1. The design of the auxiliary sealing structure for the closure of plug valves: vacuum vulcanization and special anti-corrosion to ensure the sealing performance
The most critical indicator in the design and manufacture of the main valve structure is the sealing performance. The sealing material used for valve switches is usually rubber, but in the transportation pipeline for conveying refined oil, a simple rubber seal may not be enough. Because the refined oil is an organic solvent, it will dissolve the rubber to a certain extent over time, making the seal invalid. For this reason, advanced technologies such as vacuum vulcanization and special anti-corrosion are adopted on the sealing slide, and the fluororubber sealing ring is permanently embedded in the metal matrix to form the main seal, so as to ensure the good sealing effect and long service life of the sealing slide.
The main valve closing pair adopts the split structure of the seal and the cock. The sealing slide plate with the special rubber fixed is connected through the dovetail groove on the wedge-shaped cock to form a complete closing auxiliary structure. The special shape of the cock also has the advantage that its structure can realize the self-locking function of the fluid. When the cock is pressed, the force of the fluid on the sealing slide plate will not cause any movement of the cock. This forced sealing structure ensures the sealing. reliability.
2. The design of the main valve body of plug valves: double block and double break to ensure fire prevention and leakage prevention
Due to the particularity of the material for conveying refined oil, the design of the main valve body of the plug valve should also take special consideration into the fireproof and explosion-proof performance. After the cock is pressed and the valve is closed, since there are sealing slide plates on both sides of the cock, the upstream and downstream of the pipeline are in an independent sealing state, and at the same time, the strict shut-off and fire resistance requirements of the upstream and downstream are met. In this way, even if there is an accident and leakage occurs on one side, it will not affect the sealing of the other side.
Moreover, in the design process of the main valve body, the metal base of the sealing slide plate and the valve body are basically fitted in the closed state, so that basically in the case of fire, the rubber part of the seal is burned, and there will be no large amount of refined oil. leakage. At the same time, in addition to the rubber O-ring seal between the shaft seal, the upper end cover, the lower end cover and the valve body, a graphite packing or graphite gasket is also set up to further ensure the fire resistance and sealing requirements. In addition, considering that the bottom of the plug valve in use is easy to accumulate dirty oil and impurities, the bottom structure of the main valve is designed as an inclined plane, and a globe valve is set at the lowest position to make the discharge of dirt smoother, the operation is more convenient, and frequent sewage discharge can be avoided. Causes damage to the thread of the drain hole of the lower end cover.
3. The structural parameters of the plug valves are matched to protect the structure of each part from being damaged
In addition to the main valve structure, another important structure of the plug valve is the operator. The function of the manipulator is to convert the multi-turn motion of the actuator into 90-degree rotary motion and up and down linear motion, so as to realize the rising, falling and forward and reverse rotation of the cock. Since there are many parts involved and the stress condition is complex, it is necessary to coordinate the structural parameters of the relevant parts, otherwise the structure will be easily damaged. In the development, the load characteristic requirements of the manipulator are obtained by analyzing the load characteristics of the main valve, and the force analysis of the relevant parts and the finite element stress analysis of the key parts are carried out, and the structural parameters are selected and optimized.
In addition, the plug valve adopts a double-opening structure design at the top and bottom, which can quickly conduct online inspection, repair or replacement of internal components on site without removing it from the pipeline, which is convenient for maintenance; it also has a variety of medium and The cavity pressure relief device can meet the needs of different applications.