What is a ball valve?

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Ball valve

Ball valve, GB/T21465-2008 "Valve term" is defined as: the opening and closing parts (ball) driven by the valve stem, and around the axis of the valve stem for rotational movement of the valve. It is mainly used to cut off or connect the medium in the pipeline, and it can also be used for the adjustment and control of fluids. The hard-sealed V-type ball valve has a strong shear between the V-shaped core and the hardened metal seat. Shear force, especially suitable for medium containing fiber, tiny solid particles, etc. The multi-pass ball valve can not only flexibly control the confluence, diversion, and flow direction of the medium on the pipeline, but also can close any one of the channels and connect the other two channels. This type of valve should generally be installed horizontally in the pipeline.

The birth and application of ball valves began in the 1950s. With the rapid development of science and technology, continuous improvement of the production process and product structure, it has rapidly developed into a major valve category in just 40 years. In the developed countries of the West, the use of ball valves is increasing year by year. In China, ball valves are widely used in petroleum refining, long-distance pipelines, chemicals, paper, pharmaceuticals, water conservancy, electricity, municipal, steel and other industries. The national economy plays a decisive role.

Edit this paragraph working principle Ball valve It has a rotation of 90 degrees of action, the plug body is a sphere, a circular through hole or channel through its axis. The ball valve is mainly used in the pipeline to cut off, distribute and change the flow direction of the medium. It only needs to rotate with 90 degrees of operation and a small rotating torque can close the tightness. The ball valve is most suitable for use as a switch or shut-off valve, but recent developments have designed the ball valve so that it has a throttling and control flow, such as a V-ball valve.

Edit this paragraph main features The main characteristics of the ball valve is its compact structure, reliable sealing, simple structure, easy maintenance, sealing surface and spherical surface often in the closed state, not easily eroded by the media, easy operation and maintenance, suitable for water, solvents, acids And general working media such as natural gas, but also suitable for working conditions of poor media, such as oxygen, hydrogen peroxide, methane and ethylene, have been widely used in various industries. The ball valve body can be integral or modular.

Edit this paragraph advantages 1. The fluid resistance is small, and the full diameter ball valve basically has no flow resistance.

2. Simple structure, small size, light weight.

3. Close and reliable. It has two sealing surfaces, and the current ball valve sealing surface material uses a wide range of plastics, good sealing, can achieve a complete seal. It has also been widely used in vacuum systems.

4. Easy to operate, fast opening and closing, as long as the rotation from 90 degrees from full open to fully closed, easy remote control.

5. Easy maintenance, ball valve structure is simple, the seal ring is generally active, removal and replacement are more convenient.

6. When fully open or fully closed, the sealing surfaces of the ball body and the valve seat are isolated from the medium. When the medium passes through, the sealing surface of the valve will not be eroded.

7. Wide range of applications, from small to several millimeters in diameter, up to a few meters in size, from high vacuum to high pressure can be applied.

8. Since the ball valve has wiping during opening and closing, it can be used in media with suspended solid particles.

Edit this paragraph ball valve installation and maintenance should pay attention to the following matters 1, to leave the valve handle rotation position.

2, can not be used for throttling.

3, ball valve with transmission mechanism should be installed upright.

Edit some of the ball valve parameters of this paragraph level 1, nominal pressure or pressure level: PN1.0-32.0MPa, ANSI CLASS 150-900, JIS10-20K

2, nominal diameter or diameter: DN6 ~ 900, NPS 1/4 ~ 36

3, connection: flange, butt welding, thread, socket welding, etc.

4, the applicable temperature: -196 Â°C ~ 540 Â°C

5, drive: manual, worm gear, pneumatic, electric, hydraulic, gas-liquid linkage, electro-hydraulic linkage

6. Body materials: WCB, ZG1Cr18Ni9Ti, ZG1Cr18Ni12Mo2Ti, CF8 (304), CF3 (304L), CF8M (316), CF3M (316L), Ti. The use of different materials can be applied to various media such as water, steam, oil, nitric acid, acetic acid, oxidizing medium, urea and so on.

Edit the model of the ball valve in this paragraph . Formulation Description Ball valve type code is Q. Add "D" before the low temperature ball valve and "B" before the heat ball valve.

Code number 0 1 2 3 4 5 6 7 8 9 Transmission method

turbine

pneumatic

Electric connection type internal thread male thread flange welding clip

Type Code Structure Ball Valve Q
Straight-through

Angle right angle

Floating

L type floating ball T type floating ball fixed ball

Handwheels, handles and wrench drives omit the code.

Sealing surface or lining material Code Sealing surface or lining material Code steel Alloy T Permeated Fluorine steel D Rubber X Cemented carbide Y Nylon plastic N lining J Fluorine plastic F Leaded lead Q Tin-base bearing alloy (Bay alloy) B Enamel C alloy The nominal pressure code for steel H-boron steel P is expressed in Arabic numerals, and its value is 10 times the nominal pressure in megapascals. Valves used in power station industry, when the maximum temperature of the medium exceeds 530Â°C, its value is 10 times of the working pressure value in megapascals.

Body Material Gray Cast Iron Ductile Iron Carbon Steel Alloy Steel (CrMo Steel) Stainless Steel Special Alloy Code Z Q WCB WC1 LCB LC3 WC6 WC9 C5/C12 Common CF8 CF8M CF3 CF3M M C C1 C2 C3 I6 I9 I5 P R1 R2 R3 R4
Ball valve performance specifications

Test item Test pressure (MPa) Test duration (S) Test temperature (oC) Test medium Shell test 150Lb, 1.6MPa 2.4 120 (DN â‰¤ 14") â‰¤ 52oC (room temperature) Water (may contain rust inhibitor) Kerosene or Other suitable medium whose viscosity is not greater than water 300Lb, 2.5, 4.0MPa 6.0 600Lb, 10.0MPa 15.0 900Lb, 15.0MPa 22.5 1500Lb, 25.0MPa 37.5 2500Lb, 42.0MPa 63.0 Low-pressure sealing test 150Lb, 1.6MPa 0.6 120 â‰¤ 52oC (room temperature) Air Or inert gas 300Lb, 2.5, 4.0MPa 600Lb, 10.0MPa 900Lb, 15.0MPa 1500Lb, 25.0MPa 2500Lb, 42.0MPa high pressure sealing test 150Lb, 1.6MPa 1.76 120 â‰¤ 52oC (normal temperature) water (may contain rust inhibitor) Kerosene or viscosity Other suitable medium not more than water 300Lb, 2.5, 4.0MPa 4.4 600Lb, 10.0MPa 11 900Lb, 15.0MPa 16.5 1500Lb, 25.0MPa 27.5 2500Lb, 42.0MPa 46.2 Main parts materials and properties

Body Stem Ball Seal Face Pad (Ring) Packing Operating Temperature Applicable Medium WCB 1Cr13 1Cr13 1Cr13 Stellite Body Material Flexible Graphite

Stainless steel + flexible graphite

08 Soft Steel

F304

F316 flexible graphite

Knotted Graphite -29~425oC Water and Steam Oil WC6 15CrMo 15CrMo -29~595oC WC9 25Cr2MoV 25Cr2MoV LCB 304 304 -46-345oC CF8 304 304 -196~600oC Section

Acid, alkali

Edit this paragraph classification and characteristics of ball valves are divided: floating ball ball valve, fixed ball ball valve, track ball valve, V-ball valve, ball valve, stainless steel ball valve, forged steel ball valve, ash ball valve, sulfur ball valve, three-way ball valve, pneumatic ball valve , electric ball valve, card sleeve ball valve, welded ball valve.

Classified by shell/body material, ball valves can be divided into:

1. Valves made of metal materials: such as carbon steel valves, alloy steel valves, stainless steel valves, cast iron valves, titanium alloy valves, Monel valves, copper alloy valves, aluminum alloy valves, and lead alloy valves.

2. Metal valve body lining valves: such as rubber lined valves, fluorine lined valves, lined lead valves, lined plastic valves, lined enamel valves.

3. Non-metallic valve: such as ceramic valves, glass valves, plastic valves.

There are many domestic manufacturers of ball valves, and most of the connection sizes are not uniform. Mainly divided into the following categories:

(1) There are many domestic manufacturers of ball valves, and most of the connection sizes are not uniform. Mainly divided into the following categories:

The JB/T2203-1999 ball valve structure length is a general class. At present, most domestic ball valve manufacturers are designed and produced according to this standard. Such as Shanghai Lianggong Valve Factory, Shanghai Liangzhong Valve Factory, Hangzhou Gate Valve Factory, Sichuan Guoda Valve Factory, Shanghai Valve Factory. However, this standard is not perfect and the specifications are not complete. It is recommended that design institutes and users be selected according to the standard. The ball valve manufacturer shall be designed and manufactured according to the standard.

Mainly divided into the following categories: 1. Floating ball valve

Floating ball valve

The ball of the ball valve is floating. Under the effect of medium pressure, the ball can produce a certain displacement and press on the sealing surface of the outlet end to ensure the sealing of the outlet end.

The structure of the floating ball valve is simple and the sealing is good. However, the load of the ball bearing the working medium is all transmitted to the outlet sealing ring. Therefore, it is necessary to consider whether the sealing ring material can withstand the working load of the ball medium when subjected to high pressure shock. Spheres may shift. This structure is generally used for low and medium pressure ball valves. 2, fixed ball valve

Fixed ball valve

The sphere of the ball valve is fixed and does not move after being pressed. The fixed ball ball valve has a floating valve seat. After the medium pressure, the valve seat moves and the seal ring is pressed against the ball to ensure the seal. Bearings are usually mounted on the upper and lower shafts of the ball, and the operating torque is small, suitable for high pressure and large diameter valves.

In order to reduce the operating torque of the ball valve and increase the reliability of the seal, oil seal ball valves have appeared in recent years. Special lubricants are injected between the sealing surfaces to form a layer of oil film, which enhances the sealing performance and reduces the operating torque. , It is more suitable for high pressure and large diameter ball valve. 3. The ball of the elastic ball valve (ie track ball valve) is elastic. The ball body and the valve seat seal ring are made of metal materials, and the specific pressure of the seal is large. The pressure of the medium itself cannot meet the requirements of the seal, and external force must be applied. This valve is suitable for high temperature and high pressure media.

The elastic ball is to open a flexible groove at the lower end of the inner wall of the ball to obtain elasticity. When closing the channel, use the wedge head of the valve stem to make the ball expand and seal with the valve seat. Loosen the wedge head before turning the ball, the ball will return to its original shape, so that there is a small gap between the ball and the valve seat, which can reduce the friction and operating torque of the sealing surface. 4ã€V type ball valve

V type ball valve

This type of ball valve is a fixed ball valve, also a single valve seat ball valve. The adjustment performance is the best among the ball valves. The flow characteristic is equal percentage, and the adjustable ratio is 100:1. Its V-shaped incision and metal valve seat have a shearing effect, especially suitable for media containing fiber, tiny solid particles, slurry. 5, three-way ball valve Three-way ball valve has T-type and L-type. T-type can make three orthogonal pipelines communicate with each other and cut off the third channel, which acts as a shunt and a confluence. The L type can only connect two pipes that are orthogonal to each other, and cannot simultaneously maintain the third pipe to communicate with each other, but only play a role in distribution.

Three way ball valve

Features

1. The three-way ball valve adopts an integrated structure in structure, and the sealing type of the four-face valve seat has few flange connections, high reliability, and the design is lightweight.

2. Three-way ball cores are divided into T-type and L-type, long service life, large circulation capacity, low resistance

3. The ball valve is divided into two types according to action: single action and double action. The single action type is characterized in that once the power source fails, the ball valve will be in the state required by the control system.

Edit this section 6, eccentric hemisphere valve 1, eccentric ball valve has the following advantages:

1. The fluid resistance is small, and its drag coefficient is equal to the length of the same length.

2. Simple structure, small size, light weight.

3. It is compact and reliable. At present, the sealing surface material of the ball valve is widely used with plastics and has good sealing performance. It has also been widely used in vacuum systems.

4. Easy to operate, fast opening and closing, as long as the rotation from 90 degrees from full open to fully closed, easy remote control.

5. Easy maintenance, ball valve structure is simple, the seal ring is generally active, removal and replacement are more convenient.

7. Wide range of applications, from small to several millimeters in diameter, up to a few meters in size, from high vacuum to high pressure can be applied.

Edit this paragraph temperature and pressure limit nameplate shows the maximum operating pressure of the ball valve at the maximum and minimum operating temperature.

With PTFE or RTFE seats and seals, the operating temperatures of other types of seats and seals should be checked by the KI factory.

The valve's nominal pressure rating (PN) indicates the valve's maximum operating pressure at normal temperature conditions. (For example, PN4.0 indicates that the operating pressure is -40 Bar (4.0 MPa) at -290C to 380C.

Precautions for electric or pneumatic actuators refer to their corresponding instructions.

Edit this paragraph is suitable occasion Because the ball valve usually uses rubber, nylon and PTFE as the valve seat seal material, so its use temperature is limited by the valve seat seal material. The cut-off effect of the ball valve is achieved by the metal ball body under the action of the medium and pressed between the plastic valve seats (floating ball valve). Valve seat seals under a certain contact pressure, the local area occurred elastic deformation. This deformation can compensate for the manufacturing precision and surface roughness of the ball and ensure the sealing performance of the ball valve.

Because ball valve seat ring is usually made of plastic, so in the choice of ball valve structure and performance, to consider the ball valve fire resistance and fire prevention, especially in the petroleum, chemical, metallurgical and other sectors, in the flammable, explosive media The use of ball valves in the equipment and piping system should pay more attention to fire resistance and fire protection.

Normally, double-position adjustment, tight sealing performance, mud, wear, shrink channels, rapid opening/closing action (1/4 turn), high pressure cut-off (large pressure difference), low noise, cavitation and gasification, The ball valve is recommended for piping systems that leak to the atmosphere in small amounts, have low operating torque and have low fluid resistance.

Ball valves are also suitable for use in light piping, low pressure cut-off (small differential pressure), corrosive media systems. Ball valves can also be used in cryogenic (cryogenic) units and piping systems. Oxygen piping systems in the metallurgical industry require the use of strictly degreasing ball valves. When the main line in the oil pipeline and gas pipeline is to be buried underground, full-diameter welded ball valves are required. When required to have adjustment performance, a special structure ball valve with a V-shaped opening is required. In petroleum, petrochemical, chemical, power, and urban construction, metal-to-metal sealed ball valves can be used in piping systems operating at temperatures above 200 degrees.

Edit this section to install 1) Remove the protective cover on both sides of the flange, and rinse it with the valve fully opened.

2) Before the installation, the whole machine should be tested according to the specified signal (electricity or gas) (to prevent the use of performance due to vibration caused by transportation), and it can be installed on-line only after being qualified (wiring according to the circuit diagram of the electric actuator).

3) Before connecting to the pipeline, the remaining impurities in the clean pipeline must be flushed and removed (these materials may damage the valve seat and ball).

4) During the installation, please do not use the actuator part of the valve as lifting point to avoid damage to the actuator and accessories.

5) This type of valve should be installed in the horizontal or vertical direction of the pipeline.

6) The pipe near the installation point must not have any sag or be subjected to external forces. Pipeline supports or supports can be used to eliminate line deviation.

7) After connecting with the pipe, cross-lock the flange bolts with the specified torque.

Edit this paragraph operation and use 1) Before operation, make sure that the tubing and valves have been flushed.

2) The operation of the valve is driven by the input signal of the actuator. Rotation of the valve stem is completed: When the valve rotates forward by 1/4 turn (90Â°), the valve is shut off. When the valve is rotated 1/4 turn (90Â°) in reverse, the valve opens.

3) When the actuator direction indicator arrow is parallel to the pipeline, the valve is open; when the indicator arrow is perpendicular to the pipeline, the valve is closed.

The maintenance of this section has a long service life and maintenance-free period, and will depend on the following factors: normal working conditions, maintaining a harmonious temperature/pressure ratio, and reasonable corrosion data

note:

â— When the ball valve is closed, there is still pressurized fluid inside the valve body.

â—Relieve line pressure and keep valve in open position before repair

â— Disconnect power or gas source before maintenance

â—Disengage the actuator from the bracket before maintenance

â— Must first find out that the pressure on the upper and lower pipelines of the ball valve has been removed before demolition and decomposition

â— When disassembling and reassembling, care must be taken to prevent damage to the sealing surfaces of parts, especially non-metallic parts. Special tools should be used when removing O-rings.

â— The bolts on the flange must be tightened symmetrically, gradually and evenly during assembly.

â— The cleaning agent should be compatible with the rubber parts, plastic parts, metal parts and working media (such as gas) in the ball valve. When the working medium is gas, metal parts can be cleaned with gasoline (GB484-89). Non-metallic parts cleaned with pure water or alcohol

â€¢ Separated parts can be washed by dipping. Metal parts that still have undecomposed non-metallic parts can be cleaned with a clean, finely-cleaned silk cloth impregnated with detergent (to prevent the fibers from sticking to the parts). Remove any grease, dirt, glue, dust, etc. that adhere to the wall when cleaning.

â— The non-metallic parts should be taken out of the cleaning agent immediately after cleaning, and shall not be soaked for a long time

â—After cleaning, it must be cleaned after the wall-washing agent is volatilized (can be wiped with a silk cloth not immersed in detergent), but it must not be left for a long time, otherwise it will be rusted and contaminated by dust.

â— New parts need to be cleaned before assembly

â— Lubricate with grease. Grease should be compatible with ball valve metal materials, rubber parts, plastic parts and working media. When the working medium is gas, for example, special grease 221 can be used. Apply a thin layer of grease to the surface of the seal mounting groove. Apply a thin layer of grease to the rubber seal. Apply a thin layer of grease to the sealing and friction surfaces of the stem.

â— Assembly should not allow metal debris, fibers, grease (except for the specified use) dust and other impurities, foreign matter and other pollution, adhesion or stay on the surface of the part or into the cavity 1), filler re locking If there is a micro leak in the packing, the stem nut must be locked again.

Note: Do not lock too tight. Normally, lock 1/4 to 1 turn again. Leakage will stop. 2) Replace the seat and seal A) Disassemble

With the valve in a half-open position, flush and remove potentially hazardous substances inside and outside the valve body.

Close the ball valve, remove the connecting bolts and nuts on both flanges, and then completely remove the valve from the line.

Remove the drive unit in order - actuator, connecting bracket, lock washer, stem nut, butterfly shrapnel, Glam, wear plate, stem packing.

Remove the body cap attachment bolts and nuts, separate the bonnet from the valve body, and remove the bonnet gasket.

Make sure that the ball is in the "off" position, which can be easily removed from the valve body and then remove the valve seat.

Push the valve stem downwards through the hole in the valve body until it is completely removed. Then remove the O-ring and the under-stem filling.

Note: Be careful to avoid scratching the stem surface and the body packing gland seal.

B) Reassemble

Cleaning and Inspection For removing parts, it is strongly recommended to replace the seats and gaskets of the bonnet gaskets with spare parts packs.

Assemble in reverse order of disassembly.

With the specified torque, cross-lock the flange connection bolts.

Use the specified torque to lock the stem nut.

After installing the actuator, input the corresponding signal to rotate the valve core by rotating the valve stem to make the valve open and closed.

If possible, perform pressure seal testing and performance testing of the valve in accordance with the relevant standards before returning the piping.

1, principle

The opening and closing part of the ball valve is a ball, and the ball rotates around the center line of the valve body to reach a valve that opens and closes.

2, applicable places

Low-pressure, small-diameter pipelines are used to cut off water flow and change the distribution of water flow or places that need to be opened and closed quickly.

3, characteristics

1) Small flow resistance;

2) The structure is simple;

3), small size, light weight;

4) At present, the sealing surface material of the ball valve is made of plastic and has good sealing performance;

5) Easy to operate, quick opening and closing, convenient for remote control;

6), easy maintenance, seals are generally active, easy to remove and replace;

7) When fully open or fully closed, the sealing surfaces of the ball body and the valve seat are isolated from the medium, and the passage of the medium will not cause erosion of the valve sealing surface.

4, classification

1). Commonly used ball valves are divided into floating ball valves, fixed ball valves, and lifter ball valves according to their working principles.

2) Ball valves can be divided into straight-through, tri-type and right-angle types according to their position. The latter two ball valves are used to distribute media and change the direction of the media.

5, construction, installation points

1) The installation position, height, and direction of import and export must meet the design requirements and the connection should be firm and tight.

2) All types of manual valves installed on the insulation pipe shall not be downwards.

3) Before the valve is installed, a visual inspection must be performed. The nameplate of the valve shall comply with the provisions of the current national standard "General Valve Mark" GB 12220. For valves with a working pressure greater than 1.0 MPa and a shut-off effect on the main pipe, strength and tightness tests shall be carried out before installation. In the strength test, the test pressure is 1.5 times the nominal pressure, and the duration is not less than 5 minutes. The valve housing and the packing should have no leakage as qualified. For the tightness test, the test pressure is 1.1 times the nominal pressure; the test pressure shall meet the requirements of GB 50243 standard for the duration of the test, and no leakage of the valve sealing surface shall be qualified.

4) Install gaskets between the valve flange and the pipeline flange according to the piping design requirements.

5) The ball valve with transmission mechanism shall be installed in accordance with the product instructions.

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