Process Description of Dissolved Air Flotation
May 15,2023Read More
Valves for chemical industry are a major accessory for fluid control in industrial pipelines, facing a variety of working conditions due to the disorderly and complex types of valves in the industrial system. To select suitable valves for pipeline systems, one should understand the function of valves, grasp the process and criteria for selecting valves, and follow the guidelines for selecting valves for the petroleum and chemical industries.
Valves for chemical industry not only have a wide range of applications, but also have high requirements compared to ordinary valves. The media commonly used in valves for chemical industry are relatively easy to corrode. From simple chlor-alkali industries to large-scale petrochemical enterprises, there are dangers such as high temperature, high pressure, corrosion resistance, wear resistance, and large temperature and pressure differences. For valves used in this type of application environment, strict compliance with chemical specifications should be followed in the selection process.
The principles for selecting valves for chemical industry: valves with straight through channels have lower flow resistance and are usually chosen as valves for shut-off and open media. Valves that are easy to adjust flow are used for flow control; plug valves and ball valves are more suitable for diversion and distribution applications; and valves that have a wiping effect with sliding seals along the sealing surface are most suitable for media with suspended particles.
The common valves for chemical industry are ball valves, gate valves, globe valves, safety valves, plug valves, check valves, etc. The media in valves for chemical industry contain corrosive substances, and the complex corrosive media of acid and alkali require the use of alloy steel or fluorine-lined valves.
Gate-type valves: used for blocking or communicating fluid in the pipeline.
Regulating-type valves: used to regulate flow rate and velocity in the pipeline.
Throttling-type valves: used to cause a significant decrease in pressure after the fluid passes through the valve.
Other types: actively blocking or maintaining a certain pressure, and preventing gas and water.
Check for defects such as sand holes and cracks on the inside and outside of the valve body.
Check if the valve seat and valve body joint are firm, if the valve core and valve seat match, and if there are defects on the sealing surface.
Check if the valve stem and valve core connection are flexible and reliable, if the valve stem is bent, and if the thread is damaged.
With the advancement of technology, automated valves for chemical industry have also been quickly promoted in chemical production. They can achieve accurate control of flow rate, pressure, liquid level, and temperature. In the automatic control system of chemical production, regulating valves belong to a major actuator. The model and installation quality of the regulating valve have a significant impact on the quality of the control loop. If the selection and use of the regulating valve are not appropriate, it will seriously threaten the service life of the regulating valve, and even cause system shutdown in severe cases. With the development of industrial automation, pneumatic regulating valves have also been widely used as excellent actuators.
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