Valve selection principle
The selected valve should meet the following basic principles.
(1) Safety and reliability of petrochemical, power station, metallurgy and other industries require continuous, stable, long cycle operation. Therefore, the valve required should be high reliability, large safety factor, can not cause major production safety and personal casualties because of valve failure, meet the requirements of long cycle operation of the device, and long cycle continuous production is the benefit.
(2) To meet the requirements of process production valve should meet the use of medium, working pressure, working temperature and use needs, which is also the basic requirements of valve selection. If need valve overpressure protection role, discharge excess medium, should choose safety valve, overflow valve, need to prevent the operation process of medium backflow, should use check valve, need to automatically eliminate steam pipe and equipment of condensate, air and other cannot condensing gas, and to prevent the steam escape, should choose drain valve. In addition, when the medium is corrosive, good corrosion resistance materials should be selected.
(3) After the operation, installation, inspection (maintenance) repair of the valve, the operator should be able to correctly identify the valve direction, opening signs, indication signals, easy to timely and decisively deal with various emergency faults. At the same time, the selected valve type structure should be as far as possible cylinder sheet, installation, inspection (maintenance) repair convenient.
(4) Economy On the premise of meeting the normal use of process pipelines, valves with relatively low manufacturing cost and simple structure should be selected as far as possible to reduce the cost of the device, avoid the waste of valve raw materials and reduce the cost of valve installation and maintenance in the later stage.
Valve selection steps
Selection of valves generally follow the following steps,
1. Determine the working condition of the valve according to the use of the valve in the device or process pipeline. For example, working medium, working pressure and working temperature, etc.
2. Determine the sealing performance level of the valve according to the working medium, working environment and user requirements.
3. Determine the valve type and drive mode according to the purpose of the valve. Types such as Resilient butterfly valve, Rubber seated gate valve, Rubber seated gate valve, balance valve, etc. Driving mode such as worm wheel worm, electric, pneumatic, etc.
4. Choose according to the nominal parameters of the valve. The nominal pressure and nominal size of the valve shall be matched with the process pipe installed. The valve is installed in the process pipeline, so its working condition should be consistent with the design selection of the process pipeline. After the standard system and pipe nominal pressure are determined, the valve nominal pressure, nominal size and valve design and manufacturing standards can be determined. Some valves determine the nominal size of the valve according to the flow rate or discharge of the valve during the rated time of the medium.
5. Determine the connection form of the valve end surface and the pipe according to the actual operating conditions and the nominal size of the valve. Such as flange, welding, wafer or thread, etc.
6. Determine the structure and form of the valve type according to the installation position, installation space, and nominal size of the valve. Such as dark gate valve, rising stem gate valve, fixed ball valve, etc.
7. According to the characteristics of the medium, working pressure and working temperature, to correctly and reasonably select the valve.
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Post time: Oct-14-2023