News Archives

Basic knowledge of valve

August 18, 2020

A valve is a device used to control the direction, pressure and flow of fluid in a fluid system. A valve is a device that allows the medium (liquid, gas, powder) in the piping and equipment to flow or stop and can control its flow.

lug type butterfly valve, ductile iron, center lined,

The valve is a control component in the pipeline fluid conveying system. It is used to change the passage section and the flow direction of the medium. It has the functions of diversion, cutoff, throttling, check, diversion or overflow pressure relief. Valves used for fluid control, from the simplest shut-off valves to the various valves used in extremely complex automatic control systems, have a wide range of varieties and specifications. The nominal diameter of the valve ranges from extremely small instrument valves to large diameters of 10m. Valves for industrial pipelines. The valve can be used to control the flow of various types of fluids such as water, steam, oil, gas, mud, various corrosive media, liquid metals, and radioactive fluids. The working pressure of the valve can be from 0.0013MPa to 1000MPa ultra-high pressure and working temperature From the ultra-low temperature of -270℃ to the high temperature of 1430℃. The valve can be controlled by a variety of transmission methods, such as manual, electric, hydraulic, pneumatic, turbine, electromagnetic, electromagnetic hydraulic,

Electro-hydraulic, pneumatic-hydraulic, spur gear, bevel gear drive, etc.; it can act according to predetermined requirements under the action of pressure, temperature or other forms of sensing signals, or simply open or close without relying on sensing signals , The valve relies on the drive or automatic mechanism to make the opening and closing parts move up, down, sliding, swinging or rotating, thereby changing the size of the flow channel area to achieve its control function.

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

What are the accessories for pneumatic valves?

August 18, 2020

Pneumatic valves have the advantages of fast switching and low price. Correct selection of pneumatic valves requires the use and characteristics of related accessories to achieve stable performance and long service life. In addition to improving the quality of the valve, it is also The matching of accessories is also very important. Here, I will introduce the characteristics and uses of several main accessories of pneumatic valves.

pnumatic actuator for butterfly valve

Accessory 1: Solenoid valve

The exact name of the solenoid valve should be the electromagnetic directional valve. The solenoid valve equipped with pneumatic valve mainly has two five-way and two-way three-way. The two-position five-way solenoid valve is usually used in conjunction with a double-acting pneumatic actuator, and the two-position three-way solenoid valve is used in conjunction with a single-acting pneumatic actuator. The pneumatic valve is used to switch the air intake and the air source through the solenoid valve. The air is discharged to achieve the function of opening and closing the valve. The solenoid valve has a single electric control solenoid valve and a double electric control solenoid valve. Explosion-proof solenoid valves should be used in special flammable and explosive occasions.

5 double-eccentric-butterfly-valve-2

Accessory 2: Limit switch

The limit switch is a long-distance transmission signal for opening or closing of the valve. The explosion-proof limit switch should be used in special flammable and explosive occasions.

Accessories 3: Air source treatment triple

Air source treatment triples include pressure reducer, filter, and oil mist device. The pressure reducer is mainly used to stabilize the air source and can adjust the pressure of the cylinder. The greater the pressure, the faster the valve opening and closing speed, which increases the friction of the valve and easily damages the sealing ring, thus affecting the service life of the valve; filter and The lubricator can filter the impurities in the air, clean and automatically add lubricant to the cylinder. Therefore, we recommend that the user is equipped with a three-piece valve for each valve, so that the pneumatic actuator can be better maintained and used for a longer time.

Fasteners, fillers and gasket materials of valves

August 17, 2020

There are many other valves parts and 1. Fastener material of valves:

valve bonnets

Fasteners mainly include bolts, studs and nuts. The fastener directly bears the pressure on the valve, which plays an important role in preventing the outflow of the medium. Therefore, the selected material must ensure sufficient strength and impact toughness at the operating temperature. When selecting fastener materials according to medium pressure and temperature, you can choose according to Table 5-1. Name Nominal Pressure Pg (Mpa) Medium Temperature (℃) 300 350 400 425 450 530 Bolt Stud Bolt 1.6-2.5 A3 35 30CrMoA _4.0-10.0 35 35CrMoA 25Cr2MoVA16.0-20.0 30CrMoA 35CrMoA 25Cr2MoVA Nut 1.6-2.5 A3 30 35 _4.0-10.0 30 35 35CrMoA16.0-20.2 35 35CrMoA Table 5-1 must undergo heat treatment when selecting alloy steel materials. When there are special corrosion resistance requirements for tight-return parts, stainless and acid-resistant steels such as Cr17Ni2, 2Cr13, 1Cr18Ni9 can be selected.

2. Filler material of valves:
On the valve, the packing is used to fill the space of the valve cover packing chamber to prevent the medium from leaking through the valve stem and the valve cover packing chamber space.

1. Requirements for packing 1) Good corrosion resistance, the packing must be able to withstand the corrosion of the medium in contact with the medium. 2) The sealing is good, and the packing will not leak under the action of the medium and working temperature. 3) The friction coefficient is small to reduce the friction torque between the valve stem and the packing.

2. Types of fillers Fillers can be divided into two types: soft fillers and hard fillers: 1) Soft fillers: are made of plant materials, namely hemp, flax, cotton, jute, etc., or are made of minerals, that is, asbestos fibers, or Wire ropes braided by asbestos fibers with metal wires inside and graphite powder coated on the outside, as well as pressed shaped fillers, and flexible graphite filler materials newly developed in recent years. Plant-based packing is cheaper, and is often used for low-pressure valves below 100°C; mineral packing can be used for valves with 450-500°C. In recent years, the structure of using rubber O-rings as packing has been gradually promoted, but the temperature of the medium is generally limited to below 60℃. The packing on the high temperature and high pressure valve is also compacted with pure asbestos and flake graphite powder. 2) Hard filler: that is, filler made of metal or metal mixed with asbestos and graphite and filler formed by pressing and sintering of polytetrafluoroethylene. Metal filler is used less.

3. The choice of packing The packing should be selected according to the medium, temperature and pressure. Commonly used materials are as follows: 1) Oil-impregnated asbestos rope, which can be selected according to Table 5-2. 2) Rubber asbestos rope: can be selected according to Table 5-3. 3) Graphite asbestos rope: The asbestos rope is coated with graphite powder. The usable temperature is above 450℃ and the pressure can reach 16Mpa. It is generally suitable for high-pressure steam. Lately, it gradually adopts the compression-shaped packing, which is placed in a single circle and has good sealing performance. 4) Polytetrafluoroethylene: This is a filler that is currently widely used. Especially suitable for corrosive media, but the temperature should not exceed 200℃. It is generally made by pressing or bar stock, and its shape is shown in Figure 5-1. Name, brand, shape and specification (diameter or square side length) Applicable ultimate pressure kgf/cm2 Applicable ultimate temperature (℃) Purpose Oil-impregnated asbestos rope YS450 F 3.4.5.6.8.10 13.16.19.22.25 60 450 For water vapor, air, petroleum Product Y 5.6.8.10.13 16.19.22.25N 3.5.6.8.10.13 16.19.22.25 YS350 F, Y, N 3.5.6.8.10.13 16.19.22.25. 45 350 YS250 F, Y, N 3.5.6.8.10.13. 16.19.22.25 45 250 Table 5-2 Note: The shape code F means square, through the core or one to multi-layer braid; Y means round, with a twisted core in the middle, and one to multi-layer braid on the outside; N means twisted. Name, grade and specification (straight formula or square side length) Applicable ultimate pressure kgf/cm2 Applicable ultimate temperature (℃) Purpose Rubber asbestos packing XS450 3.4.5.6.8 10.13.16.19 22.25.28 60 450 Used for steam and petroleum products XS350 45 350 XS250 45 250 Table 5-3

3. Gasket material:
The gasket is used to fill all the unevenness between the two joint surfaces (such as the sealing surface between the valve body and the valve cover) to prevent the medium from leaking between the joint surfaces. 1. Requirements for gaskets The gasket material has a certain degree of elasticity, plasticity and sufficient strength at working temperature to ensure sealing. At the same time, it must have good corrosion resistance. 2. Types and selection of gasket materials Gaskets can be divided into two types: soft and hard. The soft is generally non-metallic materials, such as cardboard, rubber, asbestos rubber sheet, and polytetrafluoroethylene. Hardness is generally metal material or metal-coated asbestos, metal and asbestos entangled, etc. There are many shapes of gaskets, including flat, round, oval, tooth-shaped, lens-shaped and other special shapes. Metal gaskets are generally made of 08, 10, 20 high-quality carbon steel and 1Cr13, 1Cr18Ni9 stainless steel, which require high machining accuracy and surface finish, and are suitable for high temperature and high pressure valves. Non-metallic gasket materials generally have good plasticity and can be sealed with less pressure. Suitable for low temperature and low pressure valves. The gasket material can be selected according to Table 5-4. Gasket material medium application range Pressure (Mpa) Temperature (℃) Thick cardboard water, oil ≤10 40 Oil-immersed cardboard water, oil ≤10 40 Rubber sheet water, air ≤6 50 Asbestos board steam, gas ≤6 450 poly Tetrafluoroethylene corrosive medium≤25 200 Rubber asbestos board XB-450 Water vapor, air, gas≤60 450XB-350 Water vapor, air, gas≤40 350XB-200 Water vapor, air, gas≤15 200 Oil-resistant rubber asbestos board oil Class 160 3008 steel and XB-450 filling steam 100 45008 steel and XB-350 filling steam 40 3501Cr13, 0Cr13 asbestos filling steam 100 60008 steel and oil-resistant rubber asbestos filling oil 100 350 copper water vapor, air 100 250 aluminum water vapor, air 64 35010 steel, 20 steel water steam, oil 200 4501Cr13 steam 200 5501Cr13Ni9 steam 200 600

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

What is the material of Bolts and nuts of Valve Stem?

August 17, 2020

Bolts and nuts material of valve stem:

bolts and nuts for butterfly valve

The stem nut directly bears the axial force of the stem during the opening and closing of the valve, so it must have a certain strength. At the same time, it and the valve stem are threaded transmission, which requires a small friction coefficient, no rust and avoid seizure.

1. Copper alloy Copper alloy has a small friction coefficient and does not rust. It is one of the commonly used materials. For low pressure valves with Pg<1.6Mpa, ZHMn58-2-2 cast brass can be used. ZQAL9-4 Wuxi bronze can be used for Pg16-6.4Mpa medium pressure valve. For high-pressure valves, ZHAL66-6-3-2 cast brass can be used.

2. Steel When the working conditions do not allow the use of copper alloys, high-quality carbon steels such as 35 and 40 can be selected, and stainless acid-resistant steels such as 2Cr13, 1Cr18Ni9, and Cr17Ni2 can be used. Working conditions are not allowed to refer to the following situations.

1. For electric valves, stem nuts with melon clutches need heat treatment to obtain high hardness or surface hardness.

2. When the working medium or the surrounding environment is not suitable for copper alloy, such as ammonia medium that corrodes copper. When selecting steel stem nuts, pay special attention to thread seizure.

Tianjin Tanghai Valve Manufacturing Co., Ltd. is one of the largest valve bolts and nuts manufacturers in China, main products are butterfly valves, check valves, gate valve and globe valves. Key words: butterfly valve, lug type butterfly valve, wafer type butterfly valve, U-type butterfly valve, double flange butterfly valve, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…)

What is the material of the butterfly valve stem?

August 17, 2020

Stem material classification:
During the opening and closing of the butterfly valve, the valve stem bears the forces of tension, pressure and

buttefly valve stem shaft parts (6)

torsion, and is in direct contact with the medium. At the same time, there is relative frictional movement with the packing. Therefore, the valve stem material must ensure that there is enough at the specified temperature Strength and impact toughness, a certain degree of corrosion resistance and scratch resistance, and good manufacturability. The commonly used stem materials are as follows.

1. When carbon steel is used in water and steam medium with low pressure and medium temperature not exceeding 300℃, A5 ordinary carbon steel is generally used. When used in water and steam medium with medium pressure and medium temperature not exceeding 450℃, 35 high-quality carbon steel is generally used.

2. When alloy steel is used for medium pressure and high pressure, and the medium temperature does not exceed 450 ℃ water, steam, petroleum and other media, 40Cr (chromium steel) is generally used. 38CrMoALA nitriding steel can be used when it is used in water, steam and other media with high pressure and medium temperature not exceeding 540℃. 25Cr2MoVA chromium molybdenum vanadium steel is generally used when used in high pressure steam medium with medium temperature not exceeding 570℃.

3. Stainless acid-resistant steel S is used for non-corrosive and weakly corrosive media with medium and high pressure and medium temperature not exceeding 450℃. 1Cr13, 2Cr13, 3Cr13 chromium stainless steel can be selected. When used in corrosive media, stainless acid-resistant steel such as Cr17Ni2, 1Cr18Ni9Ti, Cr18Ni12Mo2Ti, Cr18Ni12Mo3Ti, and PH15-7Mo precipitation hardening steel can be selected.

4. When heat-resistant steel is used for high-temperature valves whose medium temperature does not exceed 600℃, 4Cr10Si2Mo martensitic heat-resistant steel and 4Cr14Ni14W2Mo austenitic heat-resistant steel can be selected.

Tianjin Tanghai Valve Manufacturing Co., Ltd. is one of the largest valve stem/shaft manufacturers in China, main products are butterfly valves, check valves, gate valve and globe valves. Key words: butterfly valve, lug type butterfly valve, wafer type butterfly valve, U-type butterfly valve, double flange butterfly valve, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…)

What is the material of the main parts of the butterfly valve?-(2)

August 17, 2020

Selection of valve sealing material:

Sealing surface material: The sealing surface is the most critical working surface of the valve. The quality of the

marine valve seat

sealing surface is related to the service life of the valve. Generally, the sealing surface material should consider factors such as corrosion resistance, scratch resistance, erosion resistance, and oxidation resistance. Usually divided into two categories:

(1) Soft materials of butterfly valve:

Rubber (including nitrile rubber, fluorine rubber, etc.)
Plastics (polytetrafluoroethylene, nylon, etc.)

(2) Hard sealing material of butterfly valve:

Copper alloy (used for low pressure valves)
Chrome stainless steel (used for ordinary high and medium pressure valves)
Stellite alloy (used for high temperature and high pressure valves and strong corrosion valves)
Nickel-based alloy (used for corrosive media)

Tianjin Tanghai Valve Manufacturing Co., Ltd. is one of the largest butterfly valve manufacturers in China, main products are butterfly valves, check valves, gate valve and globe valves. Key words: butterfly valve, lug type butterfly valve, wafer type butterfly valve, U-type butterfly valve, double flange butterfly valve, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…)

What is the material of the main parts of the butterfly valve?-(1)

August 17, 2020

Selection of butterfly valve parts materials:
There are many materials for manufacturing butterfly valves, including ferrous and non-ferrous metals and their

16 U-type-flange-butterfly-vlave-body

alloys of different brands, and various non-metallic materials. The materials for manufacturing valve parts should be selected based on the following factors:

1. Pressure, temperature and characteristics of working medium.

2. The force of the part and its function in the valve structure.

3. It has better manufacturability.

4. If the above conditions are met, there must be a lower cost.

The material of the valve body, bonnet and disc (disc) The body, bonnet and gate (disc) are one of the main parts of the valve, which directly bear the pressure of the medium, and the material used must meet the “pressure and temperature rating of the valve” Provisions.

Commonly used material types for butterfly valves:

1. Gray cast iron: Gray cast iron is suitable for water, steam, air, gas, oil and other media with a nominal pressure of PN≤1.0MPa and a temperature of -10℃~200℃. The commonly used grades of gray cast iron are: HT200, HT250, HT300, HT350.

2. Malleable cast iron: Suitable for water, steam, air and oil media with a nominal pressure

17 center-line-butterfly-valve-plate-disc-parts-4

of PN≤2.5MPa and a temperature of -30~300℃. Commonly used grades are: KTH300-06, KTH330-08, KTH350-10.

3. Ductile iron: suitable for water, steam, air and oil with PN≤4.0MPa and temperature of -30~350℃. Commonly used grades are: QT400-15, QT450-10, QT500-7. In view of the current level of domestic technology, the plants are uneven, and users are often not easy to inspect. According to experience, it is recommended that PN≤2.5MPa, and the valve should be made of steel for safety.

4. Acid-resistant high-silicon ductile iron: suitable for corrosive media with nominal pressure PN≤0.25MPa and temperature below 120℃.

5. Carbon steel: suitable for water, steam, air, hydrogen, ammonia, nitrogen and petroleum products with a nominal pressure of PN≤32.0MPa and a temperature of -30~425℃. Commonly used grades are WC1, WCB, ZG25 and high-quality steel 20, 25, 30 and low-alloy structural steel 16Mn. Six, copper alloy: suitable for water, sea water, oxygen, air, oil and other media with PN ≤ 2.5MPa, and steam media with a temperature of -40 to 250 ℃, commonly used brands are ZGnSn10Zn2 (tin bronze), H62, Hpb59-1 (Brass), QAZ19-2, QA19-4 (aluminum bronze).

18 buttefly-valve-stem-shaft-parts-1

7. High temperature steel: suitable for steam and petroleum products with nominal pressure PN≤17.0MPA and temperature≤570℃. Commonly used grades are ZGCr5Mo, 1Cr5M0. ZG20CrMoV, ZG15Gr1Mo1V, 12CrMoV, WC6, WC9, etc. The specific selection must be in accordance with the valve pressure and temperature specifications. 8. Low temperature steel, suitable for nominal pressure PN≤6.4Mpa, temperature≥—196℃ ethylene, propylene, liquid natural gas, liquid nitrogen and other media, commonly used grades) ZG1Cr18Ni9, 0Cr18Ni9, 1Cr18Ni9Ti, ZG0Cr18Ni9.

9. Stainless acid-resistant steel, suitable for nitric acid, acetic acid and other media with nominal pressure PN≤6.4Mpa and temperature≤200℃. Commonly used grades are ZG0Cr18Ni9Ti, ZG0Cr18Ni10<nitric acid>, ZG0Cr18Ni12Mo2Ti, ZG1Cr18Ni12Mo2Ti<acid and urea>.

Strainer valve introduction and its features

August 17, 2020

STRAINER VALVE, also known as filter: a device for filtering pretreatment. The filter valve is the filter equipment necessary for the use of hydraulic control valves and precise and easy-to-clog mechanical products.

Strainer valve Introduction:
STRAINER VALVE, also known as filter: a device for filtering pretreatment. The filter valve is the filter equipment necessary for the use of hydraulic control valves and precise and easy-to-clog

15 Y-type-strainer-filter-valve-7

Y type strainer filter valve (11)

mechanical products. It is an indispensable device in the pipeline series that transports the medium. It is usually installed at the inlet of hydraulic control valves, pressure relief valves, pressure relief valves, fixed water level valves and other equipment to eliminate impurities in the medium and prevent particulate impurities from entering The channel causes wall plugs to protect the fittings on the equipment pipeline from wear and blockage. When cleaning is needed, just take out the detachable filter cartridge and reinstall it after treatment. Therefore, the use and maintenance are extremely convenient.

Features of filter valve:
The filter valve mesh adopts a stainless steel double-layer mesh structure, which is sturdy and durable. It has the characteristics of advanced structure, low flow resistance, and convenient sewage discharge. It can be used for water, steam, oil, nitric acid, urea, oxidizing media and other media. The mesh number of the filter screen should be set according to the user’s needs. Generally, the water network is 18-30 mesh, the ventilation network is 40-100 mesh, and the oil network is 100-480 mesh. The Y-type filter can also be combined with the telescopic joint to form a Y-type pull rod telescopic filter with adjustable installation length. The filter screen can be made according to user requirements.

Filter valve performance parameters:
Connection method: flange, butt welding, thread
Nominal pressure/MPa: 1.0-2.5
Pressure test pressure/MPa: 1.1-2.75
Working pressure/MPa 1.0 -2.5
Shell material: gray cast iron. ductile iron. carbon steel. stainless steel
Filter material: stainless steel
Total mesh area: 3～4DN

TH Valve is a professional manufacturer of butterfly valve, gate valve, check valve, globe valve, knife gate valve, ball valve with API, JIS, DIN standard, used in Oil, Gas, Marine industry, Water supply and drainage, fire fighting, shipbuilding, water treatment and other systems, with Nominal Diameter of DN50 to DN1200, NBR/EPDM/VITON, Certificates & Approvals: DNV-GL, Lloyds, DNV, BV, API, ABS, CCS. Standards: EN 593, API609, API6D

Daily maintenance and precautions of ball valves

August 14, 2020

Daily maintenance of ball valve:
Long service life and maintenance-free period will depend on the following factors: normal working conditions, maintaining a harmonious temperature/pressure ratio, and reasonable corrosion data.

14 ball-valve-6

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

Before maintenance: relieve the pipeline pressure and leave the valve in the open position; disconnect the power or air source; separate the actuator from the bracket.

It is necessary to find out that the upstream and downstream pipelines of the ball valve have indeed been relieved of pressure before disassembling.

Care must be taken to prevent damage to the sealing surface of parts, especially non-metal parts, when disassembling and reassembling. Special tools should be used when removing O-rings.

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

The cleaning agent should be compatible with the rubber parts, plastic parts, metal parts and working medium (such as gas) in the ball valve. When the working medium is gas, gasoline (GB484-89) can be used to clean metal parts. Clean non-metal parts with pure water or alcohol.

Non-metal parts should be taken out of the cleaning agent immediately after cleaning, and should not be soaked for a long time.

After cleaning, it needs to be assembled after the cleaning agent of the wall surface to be washed evaporates (can be wiped with silk cloth not soaked in cleaning agent), but it should not be left for a long time, otherwise it will rust and be contaminated by dust.

New parts also need to be cleaned before assembly.

When assembling, it should not be allowed to have metal chips, fibers, grease (except those specified for use), dust, other impurities, foreign objects, etc., to contaminate, adhere or stay on the surface of the parts or enter the cavity. Then tighten the stem nut.

Note: Don’t lock it too tightly, usually lock 1/4 turn to 1 turn, the leakage will stop.

A), disassembly

Keep the valve in a half-open position to flush and remove dangerous substances that may exist inside and outside the valve.

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

Disassemble the drive device-actuator, connecting bracket, lock washer, stem nut, butterfly shrapnel, glam, wear-resistant piece, stem packing in order.

Remove the body cover connecting bolts and nuts, separate the valve cover from the valve body, and remove the valve cover gasket.

Make sure that the valve ball is in the “off” position. This will make it easier to take it out of the valve body, and then take out the valve seat.

Gently push the stem down from the hole in the valve body until it is completely taken out, and then take out the O-ring and the lower packing of the stem.

Note: Please operate carefully to avoid scratching the surface of the valve stem and the sealing part of the valve body stuffing box.

B), reassembly

Clean and inspect the removed parts. It is strongly recommended to replace the valve seat and valve cover gasket with spare parts kit.

Assemble in the reverse order of disassembly.

Use the specified torque to tighten the flange connecting bolts crosswise.

Tighten the stem nut with the specified torque.

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

If possible, please perform pressure seal test and performance test on the valve according to relevant standards before reinstalling the pipeline.

Applicable occasions and operation method of ball valve

August 14, 2020

Applicable occasions of ball valve:
Since the ball valve usually uses rubber, nylon and polytetrafluoroethylene as the seat sealing ring material, its use temperature is limited by the seat sealing ring material. The cut-off effect of the ball valve is accomplished by

14 ball-valve-6

pressing the metal ball against each other between the plastic valve seats under the action of the medium (floating ball valve). Under the action of certain contact pressure, the seat sealing ring has elastic-plastic deformation in some areas. This deformation can compensate the manufacturing accuracy and surface roughness of the ball, and ensure the sealing performance of the ball valve.

In addition, since the seat sealing ring of the ball valve is usually made of plastic, when selecting the structure and performance of the ball valve, the fire resistance and fire resistance of the ball valve must be considered, especially in the petroleum, chemical, metallurgical and other sectors, in the flammable and explosive media Ball valves are used in the equipment and piping systems, and more attention should be paid to fire and fire resistance.

Generally, in two-position adjustment, strict sealing performance, mud, wear, necking channel, rapid opening and closing action (1/4 turn opening and closing), high pressure cut-off (large pressure difference), low noise, cavitation and vaporization, In piping systems with a small amount of leakage to the atmosphere, small operating torque and low fluid resistance, ball valves are recommended.

Ball valves are also suitable for piping systems with light structure, low pressure cut-off (small pressure difference), and corrosive media. Ball valves can also be used in cryogenic (cryogenic) devices and pipeline systems. In the oxygen pipeline system of the metallurgical industry, ball valves that have undergone strict degreasing treatment are required. When the main line in the oil pipeline and gas pipeline needs to be buried underground, full-diameter welded ball valves are required. When the adjustment performance is required, a ball valve with a special structure with a V-shaped opening should be selected. In petroleum, petrochemical, chemical, electric power, and urban construction, metal-to-metal sealed ball valves can be used for pipeline systems with operating temperatures above 200 degrees.

Operation method of ball valve:
1) Before operation, make sure that the pipeline and valve have been flushed.

2) The operation of the valve drives the valve stem to complete rotation according to the size of the input signal of the actuator: when it rotates 1/4 turn (90°) in the forward direction, the valve is closed. When reverse rotation is 1/4 turn (90°), 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.

Basic knowledge of valve

What are the accessories for pneumatic valves?

Fasteners, fillers and gasket materials of valves

What is the material of Bolts and nuts of Valve Stem?

What is the material of the butterfly valve stem?

What is the material of the main parts of the butterfly valve?-(2)

What is the material of the main parts of the butterfly valve?-(1)

Strainer valve introduction and its features

Daily maintenance and precautions of ball valves

Applicable occasions and operation method of ball valve

TH VALVE • PROFESSIONAL VALVE MANUFACTURER

GET IN TOUCH WITH US