Wedge gate valve is a gate valve in which the sealing surface is at a certain angle with the vertical centerline, that is, the two sealing surfaces are wedge-shaped. Wedge gate valves have single or double gate plates. The advantage of the double gate type is that the sealing and angle accuracy requirements are low, temperature changes are not easy to cause the gate to wedge, and gaskets can be added to compensate for sealing surface wear. The disadvantage is that the structure is complex and easy to stick in viscous media. More importantly, the gate plate is easy to fall off after the upper and lower baffles are rusted for many years.
The sealing principle of wedge gate valve:
The sealing principle of the wedge gate valve is achieved by the tight combination of the two sealing surfaces on the wedge gate plate and the two sealing surfaces on the valve body when they are wedged together. The purpose of using a wedge gate is to increase the auxiliary sealing load so that the metal-sealed wedge gate valve can seal both high and low medium pressures. When closing, rotate the valve stem clockwise to make the sealing surface of the gate valve and the valve body sealing surface close to achieve a seal. However, the inlet-end sealing specific pressure generated by the wedge effect of the metal-sealed wedge gate valve is often insufficient to achieve the inlet-end seal due to the force of the medium. Therefore, the metal-sealed wedge gate valve is a single-sided forced seal.
The sealing principle of the wedge gate valve is achieved by the tight combination of the two sealing surfaces on the wedge gate plate and the two sealing surfaces on the valve body when they are wedged together. The purpose of using a wedge gate is to increase the auxiliary sealing load so that the metal-sealed wedge gate valve can seal both high and low medium pressures. When closing, rotate the valve stem clockwise to make the sealing surface of the gate valve and the valve body sealing surface close to achieve a seal. However, the inlet-end sealing specific pressure generated by the wedge effect of the metal-sealed wedge gate valve is often insufficient to achieve the inlet-end seal due to the force of the medium. Therefore, the metal-sealed wedge gate valve is a single-sided forced seal.
The main features of wedge gate valve:
1. Compact structure, reasonable design, good valve rigidity, smooth passage and small flow coefficient
2. The sealing surface is made of stainless steel and carbide, which has a long service life.
3. Using flexible graphite filler, reliable sealing, light and flexible operation
4. The driving modes are manual, pneumatic, electric and gear transmission.
5. The structural form is elastic wedge type single gate, rigid wedge type single gate and double gate type.
Wedge gate valve is suitable for:
Wedge gate valves are widely used in petrochemical industry, thermal power plants and other oil and steam pipelines as opening and closing devices to connect or cut off the medium in the pipelines.
Among various types of valves, gate valves are the most widely used. It is generally only suitable for fully opening or fully closing, and cannot be used for adjustment and throttling. Wedge gate valves are generally used in situations where there are no strict requirements on the external dimensions of the valve and the operating conditions are relatively harsh. For example, the working medium of high temperature and high pressure requires the closing parts to ensure long-term sealing, etc.
The application and working principle of parallel double gate valves appear in most industries and are a type of ceramic gate valves. Therefore, the structure and working principle of the parallel double-gate gate valve are the same as those of the gate valve. Its opening and closing body (valve plate) is driven by the valve stem to move the valve seat sealing surface up and down, which can connect or cut off the fluid channel.
When the valve is partially opened, eddy currents will be generated on the back of the gate, which can easily cause erosion and vibration of the gate, damage the sealing surface of the valve seat, and make maintenance difficult. It is usually suitable for working conditions where frequent opening and closing is not required and the gate remains fully open or fully closed.
Parallel double gate valve product features:
1. This double gate valve has advanced design concepts and incomparable characteristics of ordinary valves. As a hydraulic control system, the product effectively solves the leakage caused by long-term unresolved impurities causing damage to the lock cover.
2. In order to meet the requirements of different users, valves have national standards and American standards. In every system, there are general purpose plate valves and oil field specific valves.
3. This double gate valve adopts a sealing structure and a special type of spring. Make the sealing pair consistent with any position so that residual dirt (such as sediment, welding slag, etc.) can be completely scraped off and can be cut on the cover. damaged and working fine.
4. Since the spring self-sealing structure in the double gate valve can automatically compensate for the normal wear of the valve cover, on the one hand, the sealing leakage rate is strong, on the other hand, the service life of the valve is greatly improved, saving costs for the enterprise.
5. Double gate valves should adopt a wedge-shaped roller switch mechanism to open and close the valve gently. For example, the patented valve PN4.0MPADN300 can be easily opened and closed by just one person using a handwheel. Practice has proved that under the same pressure level and caliber, the opening and closing torque of the patented valve is half that of ordinary valves.
6. Since this product adopts a special switching mechanism, it prevents the normal gate valve from heating up and causing the gate to be killed by the gate.
7. There is an automatic drainage system at the bottom of the double gate valve, which can always keep the valve body cavity free of residue.
8. There is a dust-proof mechanism in the valve body to ensure that the inner cavity of the double gate valve will not be invaded by dirt and the internal mechanism will not fail.
9. The sealing performance is better than that of the wedge gate valve. If the inclination angle of the sealing surface and the valve seat are not very accurate, it still has good sealing performance.
10. After the gate sealing surface is worn, replace the metal pad at the bottom of the spherical top center with a thicker one and use it. Generally, there is no need to surfacing and grinding the sealing surface, which is difficult to achieve with a single gate or elastic gate.
11. There are more parts than other types of gate valves.
12. In addition to being suitable for steam, oil and other media, it is also suitable for parts with frequent opening and closing and media with greater wear on the sealing surface. It is not suitable for media that are prone to coking.
