Detailed Explanation of Connection and Installation Methods for Electric Eccentric Half Ball Valves
Electric eccentric semi-ball valves are widely used in petroleum, chemical industry, electric power, steel, papermaking, pharmaceuticals, food, textile and other industries.
What are the commonly used connection methods for electric eccentric semi-ball valves?
1. Welding method
This type of connection is suitable for various pressures and temperatures, and is more reliable than flange connections when used under higher load conditions. However, it is difficult to disassemble and reinstall welded valves, so its use is limited to situations where it can usually operate reliably for a long time, or where the operating conditions are severe and the temperature is high. Such as on the pipelines of thermal power plants, nuclear energy projects, and ethylene projects. Welded valves with a nominal diameter of less than 50mm usually have a welding socket to accept the pipe at the load plane end.
Since socket welding forms a gap between the socket and the pipe, the gap may be corroded by certain media. At the same time, the vibration of the pipe will fatigue the connection part, so the use of socket welding is subject to certain restrictions. In situations where the nominal diameter is large, the operating conditions are severe, and the temperature is high, the valve body is often grooved butt welded. At the same time, there are original requirements for the welding seam, and welders with excellent skills must be selected to complete this work.
2. Flange connection
Flange-connected valves are more convenient to install and disassemble. However, it is bulkier than threaded valves, and the corresponding price is also higher. Therefore, it is suitable for pipe connections of various diameters and pressures. However, when the temperature exceeds 350 degrees, as the bolts, gaskets and flanges become loose, the load of the bolts is also significantly reduced, and leakage may occur in flange connections that are subject to great stress.
3. Threaded connection
This kind of connection usually processes the inlet and outlet ends of the valve into tapered pipe or straight pipe threads, which can be connected to tapered pipe thread joints or pipelines. Because this type of connection can have large leak channels, these channels can be plugged with sealant, sealing tape, or filler. If the material of the valve body can be welded, but the expansion coefficient is very different, or the operating temperature changes within a large range, the threaded connection must be honey-sealed and welded. Threaded valves are mainly valves with nominal diameters below 50mm. If the diameter is too large, it will be difficult to install and seal the connection.
Preparation work before installation of electric eccentric semi-ball valve
1. Ensure that the pipeline at the installation position of the eccentric semi-ball valve is in a coaxial position, and the two flanges on the pipeline should remain parallel. Make sure that the pipeline can bear the weight of the ball valve itself. If it is found that the pipeline cannot bear the weight of the ball valve, provide corresponding supports for the pipeline before installation.
2. Confirm whether there are impurities, welding slag, etc. in the pipeline, and the pipeline must be purged clean. Check the nameplate of the electric eccentric semi-ball valve, fully open and close the ball valve several times to confirm that the valve can operate normally, and then comprehensively inspect all details of the valve to ensure that the valve is intact.
3. Remove the protective covers at both ends of the valve, check whether the valve body is clean, and clean the valve body cavity. Since the sealing surface of the ball valve is spherical, even small debris may cause damage to the sealing surface.
Installation of electric eccentric semi-ball valve
1. Any section of the ball valve can be installed at the upstream end. The handle ball valve can be installed at any position in the pipeline. If the ball valve is equipped with an actuator (such as a gearbox, electro-pneumatic actuator), it must be installed vertically, with the valve inlet and outlet in a horizontal position.
2. Install a sealing gasket between the ball valve flange and the pipeline flange according to the pipeline design requirements. The bolts on the flange must be tightened symmetrically, successively and evenly.
3. If the eccentric semi-ball valve adopts pneumatic or electric actuators, complete the installation of air source and power supply according to the instructions.
Inspection after installation of electric eccentric semi-ball valve
After the electric eccentric semi-ball valve is installed, start the ball valve to open and close several times. The movement should be flexible, the force should be uniform, and the ball valve should work normally. According to the pipeline pressure design requirements, the sealing performance of the joint surface of the ball valve and the pipeline flange is tested after the pressure is released.
