping seat and the limit block, and then take out the cylinder assembly to complete the assembly of the top-mounted ball valve.

The advantage of this new type of top entry ball valve is that the head of the valve seat has a thread to cooperate with the nut, and the nut is tightened. The yielding space of the valve seat is generated, and the overflow plug in the traditional low-temperature top-mounted ball valve is prevented from idling during the valve opening and closing process, and the sealing reliability of the overflow plug is improved. Avoid installing the threaded holes of the valve body to prevent medium leakage; with the help of cylinder components and tooling components, valves can be installed to achieve online maintenance functions.