Lubricated Plug Valve
China lubricated plug valve manufacturer, factory and supplier, produce inverted pressure balance lubricated plug valve, cast steel,forged steel,stainless steel lubricated plug valve, high pressure balanced lubricated plug valve and customized lubricated plug valve.
Lubricated Plug valve is critical components of a pipe system that transfers liquids, gases, vapors, slurries, and other substances from one location to another. When the media to be transferred contains slightly abrasive particles, mostly a Lubricated Plug Valve is used. It is a quarter-turn valve, which is beneficial for rapid and frequent operation.
Generally, a lubricated plug valve has a cylinder or cone type shape that is rotated inside the valve housing to control fluid flow. In addition, the plug valves are frequently positioned horizontally in one or more hollow passages that facilitate the flow of the valve while it is open. The 2-port design with a closed and open state is the most common design of the plug valve.
Now that you have a basic understanding of the lubricated plug valve, let’s find out in detail what is a lubricated plug valve classification, how does it work, its unique features, benefits, and applications.
What Is A Lubricated Plug Valve?
A lubricated plug valve is used to decrease friction and sealing of the ports by using the lubricant generally consists of a base oil and viscosity improver that is injected under pressure between the face and the body seat in the plug.
In general, valve manufacturers suggest lubricants that are suited to the fluid process, and valves frequently have to reseal after just a few cycles and in certain circumstances after every cycle.
The tightly sealed seat with lubricating oil is meant to decrease friction between the valve body and the sealing surface of the plug. A layer of oil film between the valve body and the sealing surface of the plug cone confirms the tight seal and smoothens the open/close motion when high-pressure sealing oil is injected around the plug to form a high-pressure seal ring.
Lubricated Plug Valve Specification
Size Range : NPS 1/2 to NPS 56
Class Range : 150LB to 2500LB
Design Standard : API6D / API599
Fire Standard : API 6FA
End Connection : RF / Threaded / BW
Operation : Manual Lever / Pneumatic / Electrical
Pressure Rating : ANSI Class 150 to Class 2500
Temperature Range : -46°C to +450°C
Pressure Testing : API 598 / API 6D / EN 12266-1/ISO 5208
Lubricated Plug Valve Construction
Lubricated Plug valves consist of all the parts that are present in a conventional plug valve.
Body: The body is cast in place and carefully machined for optimal flow. The plug, which serves as a sealing part, is housed in the body. The body must contain provisions for connecting to the pipeline, fluid holding strength requirements, plug seating region, lubrication mechanism, and stem seal.
Plug: For leak resistance, the plug is carefully machined with a grinding finish to be matched with the body seat. Grooves are included to aid in lubricant and sealant. According to the need, several flow passages can be made available.
Cover: The cover is attached to the bottom of the body by studs and nuts. This cover is made to withstand a lot of pressure while still complementing the body’s surface.
Stem: The stem has a burnished surface for lower torque and adequate strength for smooth plug movement.
Gear Box: For smooth functioning, a quarter-turn gearbox of robust design is used. Wrench, Gear, and other operators are available.
Injector: Injectors are placed on the body to infuse lubricant into the body and to seal the stem in the event of an emergency.
Lubricant: The lubricant works as a structural component of the valve, as it offers a flexible and renewable seat. To achieve a seal, this removes the need for force fits and metal-to-metal distortable-seat connections. To avoid the damaging effect of the line fluid and to produce an impermeable seal around each body port, even under pressure, the lubricant must display adequate elasticity as well as protection against the solvents and chemicals. The lubrication coating also prevents corrosion on the metal surfaces between the plug and the body. The lubricant seal created by the lubricant flowing through a series of lubrication grooves that round each port helps to keep the necessary layer on the metal closure surfaces.
Types of Lubricated Plug Valve
Lubricated plug valve can be divided into conventional lubricated plug valve and pressure balanced plug valve. The special grease is injected from the top of the plug body between the valve cone hole and the plug body, forming an oil film to reduce the valve opening and closing torque, imcrease sealing and service life. The operating pressure can be up to 42MPa, with a maximum operating temperature of 325℃ and a maximum size of 600mm.
Conventional oil lubricated plug valve
A. For conventional metal seat lubricated plug valve, the installation position of the plug cone is positive. In order to reduce the friction between the valve body and the sealing surface of the plug, the valve generally uses the sealing structure of the sealing grease lubrication seat. The high-pressure sealing oil injected from the high-pressure oil nozzle forms a high-pressure sealing ring around the plug, that is, there is a layer of oil film between the valve body and the sealing surface of the plug cone, which can be sealed and lubricated, and easy to open and close.
B. In order to further reduce the opening and closing torque of the lubricated plug valve, usually the method of reducing the diameter of the plug is used, therefore the lubricated plug valve usually uses a rectangular flow path. This method increases the fluid resistance of the plug valve while reducing the opening and closing torque of the plug valve.
C. The sealing part of the plug cone is welded with STL alloy material or adopts surface hardening technology to enhance the wear and corrosion resistance of the sealing surface, and the service life is long.
D. The surface of the cock cone is finely ground to the mirror surface, and the sealing surface of the valve body is ground, which has a lower opening and closing torque.
Pressure balanced lubricated plug valve
In order to reduce the torque of conventional metal seat lubricated plug valves, pressure balanced lubricated plug valves are often used. In addition to the characteristics of conventional oil ubricated plug valves, the pressure balanced plug valves also have the following characteristics:
A. The plug cone of the pressure balanced lubricated plug valve is mounted in an inverted position. There is a check valve on the upper part of the plug cone. When the valve is closed, due to the difference in the upper and lower cut area of the plug cone, the injected high-pressure sealing oil causes the plug body to be lifted upwardly, so that the plug body and the valve sealing surface can be better sealed.
B. At the moment when the valve is opened, the pressure in the lower chamber of the valve body is balanced with the medium pressure in the pipeline. The high-pressure sealing oil in the upper chamber causes the plug body to be pushed downward, and a slight gap appears between the plug cone and the sealing surface of the valve body, the torque of the rotating plug body is effectively reduced.
C. In high temperature conditions, the thermal expansion of the plug can be absorbed by its rise and fall. Oil lubricated plug valve, although the use of oil lubrication can appropriately reduce the opening and closing torque, but it may form pollution of the medium. Therefore, the sealed lubricant is selected for the actual operating conditions.
How Does A Lubricated Plug Valve Work?
A lubricated plug valve constitutes a cavity in the center of the plug that runs down its axis. This cavity is blocked at the bottom and has a sealant-injection fitting at the top. The sealant is poured into the cavity, and a check valve located underneath the injection fitting stops the sealant from flowing backward. The sealant flows out of the center cavity through radial openings into lubricating grooves that run the length of the plug’s seating surface.
The lubricant substance must be compatible with the pipeline fluid. It should not degrade or be washed away by the flow medium since this might pollute the fluid and break the seal between the plug and the body, leading to leakage. Furthermore, the sealant employed must be able to resist the flow medium’s temperature.
Features Of Lubricated Plug Valve
The all-metal structure is common in lurbicated plug valve. The little gap surrounding the plug may enable leakage, and if the gap is further reduced, friction will occur, and the plug may become trapped inside the valve body. The lubricant also decreases the amount of effort needed to open or shut the valve, allowing the plug to move smoothly. It also protects the plug from corrosion.
Sealant supports in the formation of a renewing the seal between the plug and the body, preventing internal leaking. It also keeps the sitting surface from corroding. It also works as a lubricant, reducing the amount of force necessary to operate the valve. Lubricant pressure lifts the plug up from the seat for a brief period, making it easier to spin. Furthermore, the high pressure ensures that no sediments are trapped between the valve body and the plug.
Lubricants used in a plug valve are, in fact, plastic sealants. Therefore, it is critical to use an efficient sealant with qualities such as appropriate elasticity, tolerance from solvents and chemicals, and the capacity to establish an impermeable seal around each body component even when it’s under pressure. The lubrication layer also prevents corrosion on the metal surfaces between the plug and the body.
Lubricated plug valve is produced in a wide variety of sizes and are suitable for use in high-pressure & temperature services. They are available in different sizes ranging from half an inch to 24 inches in length and with pressure capacities of up to 6000 psi. They are available with steel or iron bodies. In some operating conditions, these valves are less prone to wear and provide superior corrosion resistance.
Lubricated Plug Valve Applications
These lubricated plug valve is considered to be high-maintenance plug valves; they are commonly employed in special applications. For example, lubricated plug valves work effectively in operations that use fluids containing slightly abrasive particles, such as polluted upstream applications, gas pipeline systems requiring bypass valves, and blow-down valves on valve stations and kicker valves.Some industries where Lubricated Plug valve is used:Pulp & Paper, Mining, for metal works.Wastewater management, Midstream transportation, Downstream processing, etc.
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( For corrisive medium )
- Port size：1/2'' ~ 16''( 15mm ~ 400mm)
- Pressure： Class 150 ~ Class 900
- Medium：Water,oil,steam,gas
- Temperature：-196～450℃
- Body material：WCB CF8 CF3 CF8M CF3M or others
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( Flange End, BW,SW,Thread End is optional )
- Port size：1/2'' ~ 16''( 15mm ~ 400mm)
- Pressure： Class 150 ~ Class 900
- Medium：Water,oil,steam,gas
- Temperature：-196～450℃
- Body material：WCB CF8 CF3 CF8M CF3M or others
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( Inverted pressure balance lubricated structure )
- Port size：1/2'' ~ 16''( 15mm ~ 400mm)
- Pressure： Class 150 ~ Class 900
- Medium：Water,oil,steam,gas
- Temperature：-40～450℃
- Body material：WCB CF8 CF3 CF8M CF3M or others
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( Full port self lubricated structure )
- Port size：1/2'' ~ 16''( 15mm ~ 400mm)
- Pressure： Class 150 ~ Class 900
- Medium：Water,oil,steam,gas
- Temperature：-40～450℃
- Body material：WCB CF8 CF3 CF8M CF3M or others
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( Inverted pressure balance structure )
- Port size：1/2'' ~ 16''( 15mm ~ 400mm)
- Pressure： Class 150 ~ Class 900
- Medium：Water,oil,steam,gas
- Temperature：-40～450℃
- Body material：WCB, LCB,LCC,CF8,CF8M,CF3,CF3M or other material
