Manual valves play an indispensable role in industrial piping systems and are mainly used to regulate the flow state of fluids. Its performance and service life are significantly affected by pressure fluctuations within the piping system. Understanding the sources of pressure fluctuations and the mechanisms by which they affect manual valves is crucial to optimizing the design of the valve and extending its service life.
The definition and sources of pressure fluctuations
Pressure fluctuation refers to the instantaneous change of fluid pressure in the pipeline, which is usually caused by the following factors:
1. Changes in fluid flow: Changes in flow velocity will directly lead to pressure fluctuations. For example, operations such as the opening and closing of valves and the starting or stopping of pumps will cause instantaneous changes in fluid flow, which in turn will lead to pressure fluctuations.
2. Equipment failure: Equipment failure, such as pump failure or pipe blockage, will lead to unstable fluid flow, thereby causing pressure fluctuations.
3. Changes in the external environment: Changes in temperature or fluid properties may also cause pressure fluctuations in the pipeline.
The influence mechanism of pressure fluctuation on valve body
The impact of pressure fluctuations on the manual valve body is mainly reflected in the following aspects:
Stress concentration: During the pressure fluctuation process, the valve body experiences instantaneous pressure changes, causing stress concentration inside the valve body. Especially in connection parts or welding points, pressure fluctuations may cause excessive local stress, which may lead to material fatigue or cracks.
Fatigue damage: When exposed to pressure fluctuations for a long time, the valve body material will experience repeated stress, leading to material fatigue damage. Although the initial damage is not easy to detect, over time, tiny cracks will gradually expand and may eventually cause the valve body to rupture or leak.
Decreased sealing performance: Frequent high-pressure and low-pressure switching affects the sealing performance of the valve body. Sealing materials (such as O-rings, gaskets, etc.) age or deform due to stress changes, resulting in a decrease in sealing performance and further leakage.
Valve body deformation: Under extreme pressure fluctuation conditions, the valve body may undergo plastic deformation. Especially in applications with high-temperature and high-pressure fluids, this deformation not only affects the opening and closing performance of the valve, but may also lead to poor connection between the valve body and the pipeline, increasing the risk of leakage.
Factors affecting valve body
The degree of impact of pressure fluctuations on the manual valve body is closely related to the amplitude and frequency of pressure fluctuations, and is also affected by the following factors:
Valve body material: There are significant differences in the ability of valve bodies of different materials to withstand pressure fluctuations. Metal materials (such as stainless steel, cast iron) usually have better strength and fatigue resistance, while plastic materials may show different fatigue characteristics under high temperature and high pressure conditions.
Valve design: The design structure of the valve, such as the thickness, shape and connection method of the valve body, directly affects its resistance to pressure fluctuations. Reasonable design can effectively disperse pressure and reduce stress concentration.
Working conditions: The working environment of the valve, including temperature and fluid characteristics, will also affect its response to pressure fluctuations. High-temperature fluids may accelerate material aging, while corrosive fluids may weaken the valve body.
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