Introduction Of Plug Valve
1.Summary
Cock of simple structure, switch quickly, fluid small resistance, quarter-turn operation. In an emergency, accidents can rapidly connect piping or cut off. Compared with the gate, globe valves, operating more flexible, switch more quickly. A cock is the plug hole as open-close part, body with stem rotation, to realize on-off movement.ball. The small pack-less cock, also known as "test". Cock of body for more than the cone (also), and the cylinder valve cone hole surface with seal components.
2.Soft-sealing plug valve
Soft sealing plug valve is used to corrosive, poisonous and high hazard medium harsh environment, strictly forbidden, and the leakage of medium valve material form of pollution. The body can choose according to the working medium carbon steel, alloy steel and stainless steel material.
A. can be used according to the working medium temperature and F46 by F4, PO, PVDF, PP, PE etc self-lubricating materials bushing, lubrication, work in the whole process of seal small friction coefficient, body work, service life is long.
B. the window design and export valve sealing structure, double ways for groove in the spinning process, the tc between the seal of the sealing pressure in a gradual change, to open or sexual position until the seal, produce enough pressure, seal reach zero leakage.
C double ring grooves way can make bushing firmly in the body does not produce displacement, and can absorb due to temperature change bushing of trace, bushing and deformation of the friction between the cock, has produced powerful automatic cleaning function, improve the service life of sealing.
D. piston top unique design, the lip seal using a soft seal diaphragm and metal material and diaphragm seal gasket combination can adjust the sealing between than the plug, and can ensure the flexible rotation, outlet and the seal of flange connection.
E. suitable for high scouring the gas-solid. The liquid-solid phase medium. Such as PVC, urea, this anhydride, caustic soda, or external leakage requirements of high, medium, such as absolute phosgene etc.
F. two-way flow, medium can be installed direction is unlimited, on-line maintenance, use more convenient
G. unique design can prevent electrostatic, fire safety, the use of security.
3.Oiling hard sealing plug valve
Oil lubrication hard sealing plug valves can be classified into regular oil lubrication cock and pressure balance cock. Special grease from the top injection valve cone and plug, formed between oil film to minimize valve open torque, improve sealing and long service life. Its working pressure can reach the highest 64MPa, working temperature reaches 325 °, the biggest diameter can reach 600mm.
1, conventional oil lubrication cock
A conventional hard sealing plug valve cone, the cock of the installation for installing. In order to reduce the friction and plug valve seal, the valve seat sealing grease generally adopted the sealing structure. Tip injection pressure oil from the oil, in high pressure formation pressure sealing ring around the cock, cock cone between body and a layer of oil seal, can close and lubrication, easy opening and closing.
B. in order to further reduce the open-close force plug valve, usually by reducing cock out, therefore, the diameter of the method using rectangular passage cock usually, this method in reducing cock on-off torque, increase the cock of the fluid resistance
C. cocks taper sealing parts hardfacing alloys or using the STL surface hardening technology, enhance the sealing surface resistance to abrasion and corrosion resistance and long service life
D. cock of the cone to mirror surface finishing grinding, polishing, sealing and body with lower hoist torque.
2, pressure balance cock
In order to reduce the conventional hard sealing plug valves torque, often USES pressure balance cock. Pressure balance cock besides conventional oil lubrication cock characteristic, and the following features:
A. pressure balance the cock taper plug valve installation for inversion. The upper one cone cock stop-check valves.
When the valve is in the closed because of the poor XiaJie cone cock, the pressure seal oil injection by up to plug the lifting force body, make the body and sealing plug valve can better seal.
B. in the valve body, the pressure piping with subarachnoid cavity pressure balance of media, the pressure on the seal oil make stuffed body by cone, and make the cock thrust and the tiny gaps between appear, rotating plug the body will reduce torque. Also can protect seal.
C) in high temperature condition, the cock of the expansion can pass to absorb, avoid seal wedge.
Oil lubrication hard sealing plug valves, although using oil lubrication can reduce open torque, but it is likely to medium pollution. Therefore according to actual condition choose seal lubricants.
4.Elevated plug valve
Ascension type plug valves have various forms of structure, sealing plug valve type according to the material into soft sealing and hard sealing two kinds. The basic principle for opening up, the cock again to cock 90 degrees to the valve is fully open turning process can reduce the friction with the body sealing, Close valve to cock rotating 90 ° to shut down and body position after sealing contact to seal.
1, double seal ascension type plug valves
Double seal ascension type plug valves for soft sealing structure. Cock body for three board into cylindrical plug on both sides of the plate, enchase rubber sealing, cylindrical wedgeplug.
Open valve transmission mechanism, to cock up on both sides, make curl board combined sealing plug valve body and, after driving plug from body rotates 90 degrees to the valve is fully open position.
Close valve driving mechanism which plug body rotation 90 ° to the closed position, then push down, on both sides of the body of plug and body bottom plate after contact with no longer moves, continue to decline, through the wedgeplug push on both sides of the plate are inclined to move, the import and export of soft sealing side plate after contact with body sealing by compression and seal.
Double sealing plug valve lift has double block and discharge valves in function, with pressure balance device, in order to prevent the system anomaly, and can reduce the shape-change valve open. Instantly Due to the sealing ring is compressed metal surface contact, valve protection function. The valve can be very convenient in maintenance, the body from the line, under the situation of disassembly by removing the body bottom cover can take on both sides of the plate from valve body out of change. Therefore also widely used in petroleum, natural gas, metallurgy, mining, coal gas engineering, light textile, ships dock, food and environmental protection water treatment and other industries to adjust, open pipeline flow.
2 and hard sealing plug valve lift
Metal hard seal ascension type plug valve seat sealing side, the valve can be sealed by the use of the flow direction of medium. Metal hard seal body ascension type plug valve closed, but through the handwheel and stem seal of seat, through increasing pressure sealing pressure, can make the cock has better sealing performance. Seat sealing convex, easy cleaning, sealing seal to stockpile media, or solid particles. The device used in chemical industry solid temperature occasions. Hard sealing structure of ascension type plug valves are various, common have two kinds.
A. the handwheel grip type plug valve type, working principle, make up for the open valves and cock. Close to turn the handle to cock rotating 90 degrees to the closed position, then turn the handwheel to cock transmission device to seal decline.
The valve to open process and seat cock, so the valve from the open-close very easily, sealing and in open or closed process to scratch and valve life long. But using handle small drive moment, so using nominal size is usually valve. The handwheel grip lift-out cock compact structure, small volume, low resistance.
B. mechanical transmission cross conveyor cock, working principle for transmission device: open the valve stem threads that turns up. Plug body, Cock and the driver turns cocks from after 90 to full valve opens. Closing to cock first rotating device after 90 degrees to the closed position, cock, not driving after turning down to cock thread, and the body sealing contact to seal.
Mechanical transmission mechanism can cross connection cylinder, electric equipment, hydraulic system of remote control.
Mechanical conveyor cock cross transmission device drivers, solve the input torque limit, lack of large diameter and valves to high stress direction.
Mechanical conveyor cock cross transmission channel and the cock of the pipe diameter, fluid resistance is small, easy cleaning. In oil and gas pipeline length of development is more and more big.
5.Three-way and four-way type plug valve
Three and four general cock applies to Shanghai engineering equipment, change the direction of medium flow distribution or medium. According to the requirements of the service condition, can choose soft sealing bushing or soft seal, hard sealing plug valve lift.
