How to choose pneumatic valve pneumatic valve and pipeline connection form

there are many types of pneumatic valve and pipeline connection form, one of the main thread, flange and welding connection.
。 Threaded connection
this kind of connection is often a pneumatic valve end processing of import and export into thread taper pipe or straight pipe, of screwing in taper pipe nipple or pipe. Because of this connection may appear larger leakage channel, so it can be used sealants, sealing adhesive tape or filler to plug the channel. If the pneumatic valve body material can be welded, seal welding can be performed after a threaded connection. If material is to allow the welded joint, but the expansion coefficient difference is very big, or job change range of temperature is larger, threaded connections must only seal welding, threaded connection of the pneumatic valve is mainly under the nominal diameter in mm of pneumatic valve. If size size is too big, installation and connection department seal is very difficult.
in order to easy to install and remove the threaded connection of the pneumatic valve, pipe joint in the proper position of piping system available. Nominal diameter in mm below the pneumatic valve pipe fittings, pipe socket for use as a pipe socket threads will connect the two together.
。 Flange connection
flange connection of the pneumatic valve, its installation and disassembly are convenient, but heavy than threaded connection, the corresponding price is also high. So can be applied to a variety of sizes and pressure pipe connection. However, when the temperature exceeds ℃, due to the creep relaxation, bolts, gaskets and flange can obviously reduce the load on the bolt, to force a lot of flange connection may occur leakage.
。 Welding connection
this connection is suitable for all kinds of pressure and temperature, under the condition of hard use, more reliable than the flange connection. But the pneumatic valve welding connection disassembly and difficult to install, so its use is limited to usually can run reliably for a long time, or the use of strict and high temperature occasion. Such as coal-fired power stations, nuclear power engineering, ethylene project on the pipeline.
nominal diameter in mm below the welding pneumatic valve usually with welding socket to carry on the plane of the pipeline. Because the socket welding forming gap between the pin and pipeline, thus has the potential to crack corrosion by some media, at the same time, the vibration of the pipeline can make the connection part fatigue, so the application of the socket welding by certain restrictions.
in nominal terms is larger, the use of harsh conditions, higher temperature, pneumatic valve body often USES the groove butt welding, at the same time, have strict requirements for weld.