What are the types of general-purpose equipment valves?
Core Tip: Valves are the control components in fluid delivery systems. From the simplest shut-off valves to the various valves used in extremely complex automatic control systems, the variety and specifications are quite numerous. The common valves are threaded to the valve. Three types of flanged valves and welded connecting valves.
It is understood that the valve is a control component in the fluid delivery system, with functions of cut-off, regulation, diversion, anti-backflow, voltage regulation, shunt or overflow relief, etc. It is a widely used hardware mechanical device, which can be used to control air and water. , the flow of various types of fluids such as steam, various corrosive media, mud, oil, liquid metal and radioactive media. Valves for fluid control systems, from the simplest shut-off valves to the various valves used in extremely complex automatic control systems, come in a wide variety of sizes and specifications. The common valves are classified by connection.
(1) Threaded valve
This connection is usually made by machining the inlet and outlet of the valve into a taper or straight pipe thread that can be attached to a taper pipe joint or pipe. Sealants, sealing tapes or fillers can be used to block these channels due to the large leakage channels that may occur with such connections. If the material of the valve body is weldable, but the coefficient of expansion is very different, or the range of variation of the operating temperature is large, the threaded joint must be honey sealed. Threaded valves are primarily valves that pass nominally below 50 mm. If the diameter of the passage is too large, the attachment and sealing of the joint is very difficult.
In order to facilitate the installation and removal of the threaded valve, a fitting is available at the appropriate location in the piping system. Valves with a nominal diameter of 50 mm or less can be used as a pipe joint, and the threads of the pipe joint connect the two parts of the joint.
(2) flanged valve
Flanged valves are easy to install and remove. However, the valve is more cumbersome than the threaded connection, and the price is also high. Therefore, it is suitable for pipe connections of various diameters and pressures. However, when the temperature exceeds 350 degrees, the bolts, gaskets, and flanges become slack, which also significantly reduces the load on the bolts, and may cause leakage to the flanged joint with a large force.
(3) welded connecting valve
This connection is suitable for a wide range of pressures and temperatures and is more reliable than flanged connections when used under load conditions. However, the valve connection and reinstallation of the welded joint are difficult, so its use is limited to the long-term reliable operation, or the use of conditional load and high temperature. Such as thermal power stations, nuclear power engineering, and ethylene engineering pipelines.
Welded valves with a nominal diameter of less than 50 mm typically have welded sockets to receive the pipe at the end of the load. Since the socket welding forms a gap between the socket and the pipe, it is possible to cause the gap to be corroded by some media, and the vibration of the pipe may fatigue the joint portion, so the use of socket welding is limited.
In the case where the nominal diameter is large, the condition is used, and the temperature is high, the valve body is often welded by the groove. At the same time, the weld seam has the original requirements, and the skilled welder must be used to complete the work.
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