Introduction to high-pressure flat gate valves for mining/coal mining

End User:
Sany Automobile Manufacturing Co., Ltd.
Operating Conditions Description: The customer installs valves in the pipeline to cut off the medium. Because the medium is a viscous filler-like substance with a high solid content and high pressure, strong erosion is considered, so a high-pressure parallel slide gate valve is considered as a shut-off valve.
According to the on-site operating conditions, a high-pressure parallel slide gate valve with an upper guiding hole is selected. A guiding hole is designed on the upper part of the valve plate. When the valve stem moves upward, the valve closes; when the valve stem moves downward, the valve opens. In this way, the valve plate is always in contact with the sealing surface of the valve body, preventing the medium from eroding the sealing surface. Part of the residual medium brought into the upper chamber through the upper guiding hole will be brought into the channel by the valve plate when the valve is opened next time, preventing accumulation and blockage. At the same time, in order to cope with possible scouring and erosion, tungsten carbide spraying hardening treatment is adopted on the sealing surfaces of the valve plate and valve body to improve the hardness of the sealing surface and prevent damage to the sealing surfaces of the valve plate and valve body.

I. Product Features:
1. The valve seat adopts an O-ring seal and a pre-stressed floating valve seat structure, which makes the valve inlet and outlet bidirectional sealing; and the opening and closing torque of this structure is only 1/2 of that of ordinary valves, which can easily open and close the valve.
2. With the upper guiding hole valve plate, whether it is fully open or fully closed, it always fits the sealing surface, and the sealing surface is not directly eroded by the medium, thus prolonging the service life.
3. The valve adopts a packing structure with self-sealing capability, which does not need frequent adjustment, is extremely easy to open and close, and has reliable sealing performance. An auxiliary sealing grease injection structure is set at the packing gland, the sealing performance is absolutely reliable, and truly achieves zero leakage; it solves the problem that the packing gland of general valves is most prone to leakage.
4. When the valve is closed, it can automatically relieve the high pressure in the cavity (see the working principle diagram for details), ensuring safe use.
II. Working Principle:
1. When the internal pressure of the valve is equal (1), the gate plate is in the closed state, and the PTFE sealing ring on the valve seat surface forms the initial seal. Each time the valve is opened or closed, the valve seat ring can clean both sides of the gate plate. (Figure 1)

2. When pipeline pressure is applied to the valve (2), the pressure acts on the gate plate, forcing it to close to the PTFE ring on the outlet valve seat, compressing it until the gate plate stops on the steel valve seat. In this way, a double seal is formed, first PTFE to metal seal, then metal to metal seal, and the valve seat is also firmly pushed to the recess. At this point (3), the O-ring prevents any rear medium flow. (Figure 2)

3. After the valve cavity pressure is released, an inlet seal is formed, and the pipeline pressure acts on the inlet valve seat (4), causing it to move toward the gate plate. At this time, a PTFE-to-metal seal is formed, and at the same time, the O-ring (5) forms a tight seal with the valve seat recess. (Figure 3)

The valve automatically releases excess pressure. When the valve cavity pressure is greater than the pipeline pressure, due to thermal expansion, the inlet valve seat is pushed toward the recess, and the excess pressure in the valve cavity is released into the pipeline between the valve seat and the gate plate. (Figure 4)