Tilting disc check valve was proudly made in Jitai Valve
2019-07-01 Browse：945
The impact and water hammer phenomena of check valves often occur. When the valve closes, the valve disc does not reach the closing position before the medium backflow, which causes the impact. When the valve opens, because the disc swing arc is too large, the acceleration stroke is too long, it will also cause the impact of the valve body. Swashplate check valves effectively overcome the impact and water hammer phenomena of swing check valves and lift check valves under this working condition, and realize the non-impact operation. Because of the short running distance of the disc, it can quickly reach the seat position of the valve, thus minimizing the impact phenomenon, and moving smoothly, effectively realizing its sealing and action function. Swashplate check valves are designed to prevent backflow of fluid in horizontal or vertical pipelines, in vertical pipelines or in pipelines with any inclined angle between horizontal and vertical.
CL600-28 "36" Used in Class A Pipeline of Ethylene Plant
Research and Development Background of Swashplate Check Valve
At present, there is a big gap between China's valve industry and foreign enterprises in industrial structure, industry chain and professionalization. In the future, product technology will become the key point of innovation in China's valve industry. Speeding up the elimination of inefficient and energy-intensive products, adjusting industrial structure, promoting the development and application of new technologies and new products has become a key driving force for the valve industry to move forward. Jitai Valve has always adhered to the road of innovation and improvement. Constantly adjust the product structure and increase the R&D and investment of new products. Through further design improvement and precise manufacturing, Jitai self-developed and manufactured swashplate check valves fill the domestic gaps in the petrochemical field and play an important role.
Product Design Parameters
Chinese Name: Swashplate Check Valve
Product design: ASME B16.34 GB/T12224
Structure length: ASME B16.10 GB/T12221
Inspection and testing: API 598 GB/T 13927
Flange size: ASME B16.5 GB / HG / SH
Butt welding size: ASME B16.25
Material: WC6
Pressure rating: Class 150, 300, 600, 900, 1500, 2500
PN 2.0, 5.0, 10.0, 15.0, 25.0, 42.0 MPa
Working Principle and Purpose
The main parts of the swashplate check valve include the body, seat and disc. The valve body consists of a valve chamber and an inlet and an outlet, and the valve seat is located at the connecting point between the inlet and the valve chamber. The valve seat is characterized by pendulum motion of the disc assembly through the pivot, and the pivot hole is located above the center of gravity of the whole disc assembly; the pivot is located on one side of the disc assembly, deviating from the plane of the valve body and the valve seat. The sealing form is spherical seal. There will be no friction or sliding contact during the combination and separation of seat and disc. The valve seat, disc and pivot constitute a whole and are fixed on the inlet side of the valve body. Through this structure, the sealing and operation characteristics are realized, and the impact-free and noise-free work is achieved. Micro-elastic metal seat, good sealing performance. Spherical disc design, switching fast, sensitive, long service life. The structure of the swashplate check valve makes the fluid passage streamlined, with low flow resistance and energy saving effect.
Introduction of Main Characteristics
Swashplate check valve is a new type of check valve. Its main characteristics are as follows:
1. Comparing with the swing check valve, the swing check valve adopts plane seal. It needs some accessory parts (such as rocker and fork) to achieve its sealing requirements, while the inclined valve uses spherical seal. The width of the sealing surface of the valve seat is wider than that of the valve disc, which is beneficial to the guide of the valve disc in the process and the coincidence between the sealing surfaces, thus greatly increasing the reliability of the seal. On the contrary, the plane seal of the swing check valve is the opposite. Because the specific pressure of the spherical seal under the action of axial force is usually larger than that of the plane seal, the sealing performance of the valve is better than that of the swing check valve. There will be no friction or sliding contact during the combination or separation of the seat and disc. The conical seat has a certain angle with the flow direction, which can automatically adjust the sealing position of the disc, and can close tightly all the time without medium pressure. Even in vertical (flow upward) pipes, the valve has a particularly tight closing characteristic.
2. The center of gravity of the disc revolving around the axis is shorter than that of the axis, so the pendulum effect of the short arc is smaller. During the opening and closing process, the radius of rotation of the disc is shorter and the swing amplitude is reduced. It can effectively reduce the impact and vibration of the disc and the valve seat, and prevent the occurrence of water hammer phenomenon. When countercurrent occurs, the gravity principle is used to quickly switch off. Closed disc. Because of the short running distance of the disc, it can quickly reach the seating position, thus minimizing the impact phenomenon, and moving smoothly, with high efficiency. Low noise, medium fluctuation is also small, to achieve a silent impact-free effect.
3. Valve disc can be opened to the horizontal position, large opening, strong circulation capacity, small fluid resistance, obvious elimination of water hammer. With the help of medium force and special design of valve disc, when the valve is fully opened, the valve disc can be opened to the horizontal position, which greatly increases the cross-section area of the flow channel, ensures the full flow of medium and ensures the whole pipe. Line circulation capacity.
4. Satisfy horizontal and vertical installation (flow upward).
Key and Difficult Points in Design and Manufacture
4-1. As with other valves, the basic design should be carried out to calculate the specific pressure of seal, shell strength, flange strength, bolt strength, etc. In design, the size and position of internal parts should be determined first, then the size of valve body should be determined. Finally, the die should be fixed. After opening the die, the measurement of the die should be carried out to further confirm the size, and the die should be submitted to the foundry for trial production. On the premise of guaranteeing sealing performance and other functions, functional verification of the trial-produced prototype is carried out.
4-2. In order to achieve good sealing performance between disc and seat, it is necessary to ensure that the center of gravity of the disc is located on the vertical side of the pin axis (revolving axis) when the disc is closed, that is, the side far from the sealing surface. Only in this way can the disc achieve sealing effect under the action of self-weight. Therefore, the design of the center of gravity of the disc becomes the valve. Core design components.
In order to achieve this goal, we used three-dimensional software to assist the design of each valve disc throughout the design process, so that we can determine the center of gravity of the disc, and at the same time, by weighing the weight of the disc, realize the change of the center of gravity of the disc. The weight of the valve disc is added with the die and the weight plate is then fine-tuned in the metalworking process. At the same time, considering the effect of medium force, the opening of valve disc is more convenient. According to the theory of fluid mechanics, the shape of counterweight plate is circular, which is equivalent to the sealing disc. There is hollow between counterweight plate and sealing disc, which is conducive to the "lifting" of medium force and the flow of medium.
4-3. The choice of the rotating axis of the disc should be considered from three aspects.
A. To ensure the smooth flow passage, minimize the pressure drop and avoid excessive swing.
B. On the premise of ensuring the geometric size of the assembly, the structure is compact.
C. To ensure sealing performance, the disc bearing and the pin hole of the valve body should be processed uniformly to ensure the axial consistency.
D. Hardness and wear resistance of seats and disc seals should meet life requirements.
E. Ensure the shape and position tolerance and smoothness of the sealing surface, and enhance the reverse coincidence between disc and seat.
4-4. The radial and axial clearance between pin hole and valve disc should be moderate. It is necessary to avoid the phenomenon of too large clearance leading to inaccessibility of positioning and too large jitter of hoist and to avoid too small clearance leading to the disc unable to automatically adjust the sealing position.
