Common Valves in the Refining and Chemical Industry

Gate valves are frequently used in the refining and chemical industry, and when properly applied, they allow liquid flow direction to remain unchanged. When fully opened, gate valves have an exceptionally low resistance coefficient and are available in a wide range of sizes, pressures, and temperature capacities suitable for the industry. Gate valves  require relatively little installation space and can be used in a variety of conditions. However, they also have certain disadvantages, including a relatively tall structure, slow opening and closing times, erosion-related damage to the sealing surface during operation, and stringent cleanliness requirements for the medium. If non-metallic corrosion-resistant materials are used, there are also high technical and operational risks. When a gate valve is opened, the likelihood of eddy currents forming behind the gate increases, which is a primary cause of erosion and vibration. If personnel do not identify and address this issue promptly, prolonged eddy currents behind the gate may impair the valve's function and lead to failure. Given these factors, gate valves are not ideal for adjusting flow in refining and chemical production, and other valves may be preferable. When applying gate valves, it is essential to analyze the operating environment and function and to compare the performance of rising stem and non-rising stem gate valves. For corrosive environments, rising stem gate valves perform better; in low-pressure environments without corrosive media, non-rising stem gate valves provide effective regulation.

Ball valves are commonly used in the refining industry. They perform exceptionally well in environments with high or low temperatures or high-viscosity media. If the medium contains suspended solid particles, most ball valves on the market can handle this condition, provided that installation and operation standards are followed. Full-bore ball valves are commonly used for flow regulation and are relatively rare in other applications. In emergencies within refining and chemical production, full-bore ball valves enable rapid shut-off. With the development of the refining and chemical industry, increasingly specific operational standards have been established. Ball valves are essential in applications requiring strict sealing and wear resistance, as well as high-pressure shut-off and rapid opening and closing. They are ideally suited for handling corrosive media and lighter structural applications. Additionally, they perform effectively with low-temperature and cryogenic media.


 

Check valves are suitable for clean media. According to current operational standards, check valves require a high level of media cleanliness. When the diameter (DN) does not exceed 40 mm, a lift check valve should be selected and installed in the designated position to function effectively. For DN ranges between 50 and 400 mm, a swing check valve is recommended. This valve performs well in both horizontal and vertical pipelines; however, its specific application should be assessed based on the actual flow direction of the media. For DN ≥ 450 mm, a buffer check valve is preferable due to its superior performance. For DN between 100 and 400 mm, a butterfly check valve is commonly used. Based on experience in the refining field, swing check valves have a strong bearing capacity and can operate reliably even under high pressure. This type of check valve can function effectively in various complex conditions.


 

In certain refining and production operations where fluid resistance is not strictly regulated, a globe valve may be selected. This valve can achieve the desired effect even under high-temperature and high-pressure conditions. Various types of globe valves are available and should be selected based on specific requirements, such as for DN ≤ 200 mm in steam pipelines. To maximize the globe valve’s role in the pipeline, its position should be optimized, with tests, comparisons, and analyses conducted for precise positioning. For small valves, such as sampling valves, needle valves, instrument valves, exhaust valves, or valves in low-vacuum systems, globe valves perform well, though proper operating procedures must be followed. Compared to other valves, the globe valve can adjust flow and control pressure. Thus, high precision in adjustment is not required for specific applications. As long as the pipeline diameter is not large, the globe valve can be placed in a specific position.


 

The structure of the throttle valve is similar to that of the globe valve, but there are significant differences in their application conditions and functions. In addition, the throttle valve lacks a throttling element and is relatively compact. It offers high reliability and significant energy savings during use, and external factors rarely impact its effectiveness. However, the throttle valve has disadvantages, including limited control and adjustment capabilities, with a tendency for errors to occur frequently. Comprehensive analysis indicates that in refining, throttle valves are suitable for low-temperature, high-pressure media. When flow and pressure adjustments are needed, a throttle valve can fulfill this purpose. A throttle valve should not be used with unclean or high-viscosity media.
 

The butterfly valve has minimal fluid resistance and is easy to open and close. In refining applications, the weight, structure, and size of the butterfly valve contribute to its effective performance. For cut-off and throttling requirements in refining, the butterfly valve is suitable. However, for large-flow regulation, considering the limitations of sealing materials, it may not be fully applicable, and other valves may be needed. In systems with liquid media containing suspended solids and large-diameter pipelines, butterfly valves can be installed in suitable locations.


 

In the refining industry, plug valves are often the first choice. They offer excellent sealing performance, bidirectional sealing capabilities, flexible and rapid opening and closing motions, and high durability. Refining processes frequently involve the use of hazardous materials. In this context, plug valves have distinct advantages; however, they require relatively high torque for opening and closing. After prolonged use, plug valves do not accumulate liquid in their cavities, preventing contamination of the materials in intermittent devices.


 

Diaphragm valves are relatively common in the refining industry. In certain applications, they utilize rubber and plastic membranes to precisely control the direction and state of the fluid flow. In practice, when a diaphragm valve is employed, the resistance encountered by the fluid is minimal and nearly negligible. This feature allows for two-way sealing when needed. When handling low-pressure, suspended viscous fluids, diaphragm valves are preferred, and their installation in specific positions can effectively regulate flow. The diaphragm material exhibits excellent temperature resistance, providing optimal conditions for the diaphragm valve.