Inverted Pressure Balance Lubricated Plug Valve

classification

Plug Valve

According to the form of the structure can be divided into compact plug valve, self-sealing plug valve, plug valve and oil type plug valve four. According to the channel form, can be divided into straight through plug valve, three-way plug valve and four-way plug valve. And a clamped plug valve.

Classification of plug valves by purpose includes: soft seal plug valves, oil lubricated hard seal plug valves, lifting plug valves, three-way and four-way plug valves.

Soft seal

Soft seal plug valve is often used for corrosive, toxic and high harmful media and other harsh environment, strictly prohibited leakage occasions, and the valve material will not form pollution to the medium occasions. The valve body can choose carbon steel, alloy steel and stainless steel according to the working medium.

Oil lubricated hard seal

Oil - lubricated hard - sealed plug valves can be divided into conventional oil - lubricated plug valves and pressure balance plug valves. Special grease is injected from the top of the plug body between the taper hole of the valve body and the plug body to form an oil film to reduce the opening and closing moment of the valve and improve the sealing and service life. Its working pressure can reach 64MPa, the highest working temperature can reach 325 degrees, the maximum diameter can reach 600mm.

lift

Lifting plug valve has a variety of structural forms, lifting plug valve can be divided into soft seal and hard seal according to the sealing surface material. The basic principle is to make the cock rise when it is opened, and then turn the cock 90 degrees to the valve fully open process can reduce the friction with the valve body sealing surface; When closing the valve, turn the cock 90 degrees to the closed position and then drop to contact the sealing surface of the valve body to achieve sealing.

Three way and four way

Three-way and four-way plug valves are suitable for changing the direction of medium flow or medium distribution in Shanghai installation. According to the requirements of the working conditions, soft sealing bushing or soft sealing, hard sealing lifting plug valve.

advantages

Plug Valve

1, cock valve for frequent operation, open and close quickly, light.

2, plug valve fluid resistance is small.

3, plug valve simple structure, relatively small volume, light weight, easy maintenance.

4. Good sealing performance.

5, not limited by the direction of installation, the flow of the media can be arbitrary.

6. No vibration and little noise.

channel

Plug Valve

It comes in many forms. The common straight through is mainly used to cut off the fluid. Three-way and four-way plug valves are suitable for the opening and closing of fluid reversing plug valves. The opening and closing part of the valve is a perforated cylinder that rotates around an axis perpendicular to the channel to achieve the purpose of opening and closing the channel.

Installation and maintenance

Plug Valve

In order to prevent damage to the plug valve and ensure that the full performance of the plug valve should be paid attention to the following four points:

1. Make sure the valve is open. Heat the pipe first. Transfer as much heat from the pipe to the plug valve as possible. Avoid extending the heating time of the plug valve itself.

2. Use gauze or wire brush to remove the pipe and cutting part, so that the metal surface is luminous. Steel velvet is not recommended.

3. First, cut the pipe along the vertical direction, trim and remove burrs, and measure the pipe diameter.

4. Apply flux to the outside of the pipe and inside of the welding hood. The flux must completely cover the welding surface. Use flux sparingly.

Selection principle

Plug Valve

According to the structure and design of the plug valve can achieve the function, can be selected according to the following principles.

(1) It is used to distribute the medium and change the flow direction of the medium, the working temperature is not higher than 300℃, the nominal pressure PN≤ 1.6mpa, the nominal size is not greater than 300mm, it is recommended to use the multi-channel plug valve.

(2) Milk, juice, beer and other food enterprises and pharmaceutical factories, such as equipment and pipelines, it is recommended to choose austenitic stainless steel, compact conical plug valve.

In the branch pipe, refining and cleaning equipment of oil field exploitation, natural gas field exploitation, pipeline transportation, the nominal pressure class shall not be greater than Class300, the nominal diameter shall not be greater than 300mm, it is recommended to use oil seal conical plug valve.

In the branch pipe, refining and cleaning equipment of oil field exploitation, natural gas exploitation and pipeline transportation, the nominal pressure level shall not be greater than Class7500, the nominal diameter shall not be greater than 900mm, and the working temperature shall not be higher than 340℃, it is recommended to use oil seal conical plug valve.

(5) In the large chemical industry, the pipeline and equipment containing corrosive media, the need to open or close faster occasions, based on nitric acid medium can choose ptFE sleeve seal conical plug valve; For acetic acid-based media, Crl8Nil 2M02Ti stainless steel with teflon sleeve seals the conical cock valve.

In the gas, natural gas, HVAC system pipeline and equipment, nominal size is not more than 200nm, it is appropriate to choose packing conical plug valve.