Valve Selection Principles and Steps
Selection Principles:
1. Safety and Reliability: Industries such as petrochemicals, power plants, and metallurgy demand continuous, stable, and long-term operation. Therefore, it is crucial to choose
valves with high reliability and a significant factor of safety to ensure the device's long-term operational requirements are met.
2. Process Compatibility: Valves should meet the specific requirements of the medium used, working pressure, working temperature, and intended purpose. This is a fundamental criterion for valve selection.
3. User-Friendly Operation, Installation, Maintenance, and Upkeep: Valves should be installed in a manner that enables operators to easily identify the valve's direction, opening indicators, and indication signals. This facilitates prompt and decisive handling of any emergency faults that may arise.
4. Economy: While meeting the operational demands of process pipelines, preference should be given to valves with relatively low manufacturing costs and simple structures. This approach helps reduce device costs, minimize valve raw material waste, and lower the overall expenses associated with valve installation and maintenance in the long run.
Selection Steps:
1. Identify Valve Working Conditions: Determine the valve's working conditions based on its purpose within the device or process pipeline. Consider factors such as the working medium, working pressure, and working temperature.
2. Determine Sealing Performance Level: Based on the working medium, working environment, and user requirements, select the appropriate sealing performance level for the valve.
3. Choose Valve Type and Driving Method: Consider the purpose of the valve and select the appropriate type, such as block valves, regulating valves, safety valves, or other special-purpose valves. Also, determine the driving method, such as worm gear, worm, electric, pneumatic, etc.
4. Match Nominal Parameters: Ensure that the nominal pressure and size of the valve are compatible with the installed process pipeline.
5. Decide Connection Form: Based on the actual operating conditions and the valve's nominal size, choose the suitable connection form between the valve end face and the pipeline. Options include flanges, welding, clamps, or threads.
6. Consider Structural Form: Take into account the installation position, space constraints, and nominal size to determine the appropriate structural form of the valve type. Examples include non-rising stem gate valves, angle globe valves, fixed ball valves, etc.
7. Select Correct Materials: Based on the medium's characteristics, working pressure, and working temperature, choose the appropriate materials for the valve casing and internal components in a correct and reasonable manner.