Imported valves have the same connection methods as domestic valves. They must be connected to the pipeline. This method of connecting the valve to the pipeline is called the valve connection method.
1. Threaded connection
This kind of connection usually involves processing the inlet and outlet ends of the valve into a taper pipe thread, which is screwed into the taper pipe threaded joint or pipe. Since this connection may have a larger leakage channel, a sealant can be used. Seal tape or packing to block these channels. If the material of the valve body can be welded, sealing welding can also be performed after threaded connection. If the material of the connecting parts is allowed to be welded, but the coefficient of expansion is very different, or the working temperature has a large range of variation, the threaded connecting parts must be hermetically welded.
Threaded valves are mainly valves with a nominal diameter below 50mm. If the diameter is too large, the installation and sealing of the connection part will be very difficult.
In order to facilitate the installation and removal of threaded valves, pipe joints can be used at appropriate positions in the pipeline system. Valves with a nominal diameter of less than 50mm can use pipe sockets as pipe joints, and the thread of the pipe socket connects the two connected parts together.
Generally, threaded connections are often used for imported solenoid valves, imported pressure reducing valves, imported ball valves, imported gas pressure reducing valves, and imported internal threaded ball valves.
2. Flange connection
Flange-connected valves are easier to install and disassemble. But it is heavier than the threaded connection, and the corresponding price is higher. Therefore, it can be applied to pipe connections of various diameters and pressures. However, when the temperature exceeds 350°C, due to the creep and relaxation of the screw, gasket and flange, the load of the screw will be significantly reduced, and leakage may occur to the flange connection with a large force.
Flange connection is the most commonly used connection method for imported valves and can be used for almost all valves. Such as imported flanged ball valve, imported flanged butterfly valve, imported flanged check valve, imported flanged stop valve, etc.
3. Welding connection
This connection is suitable for various pressures and temperatures, and is more reliable than flange connections when used under harsher conditions. However, it is difficult to dismantle and reinstall the valve connected by welding, so its use is limited to the occasions that can usually operate reliably for a long time, or where the use conditions are harsh and the temperature is high. Such as thermal power stations, nuclear power projects. On the piping of the vinyl project.
Welded valves with nominal diameters below 50mm usually have welding sockets to accept flat-end pipes. Because the socket welding is in the travel gap between the socket and the pipe, it may cause the gap to be corroded by certain media, and the vibration of the colleague’s pipe will fatigue the connection part. Therefore, the use of socket welding is subject to certain restrictions.
When the nominal diameter is large, the use conditions are harsh, and the temperature is high, the valve body is often connected by groove butt welding, and at the same time, there are strict requirements on the welding seam.
Such as imported welded high pressure globe valve, welded high pressure check valve, imported welded high pressure ball valve and so on.
Wafer connection: especially that the valve body is a butterfly valve, which has many wafer connections; such as imported wafer butterfly valves, there are also check valves and ball valves for wafers, such as imported wafer check valves and imported wafer ball valves.
Ferrule connection: According to requirements, such a connection will be used, such as a gas pressure reducing valve, or an imported gas cylinder pressure reducing valve, and a pipe with an inlet and outlet ferrule 8 is required.
Clamp quick-installation connection; for example, the quick-installation clamp connection of imported sanitary butterfly valve, and the quick-installation clamp connection of imported sanitary ball valve.
Special vacuum flange connection for vacuum, such as vacuum quick release flange connection of imported vacuum ball valve, vacuum KF flange connection.
