Manual valves play a vital role in industrial pipeline systems and are mainly used to regulate and control the flow of fluids. With the increasing complexity of industrial production, the application environment of manual valves has also changed, and temperature fluctuations have become one of the key factors affecting the performance of valve bodies.
Definition and source of temperature change
Temperature change refers to the fluctuation of ambient or medium temperature within a specific period of time. In industrial applications, the sources of temperature change mainly include the following aspects:
1. Fluid properties: Different fluids will cause different temperature changes during operation. For example, high-temperature fluids such as steam and hot water will significantly increase the temperature of the valve body when flowing.
2. Equipment operation status: Factors such as equipment start and stop, load changes, etc. will cause fluctuations in the temperature of the fluid in the pipeline, thereby affecting the performance of the valve body.
3. External environment: Changes in the external environment, such as seasonal changes and climate changes, will also affect the temperature of the valve body.
Mechanism of the impact of temperature changes on the valve body
The impact of temperature changes on the valve body of manual valves is mainly reflected in the following aspects:
Thermal expansion and contraction of materials: The valve body material will undergo thermal expansion or contraction when the temperature changes. Although the expansion coefficient of metal materials is relatively small, the dimensional changes of the valve body may still affect the sealing performance under high temperature conditions. If the valve body and the sealing material are not well matched, the seal may fail, causing leakage.
Stress concentration phenomenon: Temperature changes will produce temperature gradients inside the valve body, especially when high and low temperatures are alternating, different parts of the valve body may experience different temperature changes. This temperature difference will cause stress concentration, increase the risk of fatigue of the valve body material, and may eventually cause cracks.
Material property changes: As the temperature changes, the mechanical properties of the valve body material will also change. In high temperature environments, metal materials may experience reduced strength and increased plasticity, while in low temperature environments, the brittleness of the material increases and is prone to brittle fracture. These property changes may affect the load-bearing capacity and durability of the valve body.
Aging of sealing materials: Temperature changes also affect the sealing materials of the valve, such as O-rings and gaskets. In high temperature environments, the aging and failure of sealing materials are accelerated, resulting in reduced sealing performance, thereby increasing the risk of leakage.
Factors affecting valve body performance
The degree of influence of temperature changes on the performance of manual valve body is not only related to the amplitude and frequency of temperature, but also closely related to the following factors:
Valve body material: valve bodies of different materials have different tolerance to temperature changes. Metal materials (such as stainless steel and cast iron) are generally more resistant to high temperatures than plastic materials, but metal materials may show brittleness under extremely low temperature conditions.
Valve design: The design structure of the valve (such as the thickness, shape and connection method of the valve body, etc.) directly affects its resistance to temperature changes. Reasonable design can effectively disperse thermal stress and reduce the risk of material fatigue.
Working conditions: The working environment of the valve (such as fluid type, flow rate and pressure, etc.) will also affect its response to temperature changes. High-temperature fluids may accelerate the aging of materials, while corrosive fluids may weaken the strength of the valve body.
Frequency of use: The more frequently the valve is used, the more temperature changes it is subjected to, and the risk of material fatigue increases accordingly.
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