1. The structure adopts the eccentric-wedge principle. The rotation center of the valve body and valve core (i.e., the valve stem axis) is offset by a radial dimension from the geometric center of the sealing spherical surface of the valve core, and is also offset from the valve seat sealing surface on the valve body channel axis. The sealing pair is Metal-to-metal contact under the action of external force, the valve relies on two eccentricities to achieve self-locking closing. The reasonable selection of eccentricity makes the self-locking angle smaller than the friction angle. If the self-locking angle is too small, it is easy to close, but it is extremely difficult to open. If the angle is selected too large, Although the opening force is small, the closing torque increases rapidly. Repeated tests on the test bench are crucial to determine the two reasonably matched eccentricities. The reliable self-locking performance ensures a tight seal. This is the core technology of the semi-ball valve. In terms of structural principles and manufacturing methods to achieve optimal sealing, ball valves, butterfly valves, gate valves, globe valves, etc. are indeed inferior.
​2. It is extremely easy to achieve and maintain zero leakage for a long time. The seal between the valve core and the valve seat is a spherical line contact, which is self-locking by eccentricity. The sealing pair has almost no contact during the whole process of opening and closing. Only at the moment of opening and closing, it will contact and tighten the gate to achieve zero leakage, ensuring dynamic and static sealing. There are no leak points anywhere. For scale or other accumulation on the valve seat, the valve core has the ability to powerfully remove scale during the process of contacting the valve seat. During the frequent reciprocating movements of opening and closing of the gate valve’s sealing surface, the mixed-flow medium scales and settles in the lower cavity of the valve body. The stop valve completely relies on positive pressure to achieve sealing, and the scale on the valve seat has no cleaning ability. The two are entangled. Frequent and repeated wear can easily cause internal and external leakage of gate valves and globe valves. The ball valve seal relies on the valve seat being squeezed on the spherical surface for a long time. It wears faster than the semi-ball valve. The butterfly valve seal is made of rubber, which is far inferior to the metal hard sealing performance of the semi-ball valve, ball valve and gate valve. After long-term use of the semi-ball valve, the valve seat will also suffer slight wear. It can continue to be used through adjustment. During the opening and closing process of the valve stem and packing, the valve stem only needs to rotate 90°. When there is any sign of leakage, tighten the packing gland again. With just a few bolts, there can be no leakage in the packing. However, other valves are still barely used with small leaks, and the valves with big leaks must be replaced.
3. Extremely easy to operate. During the entire process of opening and closing of the hemispherical valve, the sealing pair is almost completely in an undamped idling state. The external force is only detached or compressed at the moment of opening and closing, and the valve stem only needs to rotate 90°, which is light and fast. Of course, it is easy to operate. During the opening and closing process, the ball valve operates under the holding force of the valve seats at both ends. It has a larger opening and closing torque than the semi-ball valve. The larger the nominal diameter, the more obvious the difference in opening and closing torque. The opening and closing of the butterfly valve must overcome the deformation of the rubber. To achieve, the torque is larger. The operation of gate valves and globe valves is long and laborious.
4. Long service life. The sealing pair is bimetallic, with alloys of different uses overlayed on the parent body. After special heat treatment, its mechanical properties and physical and chemical indicators reach the best state to meet different working conditions (strong wear, rapid erosion, severe corrosion, etc. media) According to the needs of the valve, the hardness of the valve seat is slightly lower than that of the valve core. The materials and heat treatment processes are different. When necessary, the hardness of the sealing pair can reach above HRC53 and can withstand high temperatures of 560°C. Practice has proven that its anti-corrosion and anti-seizure capabilities are 6 times that of stainless steel sealing pairs. The valve can be opened and closed tens of thousands of times without failure, extending its service life.
5. Wide range of applications. Shanghai Hugong Valve Factory’s multi-series semi-ball valves are widely used in non-ferrous smelting, gas and natural gas, pulverized coal injection and dust removal in steel, power slag transportation, harmful gases (hydrogen sulfide, phosgene, etc.) and oil products (heavy oil, crude oil , residual oil, etc.) smelting and transportation. The reason why it has a wide range of applications is mainly because the sealing pairs are overlayed with different alloys to make them bimetallic. The main parts such as the valve body and valve stem are made of the required materials to meet different working conditions, forming a variety of Hugong valves. Product Series.