Three common methods of regulating valve (control valve) is installed in the pipe is the the screwed pipe thread end of the bolt fastening with gasket flange and welded connections.
1, screwed pipe thread
Screw-connecting terminal, commonly used in the small valve (control valve), and with better economy than the flange connection end. Usually specify the thread is on the body taper pipe the female threads NPT (national pipe thread). Engages them by matching the male thread and the pipe ends to form a metal to metal seal. This connection type is usually limited to a valve of no greater than 2 inches, not recommended for use in high temperature conditions. If you have to remove the valve from the pipeline, valve maintenance may be very complex, and constantly open flange joint or joint of the valve body to spin out of the pipe, the valve will not be able to take away.
2 bolts fastening with gasket flange
The flanged end of the valve can easily be removed from the pipeline, suitable for most of the adjusting valve (control valve) to whom the manufacture of the working pressure range. Flanged end can be used for the 0 ℃ from absolute to about 815 ℃ (1500 ° F) in the temperature range. They can be used all caliber adjusting valve (control valve). Most common flange connection of the end plane, convex and ring joints Flanged end.
Plane type allows matching method and clamping the whole area of contact between the flange gasket. This structure is commonly used for low pressure, cast iron and copper body valve flange stresses caused by the initial bolt connecting force can be reduced.
Convex flange has a circular convex surface, equal to the internal diameter of the valve opening, having an outer diameter slightly smaller than the circle diameter of the screw hole center. Convex processing concentric groove, in order to obtain a good seal and prevent the gasket is blown. This flange with a wide variety of gasket materials and flange material for up to a pressure of 6000 Psig (414 bar) and up to a maximum temperature of 815 ℃ (1500 ° F). This flange connection is usually the standard ANSI 250 cast iron body and all steel and alloy steel valve body connection.
Annular engaging surface flange looks like convex flange, apart from the opening concentric with the electric control valve on the convex surface cut out a U-shaped groove. The gasket with an elliptical or octagonal cross-section metal ring. When the flange bolt is tightened, the gasket is pressed into the U-shaped groove of the mating flange, to form a tight seal. The gasket is usually soft iron or Monel (Monel is a trademark of Inco Alloys International, Inc.), but you can use almost any metal. This is an excellent connection at a high pressure, can be used up to 15000 Psig (1034 bar) of pressure, but are generally not used in high temperature conditions. Only steel or alloy body specified only in the form of such a connection end.
3, the welding connection end
Welding connection end of the adjusting valve (control valve) are tight leak-proof in all pressures and temperatures, and the initial cost. By welding end of the valve from the pipeline disassembly more difficult, and significantly limited the material can be welded. Welding two forms: socket weld and butt weld end.
The preparation step is a socket weld connection end drilling in the valve at each end of an inner diameter slightly larger than the outer pipe diameter jack. Pipes slide into the set of holes in the sleeve hole and shaft shoulder butt, and then with the ribbon welding engaged with the valve. Pipe wall thickness, for a given caliber Socket Weld end Dimensions are the same. They are usually provided together with 2-inch valve. Welded connection end preparation step is to cut out a chamfer at each end of the valve with a similar chamfer in the piping on the match. Both ends of the valve and with the pipe butt, and coupled together with full penetration welding. Such connections can be used for all valve types, connected to the end of the preparation process will vary because of the pipe wall thickness, they are usually provided together with the 2-1/2 inch and larger diameter valves. Welding the valve into the pipeline, care must be taken to prevent heat conduction to the valve trim parts. Low temperature composite valve trim must be removed before welding.
Article explains:
Paper series site or of self-publish, the site post aims to deliver more information to the visitor.
2, involving work content, copyright and other issues, please contact site within 30 days, we will be the first time to make appropriate treatment! About copyright issues, please contact: 13515194999
3, Zhuanzhai this article please indicate from: Jiangyin City Oulei Si valve valve repair factory www.olschina.com
4 other links:
Valve repair valve repair valve repair equipment valve grinding machine imported valve repair power station valve repair control valve maintenance |
