There are many connection forms for flanged gate valves, among which threaded connection, flange connection and electric welding connection are important connection methods.
Threaded connection：
The threaded connection generally makes the top of the inlet and outlet of the flanged gate valve into a solid taper pipe thread or a cylindrical external thread, and tighten the threaded joint or pipe. However, threaded connections may leak and require the use of a sealing stopper material. If the material of the flanged gate valve can be welded, it can also be sealed welded. However, if the material expansion coefficient of the connected parts has a large difference or the temperature of the workpiece varies greatly, the threaded connection must be sealed and welded.
The flanged gate valve with threaded connection is suitable for flanged gate valves with a nominal size within DN50. When the nominal size is larger, it is difficult to install and seal the connection. To facilitate installation and disassembly, a three-way joint can be used. Flanged gate valves with a nominal size within DN50 can use a pipe socket as a tee joint, and the thread of the pipe socket connects the two parts of the connection.
Flange connection:
Flange-connected flanged gate valves are easy to install and disassemble, and are mainly suitable for pipe connections with larger diameters and higher pressures. However, leakage may occur when the temperature exceeds 350°C, so the price is higher.
Welding connection:
Electric welding welding connection is mainly suitable for more severe pressure and temperature conditions. It is difficult to disassemble and reassemble flanged gate valves connected by electric welding and welding. It is suitable for long-term reliable operation or places with high difficulty and high temperature, such as thermal power stations, nuclear technology projects, and butadiene project pipelines.
Welded welded flanged gate valves with nominal size within DN5 generally have welded sockets, which can undertake pipelines with planar ends, but the gap surface corrosion and fatigue problems need to be considered in socket welding applications. In places with large nominal size, high application difficulty and relatively high temperature, weld seam butt welding is generally used, and the welding is strictly managed. When ordering, the size of the pipe must be indicated so that the manufacturer can make the socket and welding groove according to the size.
