Selection principles

1. Safety and Reliability

Industries such as petrochemicals, power plants, and metallurgy demand continuous, stable, and long-term operation. Therefore, the valves used must exhibit high reliability and safety factors. Valve failures should not lead to major production safety incidents or personal injuries, meeting the requirements for long-term operation of the facilities.

2. Fulfillment of Process Production Requirements

Valves should meet the needs of the medium, operating pressure, working temperature, and specific purposes, which are fundamental requirements for valve selection. For instance, if a valve is required for overpressure protection or to discharge excess medium, safety valves or relief valves should be selected. If prevention of medium backflow during operation is necessary, check valves should be employed. Automatic expulsion of condensate, air, and other non-condensable gases continuously generated in steam pipelines and equipment while preventing steam leakage should be achieved using steam traps. Additionally, corrosion-resistant materials should be chosen when dealing with corrosive media.

3. Convenient Operation, Installation, and Maintenance

After valve installation, it should allow operators to correctly identify the valve direction, opening indication, and signal indication, facilitating prompt and decisive handling of various emergency faults. Meanwhile, the selected valve type structure should be as simple as possible, facilitating installation, inspection, and maintenance.

4. Economy

Under the premise of ensuring the normal operation of process pipelines, valves with relatively low manufacturing costs and simple structures should be selected as much as possible to reduce equipment costs, avoid waste of valve raw materials, and reduce the expenses associated with valve installation and maintenance in the later stages.

Selection steps

1. Based on the application of valves in equipment or process pipelines, determine the operating conditions of the valves. For example, working medium, working pressure, and working temperature.

2. Based on the working medium, operating environment, and user requirements, determine the sealing performance level of the valve.

3. Based on the purpose of the valve, determine the type and actuation method of the valve. Types include gate valve type, globe valve type, safety valve type, and other special-purpose valve types. Actuation methods include worm gear, electric, pneumatic, etc.

4. Selection based on the nominal parameters of the valve. The determination of the nominal pressure and nominal size of the valve should match the installed process pipeline. Valves are installed in process pipelines, so their operating conditions should be consistent with the design choices of the process pipeline. Once the standard system and nominal pressure of the pipeline are determined, the nominal pressure, nominal size, and valve design and manufacturing standards can be determined.

5. According to the actual operating conditions and the nominal size of the valve, determine the connection form between the valve end face and the pipeline, such as flange, welding, clamp, or threading.

6. Based on the valve's installation position, installation space, and nominal size, determine the structural form of the valve type, such as rising stem gate valve, angle globe valve, floating ball valve, etc.

7. Select the materials for the valve body and internal components based on the characteristics of the medium, working pressure, and operating temperature in a correct and rational manner.