(1) thread connecting valve
This connection is usually in and out of the valve at the end of the processed into cone tube or straight pipe threads, can make its connection to the cone tube, threaded nipple or piping. Because of this connection may appear larger leakage channel, so available sealants, seal or packing tape to plug the channel. If the body is material can be welding, but expansion coefficient difference, or the extent of change working temperature range is very large, thread connecting department must be honey seal welding. Threaded connection of valve is mainly in nominal pass after 50 mm of the valve. If size size is too big, connection of the department of installation and seal is very difficult.
In order to ease of installation and remove the thread connecting valve, the proper place in pipeline system is available for pipe joints. Nominal diameter in 50 mm the following valve can be used as a section of pipe tube fittings, the set of section of the thread will connect two parts together.
(2) flange connection valve
Flange connection of valve, its installation and remove all more convenient. But better than the thread connecting valve heavy, corresponding the price also price is high. So it is suitable for various sizes and pressure pipe connection. But, when the temperature more than 350 degrees, as the bolt, gaskets and flange is flabby, also obviously reduce bolt load, and to force a lot of flange connection may produce leakage.
(3) welding connection valve
This connection is applicable to all kinds of pressure and temperature, be in charge of the moment when using conditions, more reliable than flange connection. But welding connection of valve remove and reinstall all more difficult, so it can usually use limited to long-term reliable operation, or conditions of use by carving, high temperature of the occasion. Such as thermal power station, nuclear power engineering, ethylene project piping.
Nominal diameter in 50 mm the following welding welding socket valves usually has to carry the pipe by plane. Because socket welding socket and pipeline in between a gap, so that may by some medium corrosion crack and, at the same time, the vibration of the pipeline will make joint fatigue, thus socket welding use of certain limits.
In nominal diameter is bigger, use conditions by time, high temperature of the situation, the body is often used for welding groove, and at the same time, because of the case have juncture demand, must choose technical good welder to finish the work.