Key Tips for Selecting and Installing Flanged Control Valves
I. Key points for selecting flanged control valves
Clarify the purpose and working conditions of the valve
Before selecting the valve, you first need to clarify the purpose of the valve in the equipment or device and determine the working conditions of the valve, including the properties of the applicable medium, working pressure, working temperature and operation control method. This information is the basis for selecting the valve type and material.
Select the type of valve
Choose the appropriate valve type according to the process requirements and fluid characteristics. Commonly used flanged valves include gate valves, stop valves, ball valves, butterfly valves, etc. For example, gate valves are suitable for occasions that require good sealing performance, while ball valves are suitable for occasions that require fast opening and closing.
Determine the flange connection form
Flange connection is a common connection method for flanged control valves, and its selection should be determined according to the pipeline pressure level, medium characteristics and use requirements. Flange-connected valves are easy to install and disassemble, and are suitable for pipeline connections of various diameters and pressures.
Select the material of the valve
The material selection of the valve shell, internal parts and sealing surface should comprehensively consider the physical properties (temperature, pressure) and chemical properties (corrosiveness) of the working medium, as well as the cleanliness of the medium (presence of solid particles). Common valve body materials include cast iron, carbon steel and stainless steel, and sealing ring materials include rubber, copper, alloy steel, etc.
Determine other parameters
In addition to the above points, it is also necessary to determine the flow rate and pressure level of the fluid flowing through the valve, and use existing information (such as valve product catalogs, valve product samples, etc.) to select the appropriate valve.
II. Key points for the installation of flanged control valves
Follow the design documents and national standards
The installation of control valves should be carried out strictly in accordance with the provisions of the design drawings and design documents, and at the same time follow the relevant national standards, such as the quality inspection and evaluation standards for building installation projects, and the construction and acceptance specifications for industrial automation instruments.
Select a suitable installation location and orientation
The installation location should have sufficient operating space for easy installation, operation and maintenance. The installation orientation should make the actuator of the control valve on the upper part of the regulating mechanism, and avoid installation in places with vibration, humidity, mechanical damage, strong electromagnetic interference, high temperature, drastic temperature changes and corrosive gases.
Pay attention to the details of flange connection
When making flange connection, ensure that the verticality of the flange surface on the pipe and the center line of the pipe and the error of the flange bolt hole are within the allowable range. The flange surface should be free of damage and scratches and kept clean. When tightening the bolts, tighten them in a symmetrical and cross-direction sequence to avoid uneven force.
Consider the flow direction of the fluid and the connection of accessories
The flow direction of the fluid in the control valve should be consistent with the arrow marked on the control valve body. At the same time, attention should be paid to the connection of accessories such as the discharge valve, vent valve, and drain valve to ensure that the pressure before and after the valve is discharged before disassembling the control valve.
Installation of actuators and valve positioners
The connection between the actuator and the control valve body should be firm and reliable, and the connecting rod and mechanical moving parts should be flexible and not loose. The installation of the valve positioner should ensure that the feedback signal can correctly and timely reflect the valve position signal and changes.
Testing and Acceptance
After the installation is completed, the control valve and its accessories should be tested to ensure that they meet the requirements of the technical annex of the contract. At the same time, the contracting party should be required to provide material analysis reports, leakage test reports and other documents of the key components of the control valve for inspection and review.
In summary, the selection and installation of flanged control valves is a complex process involving many factors. By clarifying the purpose and working conditions of the valve, selecting the appropriate valve type and material, paying attention to the details of the flange connection, and implementing strict testing and acceptance procedures, the stable operation and reliable performance of flanged control valves in industrial production processes can be ensured.