manufacturer Archives

Pneumatic globe valve model preparation method

July 1, 2021

Pneumatic globe valve /cut-off valve model preparation method
Pneumatic shut-off valve is used to open and close the pipeline medium by compressed air, and the action speed is relatively faster. Different materials and seals are selected, which can be applied to various pressure, temperature

and medium conditions, and the seal is reliable and the performance is excellent. However, since there are many types of pneumatic stop valves and their structural forms are changeable, users should be familiar with their model designation method when choosing pneumatic stop valves, so as to avoid problems such as selecting the wrong type, replacing goods and returning goods!
Pneumatic globe valve model preparation instructions are represented by the code of the globe valve type, drive mode, connection mode, structure form, sealing material, nominal pressure, valve body material, etc., mainly for the model description of the existing pneumatic globe valve products, such as customized When the material and structure of the globe valve products change, please select according to the valve preparation method.
Pneumatic shut-off valve model preparation method:
Additional code for stop valve: W means bellows, D means low temperature, B means heat preservation;
1) Type code of globe valve: J means globe valve;
2) Stop valve transmission mode: manual without code, 5 bevel gear, 6 pneumatic, 9 electric;
3) Connection mode of stop valve: 4 flange connection, 6 welding;
4) The structure of the globe valve: 1 straight-through type, 2 Z-type straight-through, 3 three-way, 4-angle type, 5 Y-type DC type, 6 balanced straight-through type, 7 balanced angle type, 8-pin type;
5) Seal material of globe valve: F fluorine rubber, H stainless steel, N nylon plastic, Y cemented carbide, M Monel alloy, W valve body directly processed;
6) The nominal pressure of the shut-off valve: 16 means that the pressure of 1.6mpa is 16 kilograms, PN1.6-32mpa, IN150LB-1500LB, 5-63K;
7) Globe valve body material: A titanium alloy, C carbon steel, I chromium molybdenum steel, P stainless steel 304, R stainless steel 316;
Examples for the compilation of pneumatic shut-off valve models:

pneumatic globe valve

WJ641H-16C Pneumatic Bellows Globe Valve
1. W: means bellows
2. J: represents the stop valve;
3. 6: indicates that the transmission mode is pneumatic;
4. 4: The connection method is flange connection;
5. 1: The structure is a straight flow channel;
6. H: Hard seal made of stainless steel for the sealing pair;
7. 16: Indicates that the nominal pressure is 1.6MPa;
8. C: Indicates that the valve body material is carbon steel.

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

Working Principle of Pneumatic Gate Valve

June 29, 2021

Brief introduction of pneumatic gate valve:
The pneumatic gate valve is equipped with a pneumatic actuator, which is driven by compressed air to control the gate valve. The valve core is composed of a wedge-shaped structure and a parallel structure, which is suitable for the emergency cut-off and discharge of gas and liquid pipelines.

pneumatic gate valve (3)

Working principle of pneumatic gate valve:
When using the air source to operate the gate valve, the small handle of the manual device must be turned to the pneumatic position to open and close the nut and the screw rod. When the compressed air enters from the upper pipeline of the cylinder, the piston and the piston rod in the cylinder are pushed straight When the compressed air enters from the lower pipe, the gas pushes the piston and piston rod in the cylinder to move upwards, and at the same time drives the valve stem to move upwards to open the valve. When there is no air source, the screw rod and the opening and closing nut can be used to open and close the valve. First, the upper and lower intake pipes of the cylinder are in the exhaust state, and the small handle of the manual part is in the manual position, so that the opening and closing nut and the screw are in the manual position. In the normal meshing state, turn the large handwheel at the manual part at this time. When the handwheel is turned clockwise, the valve is closed, and when the handwheel is turned counterclockwise, the valve is opened. When the air source is introduced from the upper air inlet, the valve stem drives the valve plate to move downward, and the valve is closed.
When the air source is introduced from the lower air inlet, the valve stem drives the valve plate to move upward, and the valve opens.
Pneumatic gate valve parameters:
Actuator: cylinder piston structure;
Optional accessories: manual device, filter, solenoid valve, echo device, control box;
Main material: ductile iron, cast steel, stainless steel; Caliber: DN50-500;
Pressure: PN1.6-6.4mpa;
Temperature: Q-29～350℃, C-29～450℃, P-30～540℃;
Medium range: water, steam, petroleum, gas, fluid, medium containing hard particles and impurities.

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, API6

full bore ball valve vs reduced bore ball valve

June 22, 2021

The difference and selection of full bore ball valve and reduced bore ball valve
Ball valve is currently the most widely used mechanical product in all valve markets. It is mainly composed of valve body, valve seat, ball, valve stem and transmission device. The ball core is driven to rotate through the actuator to achieve the function of switching or adjusting. . In the chemical industry, environmental protection, water treatment, urban construction, machinery, and food industries, it is widely used and very popular! there are Electric ball valve and Pneumatic ball valve, and other actuated ball valves.

Pneumatic electric high platform ball valve

There are many types of ball valves, which can be combined into various products with different functions through different structures, connection methods, pressure levels, drive forms, etc., but from the most basic point of view, ball valves have two types: full-diameter ball valves and reduced-diameter ball valves. The difference between major categories. Generally speaking, when the inner diameter of the valve ball is less than or equal to 85% of the inner diameter of the ball valve port, it is called a reduced-diameter ball valve, and when the inner diameter of the ball valve is greater than 95% of the inner diameter of the ball valve port, it is called a full-bore ball valve. So what is the difference between the two in the selection or application?
The definition of full bore ball valve and reduced bore ball valve:

fixed ball valve

1. The full-bore ball valve has equal-width flow channels, that is to say, the size of the orifices from inflow to outflow is the same, and its size cannot be less than the value specified by the standard, which is roughly equivalent to the nominal diameter of the specification, such as DN50 full-diameter The diameter of the ball valve flow path also needs to be about 50;
2. The inlet of the reduced diameter ball valve is wider than the diameter of the flow path, and the actual diameter of the flow path is about one specification smaller than this specification. For example, the diameter of the DN50 reduced diameter ball valve is about 38, which is roughly equivalent to the specification of DN40. One specification is reduced within DN250 and two specifications are reduced from 250-600. Above 600 depends on the actual situation.
Applicable medium for full bore ball valve and reduced bore ball valve:
1. The full-bore ball valve is generally used on pipelines for conveying viscous and slagging media. Because of its low fluid resistance, it can be said that there is basically no flow resistance, and it is convenient for regular wax scrapers to pass through.
2. Reduced diameter ball valve is suitable for conveying gas or pipelines with physical properties similar to water. Because its weight is about 30% lighter than a full-diameter ball valve, and its flow resistance is only 1/7 of that of a stop valve of the same diameter. about. It is helpful to reduce the pipeline load and reduce the cost.
Applicable process for full bore ball valve and reduced bore ball valve:
1. For pipelines that require regular pigging, no matter what kind of medium is transported, full-diameter ball valves must be used. The medium passing through the full-bore ball valve will not reduce the flow, and the flow resistance is small, which is an ideal product for pipeline control, especially for strict working conditions. Especially when the main line in the oil pipeline and gas pipeline needs to be buried underground, full-diameter welded ball valves must be used.
2. The reduced diameter ball valve is suitable for some working conditions such as low requirements and small convection resistance requirements. When the inner diameter of the valve is greater than 80% of the inner diameter of the pipe end, it has almost no effect on the pipeline fluid passing capacity. Many valves have a reduced diameter, which is generally controlled within 0.8. On the one hand, the reduced diameter reduces the flow capacity of the valve, that is, the Kv value of the valve, and increases the pressure drop at both ends of the valve, causing energy loss. That said, there is not much impact, and it may increase the erosion of the pipeline.
The advantages and disadvantages of full-bore ball valves and reduced-bore ball valves are compared:
1. Installation space: The reduced-diameter ball valve has a small volume, so its installation space requirements are smaller. Because its weight is about 30% lighter than a full-diameter ball valve, it is beneficial to reduce the pipeline load, reduce the transportation load and reduce the cost.
2. Cost: Reduced-diameter ball valves are one grade lower than full-diameter ball valves. Considering the cost performance, it is generally accepted internationally that adjacent pipe diameters use the same ball-diameter valve body. For example, dn32 and dn40, dn50 and dn63, dn90 and dn110, dn160 and dn200, dn250 and dn315 use the same sphere.
Note: Since the inner diameter of the reduced diameter ball valve is small, the torque on the valve stem is small, which is more suitable for prolonging the service life of the valve switch. Especially the low-torque design of large-diameter valves. However, the diameter cannot be reduced too much, otherwise the system resistance will increase. However, if the diameter is not reduced, the purchase cost will be increased, and the control characteristics of the valve will generally be reduced, which will make the adjustment effect worse. For example, if the regulating valve is always used at a small opening, the service life of the valve will be reduced.

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

Application of low temperature butterfly valve

June 22, 2021

Article title: Application of low temperature triple eccentric butterfly valve
With the rapid development of industrial technology, more stringent requirements have been put forward for valves, especially for butterfly valves used in low temperature media. In addition to meeting the performance of general valves, it is more important that butterfly valves seal under low temperature conditions. Reliability, flexibility of action and some other special requirements for cryogenic valves. Now combined with its structural characteristics, a brief introduction to the performance of the cryogenic butterfly valve is given. Remarks: The cryogenic butterfly valve we are talking about here specifically refers to the low temperature triple eccentric butterfly valve.

triple offset valve parts-after-cryogenic process

Requirements for sealing performance of low temperature triple eccentric butterfly valve:
There are two main reasons for the leakage of the low temperature triple eccentric butterfly valve, one is internal leakage; the other is external leakage.
1. Internal leakage of butterfly valve:
The main reason for the internal leakage of the valve is the deformation of the sealing pair in the low temperature state. When the temperature of the medium drops to a phase change of the material, the volume changes, which causes the sealing surface with high grinding accuracy to warp and deform, resulting in poor low-temperature sealing. We conducted a low temperature test on the DN250 valve. The medium was liquid nitrogen (-196 ℃) and the butterfly plate material was 1Cr18Ni9Ti (without low temperature treatment). It was found that the sealing surface warped and deformed up to about

cryogenic triple offset butterfly valve 1

0.12mm, which is the main cause of internal leakage. And if the plane seal of the butterfly valve is changed to a cone seal. The valve seat is an oblique cone ellipse sealing surface, which forms a sealing pair with a round elastic sealing ring embedded on the butterfly plate. The sealing ring can float radially in the butterfly plate groove. When the valve is closed, the elastic sealing ring first contacts the short axis of the elliptical sealing surface. As the valve stem rotates, the sealing ring is gradually pushed inward, forcing the elastic ring to contact the long axis of the oblique cone surface, and finally the elastic sealing ring All contact with the oval sealing surface. Its sealing is achieved by the deformation of the elastic ring. Therefore, when the valve body or butterfly plate is deformed at low temperature, it will be absorbed and compensated by the elastic sealing ring, and leakage and jamming will not occur. When the valve is opened, this elastic deformation disappears immediately, and there is basically no relative friction during the opening and closing process, so the service life is long.
2. Leakage of butterfly valve:
One is that when the valve and the pipeline are connected by flanges, leakage occurs due to the unsynchronized contraction and relaxation of the connecting gasket, connecting bolts, and connecting materials at low temperatures. Therefore, we changed the connection between the valve body and the pipeline from a flange connection to a welded structure to avoid low temperature leakage. The second is leakage at the valve stem and packing. Generally, most valve packing adopts F4 because of its good self-sliding performance, low friction coefficient (friction coefficient for steel f=0.05 ~ 0.1), and unique chemical stability, so it is widely used. However, F4 also has shortcomings. First, the tendency of cold flow is large; second, the linear expansion coefficient is large, and the cold shrinkage at low temperature causes leakage, which causes a large amount of ice at the valve stem, so that the valve fails to open. The low-temperature triple-eccentric butterfly valve developed for this purpose adopts a self-shrinking sealing structure, that is, taking advantage of the large expansion coefficient of F4, and achieves the purpose of sealing at room temperature and low temperature through the reserved gap.
Design requirements for low temperature triple eccentric butterfly valve body and stem bushing:
1. The structure and shape of the cryogenic valve shell. The correct selection of materials is of great significance to the normal and reliable operation of the valve. Compared with the stop valve and gate valve, the structural characteristics of the butterfly valve not only avoid the irregular shape and uneven shell wall thickness, which can cause problems at low temperatures. Due to the small size of the butterfly valve, the shape of the valve body is basically symmetrical, so the heat capacity is small; the pre-cooling consumption is also small; the shape is regular and it is convenient to take measures to keep the valve cold. ,
2. Selection of stem bushing: Some low-temperature triple-eccentric butterfly valves are in operation, the rotating parts of the valve are sticky, and seizure occurs from time to time. The main reason is: unreasonable selection of matching materials, too small pre-cooling clearance, and processing Causes such as low accuracy. In the development of cryogenic valves, a series of measures have been taken to prevent the occurrence of the above phenomena. For the upper and lower bushings of the valve stem, SF-1 type composite bearings with low friction coefficient and self-lubricating properties are selected, which can be suitable for some special needs of cryogenic valves. The metal-sealed butterfly valve has the characteristics that some ordinary valves do not have, especially the small flow resistance, reliable sealing, rapid opening and closing, and long service life. The triple eccentric metal sealing butterfly valve is sealed by the deformation of the elastic ring, so it does not need to rely on the force of the medium, so it can be used for two-way sealing.
Related information: The difference of cryogenic valve and ordinary temperature valve; Cryogenic valve principle |standard |illustration |selection

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

Ball valve model preparation method/code name establishment

June 11, 2021

Ball valve model preparation method/code name establishment in China.
With the rapid development of my country’s industrial modernization, the use of valves is also increasing. Ball valves have the advantages of fast opening and closing speed, and not only can switch and cut off, but also control flow, etc., and become the most widely used valve type. one! However, due to the wide variety of ball valves, including the use of pressure, temperature and control methods, the corresponding ball valve models are also different. In order to avoid errors in the selection of the user, and to ensure that the ball valve can be used normally, more instruments Self-Control Valve Company hereby provides instructions for the preparation of ball valve models for everyone to understand and recognize!

Pneumatic electric high platform ball valve

Ball valve model editing instructions are mainly from the increase of additional conditions of the ball valve, the selection of the drive mode, the difference of the connection form, the change of the structure form, the type of sealing material, the level of valve pressure and the material of the valve body, etc. to facilitate the explanation, hope It is helpful to the majority of users.
Ball valve model representation method:
Ball valve additional code: V means the valve core has a V-shaped structure, D means low temperature, B means heat preservation, P means eccentric structure, U, S and DY mostly mean top-mounted type;
Ball valve name code: Q means ball valve; Ball valve drive code: 2 means electro-hydraulic, 3 means turbine, 6 means pneumatic, 7 means hydraulic, 9 means electric, manual without code;
Code of connection method: 1 means internal thread, 4 means flange type, 6 means welding, 7 means wafer type;
Structural type code: Floating type: 1 means straight-through runner, 2 means Y-type tee, 4 means L-type tee, 5 means T-type tee; Fixed type: 0 means hemispherical through, 6 means four-way runner, 7 Means straight-through flow to, 8 means L-type tee, 9 means Y-type tee;

fixed ball valve

Sealing material code: B babbitt alloy, F fluorine rubber, F46 lining fluorine, H stainless steel, J rubber lining, M Monel alloy, N nylon plastic, Monel P, Y cemented carbide, W valve body directly processed;
Pressure rating code: 16 means the pressure is 16 kg (1.6Mpa) and the maximum can reach 64Mpa; 150LB means the American standard pound pressure, and the maximum pressure rating can reach 2500LB (150LB=1.6MPA/300LB=2.5-4.0mpa/400LB=6.4 mpa/600LB=10mpa); 5K means Japanese pressure, maximum pressure is 63K; Valve body material code: A titanium and titanium alloy, C carbon steel, I chromium molybdenum steel, P18-8 series stainless steel, RMo2Ti series stainless steel, S plastic.
ball valve model editing instructions:
Q645F-16P Stainless steel pneumatic flange three-way ball valve
1. Q: represents the ball valve;
2. 6: It means that the transmission mode is pneumatic;
3. 4: The connection method is flange connection;
4. 5: The structure is a floating T-type tee;
5. F: The sealing material is fluorine rubber;
6. 16: Indicates that the nominal pressure is 1.6MPa;
7. P: indicates that the valve body is made of stainless steel.

Editing instructions for electric ball valve model:
VQ947F-16P Stainless steel electric flange V-shaped ball valve
1. V: indicates that the spool has a V-shaped structure
2. Q: represents the ball valve;
3. 9: indicates that the transmission mode is electric;
4. 4: The connection method is flange connection;
5. 7: The structure is a fixed straight flow channel;
6. F: The sealing material is fluorine rubber;
7. 16: Indicates that the nominal pressure is 1.6MPa;
8. P: indicates that the valve body is made of stainless steel.

More details for valve model establishment, you can visit another article: https://www.tanghaivalve.com/valve-model-establishment-and-meaning/

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

7 types of flange sealing surface: FF, RF, M, FM, T, G, RTJ

April 20, 2021

Flanged butterfly valve has a flange on the valve, and bolts are used to connect the flanges at both ends of the valve to the pipe flange. Do you know all the 7 types of flange sealing surfaces? FF, RF, MF, M, T, G, RTJ
The flange sealing surface basically has:

Full plane: FF
Raised face: RF
Concave/female: FM
Convex/Male: M
Tenon: T
Groove surface: G
Ring connection surface RTJ (RJ) types, according to the different working conditions, medium, pressure, specifications, temperature, etc., so the selected types are not the same. Let’s get to know the types of these flange sealing surfaces together!
FF-full plane:
Flat Face Full Face type sealing surface is completely flat, suitable for occasions where the pressure is not high and the medium is non-toxic.

flange FF

RF-raised face:
The Raised Face type of sealing surface is the most widely used among several types, and the most commonly used one. The international standards, European system and domestic standards are all fixed heights, but in the American standard flange, it should be noted that the height of high pressure will increase the sealing surface. There are also many types of gaskets used. Gaskets suitable for raised face sealing surface flanges include various non-metallic flat gaskets, coated gaskets; metal-wrapped gaskets; spiral wound gaskets (including outer ring or inner and outer ring).

flange RF

Convex/Male: M
Concave /female: FM
The two types of sealing surfaces, Male Face and Female Face, are a pair, one female and one male. They must be used together. They are easy to align and prevent the gasket from being extruded. Suitable for occasions with higher pressure.
The suitable sealing gaskets for the concave-convex sealing surface include: various non-metallic flat gaskets and coated gaskets; metal-clad gaskets; basic type or winding stopper with inner ring, etc.
T-tenon
G-groove surface
Tongue Face and Groove Face are similar to the concave-convex surface. They are also a male and female matched sealing surface type, and they are also used in pairs. The gasket is located in the annular groove and is restricted by the metal walls on both sides. It can prevent the gasket from being compressed and deformed and squeezed into the pipeline. Since the gasket is not in direct contact with the fluid medium in the pipe, it is less eroded or corroded by the fluid medium, so it can be used for high pressure, flammable, explosive, and toxic mediums that require strict sealing. This kind of sealing surface gasket has good installation and neutrality, but it is difficult to process the sealing surface. It is easy to damage the sealing surface when replacing the gasket, and the flange must be separated in the axial direction during installation and disassembly. Therefore, consideration should be given to the pipeline design. It is possible to separate the flange in the axial direction.
Suitable gaskets for the sealing surface of the tongue and groove surface include: various metal and non-metal flat gaskets, metal-clad gaskets and basic spiral wound gaskets.

flange TG-

RTJ(RJ)-Ring connection surface
The flange of the Ring Joint Face seal is also a narrow-face flange, and an annular trapezoidal groove is opened on the flange surface as the flange sealing surface, which is the same as the tongue-and-groove flange. The flange must be separated in the axial direction during installation and disassembly. Therefore, the possibility of separating the flange in the axial direction should be considered in the pipeline design.
The sealing surface is specially designed to cooperate with solid metal gaskets processed into octagonal or elliptical shapes from metal materials to achieve a sealed connection. Since the metal ring gasket can be based on the inherent characteristics of various metals, the sealing performance of this sealing surface is good, and the installation requirements are not too strict. It is suitable for high temperature and high pressure working conditions, but the processing accuracy of the sealing surface is relatively high. (According to the Pipe Fittings, Pumps and Valves Alliance)

flange-RTJ-RJ-

flange-RTJ-RJ-02

The chemical composition, characteristics and applications of rubbers

December 30, 2020

Here we will introduce Rubber variety (abbreviated symbol) with their Chemical composition, Performance characteristics and Main application.

1. Natural rubber (NR) is mainly rubber hydrocarbon (polyisoprene), containing a small amount of protein, moisture, resin acid, sugar and inorganic salt. Large elasticity, high tensile strength, excellent tear resistance and electrical insulation, good wear resistance and drought resistance, good processability, easy to bond with other materials, and superior to most synthetic rubbers in comprehensive performance. Disadvantages are poor resistance to oxygen and ozone, easy to aging and deterioration; poor resistance to oil and solvents, low resistance to acid and alkali, and low heat resistance. Operating temperature range: about -60℃~+80℃. Production of tires, rubber shoes, hoses, tapes, insulation layers and sheaths of wires and cables, and other general products. It is especially suitable for manufacturing torsional vibration eliminators, engine shock absorbers, machine supports, rubber-metal

lug type butterfly valve-ductile iron

suspension components, diaphragms, and molded products.

2. Styrene butadiene rubber (SBR) is a copolymer of butadiene and styrene.
The performance is close to natural rubber, and it is currently the largest output of general-purpose synthetic rubber. It is characterized by abrasion resistance, aging resistance and heat resistance exceeding natural rubber, and its texture is more uniform than natural rubber. The disadvantages are: low elasticity, poor flex resistance and tear resistance; poor processing performance, especially poor self-adhesiveness and low green rubber strength. Operating temperature range: about -50℃~＋100℃.
Mainly used to replace natural rubber to make tires, rubber sheets, hoses, rubber shoes and other general products.

3. Butadiene rubber (BR)
It is a cis-structure rubber formed by polymerization of butadiene. The advantages are: excellent elasticity and wear resistance, good aging resistance, excellent low temperature resistance, low heat generation under dynamic load, and easy metal bonding. The disadvantages are low strength, poor tear resistance, poor processing performance and self-adhesiveness. Operating temperature range: about -60℃~＋100℃.
Generally used together with natural rubber or styrene-butadiene rubber, mainly to make tire treads, conveyor belts and special cold-resistant products.

4. Isoprene rubber (IR) is a kind of cis structure rubber made by polymerization of isoprene monomer. The che

Wafer butterfly valve-PN20-WCB-ANSI-150 (4)

mical composition and three-dimensional structure are similar to natural rubber, and the performance is very close to natural rubber, so it is called synthetic natural rubber. It has most of the advantages of natural rubber. Due to its aging resistance, natural rubber has slightly lower elasticity and strength than natural rubber, poor processing performance and higher cost. Operating temperature range: about -50℃~+100℃ It can replace natural rubber to make tires, rubber shoes, hoses, tapes and other general products.

5. Chloroprene rubber (CR) is a polymer formed by emulsion polymerization of chloroprene as monomer.
This kind of rubber contains chlorine atoms in its molecule, so compared with other general rubbers: it has excellent antioxidant, ozone resistance, non-flammable, self-extinguishing after fire, oil resistance, solvent resistance, acid and alkali resistance, aging and gas resistance. Advantages such as good tightness;
Its physical and mechanical properties are also better than natural rubber, so it can be used as general-purpose rubber as well as special rubber. The main disadvantages are poor cold resistance, large specific gravity, high relative cost, poor electrical insulation, and easy sticking, scorching, and mold sticking during processing. In addition, the raw rubber has poor stability and is not easy to store. Operating temperature range: about -45℃~＋100℃. It is mainly used to manufacture cable sheaths and various protective covers and protective covers that require high ozone resistance and high aging resistance; oil and chemical resistance hoses, tapes and chemical linings; flame-resistant rubber products for underground mining, and various moldings Products, sealing rings, gaskets, adhesives, etc.

6. Butyl rubber (IIR) is a copolymer of isobutylene and a small amount of isoprene or butadiene. The biggest feature is good air tightness, good ozone resistance, good aging resistance, high heat resistance, long-term working temperature can be below 130 ℃; resistance to strong inorganic acids (such as sulfuric acid, nitric acid, etc.) and general organic solvents, vibration absorption and damping characteristics Good and very good electrical insulation. The disadvantages are poor elasticity, poor processing performance, slow vulcanization speed, and poor adhesion and oil resistance. Operating temperature range: about -40℃~+120℃. Mainly used as inner tube, water tyre, balloon, wire and cable insulation layer, chemical equipment lining and shockproof products, heat-resistant conveyor belt, heat-resistant aging tape products.

7. Butadiene rubber (NBR) Copolymer of butadiene and acrylonitrile. It is characterized by its excellent resistance to gasoline and aliphatic hydrocarbon oils, second only to polysulfide rubber, acrylic ester and fluorine rubber, but better than other general rubbers. Good heat resistance, good air tightness, abrasion resistance and water resistance, and strong adhesion. The disadvantages are poor cold resistance and ozone resistance, low strength and elasticity, poor acid resistance, poor electrical insulation, and poor resistance to polar solvents. Operating temperature range: about -30℃~＋100℃. Mainly used to manufacture various oil-resistant products, such as hoses, sealing products, etc.

8. Hydrogenated butadiene rubber (HNBR) is a copolymer of butadiene and acrylonitrile. It is obtained by fully or partially hydrogenating the double bonds in the butadiene of NBR.
It is characterized by high mechanical strength and abrasion resistance, and its heat resistance is better than NBR when crosslinked with peroxide
Good, other properties are the same as nitrile rubber. The disadvantage is that the price is higher. Operating temperature range: about -30℃~+150℃. Mainly used for oil and high temperature resistant sealing products.

9. Ethylene propylene rubber (EPM\\EPDM)
The copolymer of ethylene and propylene is generally divided into two yuan ethylene propylene rubber and three yuan ethylene propylene rubber.
It is characterized by excellent ozone resistance, ultraviolet resistance, weather resistance and aging resistance, ranking first in general rubber. Electrical insulation, chemical resistance, impact elasticity, acid and alkali resistance, low specific gravity, high filling compounding is possible. Heat resistance up to 150°C, resistance to polar solvents-ketones, esters, etc., but not to aliphatic and aromatic hydrocarbons. Other physical and mechanical properties are slightly inferior to natural rubber and superior to styrene butadiene rubber. The disadvantage is that the self-adhesion and mutual adhesion are very poor, and it is not easy to bond. Operating temperature range: about -50℃~+150℃. Mainly used as chemical equipment lining, wire and cable sheathing, steam hose, heat-resistant conveyor belt, rubber products for automobiles and other industrial products.

10. Silicone rubber (Q)
It is a special rubber with silicon and oxygen atoms in the main chain, of which silicon element plays a major role. Its main feature is high temperature resistance (maximum 300℃) and low temperature resistance (minimum -100℃). It is currently the best high temperature resistant rubber. It has excellent electrical insulation and high stability to thermal oxidation and ozone. , Chemically inert. The disadvantage is that the mechanical strength is low, oil resistance, solvent resistance, acid and alkali resistance are poor, it is difficult to vulcanize, and the price is more expensive. Operating temperature: -60℃~+200℃.

Tanghai Valve is the best manufacturer of butterfly valve, check valve, knife gate valve in China. We produce the best quality products with competitive low prices.

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…)

URL: http://www.tanghaivalve.com

Name: Harry Li

Email: harry@tanghaivalve.com

Classification and introduction of pipe thread-(3)

December 7, 2020

Sealing pipe thread (R)

The basic dimensions and tolerances of inch sealing pipe threads

Cooperate way

There are two matching methods for inch seal pipe threads: cylindrical internal thread and conical external thread form a “column/cone” fit; conical internal thread and conical external threa

NPT thread picture

d form a “cone/cone” fit.

European countries mainly use “column/cone” matching threads; countries outside Europe mainly use “cone/cone” matching threads. The inspection gauges for the two types of threads are somewhat different; the current ISO inch seal pipe thread gauge standard (ISO 7- 2:2000) is designed according to the “column/cone” coordination system.

mark

The complete mark of inch seal pipe thread is composed of thread feature code, thread size code and rotation direction code.

The characteristic code of inch sealed cylindrical internal thread is: RP;

left &right hand thread

The characteristic code of the inch sealing cone internal thread is: RC;

The characteristic code of the inch sealing cone external thread is: R1 (used with the inch sealing cylindrical internal thread);

R2 (used in conjunction with inch sealing cone internal thread);

The rotation code of the left-hand thread is LH; the rotation code of the right-hand thread is omitted and not marked.

For sealing pipe threads, use RP/R1 and RC/R2 to indicate “column/cone” and “cone/cone” thread pairs respectively.

Unsealed pipe thread

The basic size and limit deviation of the imperial unsealed pipe

mark:

The complete mark of inch unsealed pipe thread is composed of thread feature code, thread size code, pitch diameter tolerance grade code and rotation direction code.

The characteristic code of inch unsealed cylindrical thread is: G

For inch non-sealed cylindrical internal threads, the codes for the tolerance grades of the median diameter are omitted and not marked; while the codes for the pitch diameter and metric grades of the inch non-sealed cylindrical external threads are A and B respectively.

When indicating the thread pair of the inch unsealed pipe thread, only the marking code of the external thread is marked.

Example:

Right-handed, non-sealed cylindrical female thread with size code 2: G2

Class A with size code 3, right-handed, unsealed cylindrical external thread: G3A

Grade B with size code 4, left-handed, unsealed cylindrical external thread: G4 B-LH

Thread pair consisting of a right-handed, non-sealed cylindrical internal thread and a grade A cylindrical external thread with a dimension code of 2: G2A

The inner thread is processed by pipe thread taps, and the outer thread has die.

Note: 2, 3, 4 above are code names, not inch sizes, don’t confuse

other

Conversion of 55° tapered pipe thread

55° tapered pipe thread means that the thread angle is 55° and the thread has a taper of 1:16. This series of thread is widely used in the world, and its code is different from country to country.

China UK France Japan iso

Code ZG R (outside) G PT R

R (external thread) Rc (internal) R R Rc

Conversion of 60° Conical Pipe Thread

The 60° tapered pipe thread refers to a pipe thread with a tooth profile angle of 60° and a thread taper of 1:16. This series of threads is used in the machine tool industry in my country, the United States and the former Soviet Union. Its code name was previously designated as K in our country, and later designated as Z, now it is changed to NPT.

Classification and introduction of pipe thread-(2)

December 7, 2020

“Cylinder/cone” and “cone/cone”. Two inch seal pipe threads use different thread ring gauges (cylindrical thread ring gauge and tapered thread ring gauge) and thread plug gauge (the position of the datum plane is different, the two datum planes are different Half-tooth apart). Pipe threads that pass the inspection in European countries may be unqualified if they are inspected by countries outside of Europe. In international trade, you must pay attention to this difference, otherwise there may be waste. Before 1994, the ISO standard for sealed pipe threads and their gauges The standard is designed according to the “cone/cone” coordination system. China’s imperial sealed pipe thread products can directly enter the international market. However, the pipe thread products of European countries are in a disadvantageous position. After 2000, ISO’s imperial seal The pipe thread standard and its gauge standard are designed according to the “column/cone” matching question system. Our country’s original inch seal pipe thread products will encounter difficulties when entering the international market. For this reason, China revised the inch seal pipe in 2000 Thread national standard. Change the original one thread standard into two thread standards to remind the designer to pay attention to the difference and correct selection of the two mating threads. Japan still insisted on adopting 1994 when it revised the inch seal pipe thread standard in 1999 The ISO standard a year ago. Therefore, the international inch seal pipe thread market after 2000 is more complicated, and domestic

NPT thread picture

manufacturers must be careful.

Inch sealing pipe thread is a general purpose sealing pipe thread. Sealing filler should be added to the thread pair during use. Its characteristics are economical and the processing accuracy requirements are moderate. Without sealing fillers, it can ensure that the sealed connection thread is dry sealed Pipe thread. There is no dry seal pipe thread in the inch pipe thread system.

Sealed pipe threads have two functions: mechanical connection and sealing; non-sealed pipe threads have only one function of mechanical connection. Therefore, the accuracy of sealed pipe threads is stricter than that of unsealed pipe threads. Some people see unsealed pipe threads The tolerance of the pitch diameter is half of the tolerance of the sealed pipe thread. It is considered that the accuracy of the unsealed pipe thread is higher than that of the sealed pipe thread. This view is incorrect. The sealed pipe thread has requirements for the accuracy of the tooth shape. Its large diameter, The tolerances of the pitch diameter and the minor diameter are the same; the flank angle and pitch error have a greater impact on the sealing performance. The non-sealed pipe thread basically has no requirements for the accuracy of the tooth form. The top diameter tolerance is greater than the pitch diameter tolerance; the bottom diameter There is no tolerance requirement. In addition, some people think that it is possible to use non-sealed cylindrical internal threads and sealed cylindrical external threads to form a fit. This view is also wrong. This is equivalent to relaxing the accuracy requirements of sealed internal threads, and the sealing of pipe threads There may be a problem.

Due to differences in the use of sealed pipe threads, processing accuracy, assembly and testing techniques, the pipe thread standard cannot guarantee that all threaded parts that meet the standard can be sealed. In the imperial sealed pipe thread standard, a unified thread item cannot be proposed. The accuracy requirements of the parameters. These individual thread parameters have a direct impact on the sealing performance. The fundamental way to solve the problem is to formulate their own internal control measures for their specific products. Each industry or company formulates its own internal control measures. The internal control indicators of these parameters are generally confidential. Companies in other industries are not universal, and manufacturers must have a clear understanding of this. Sealing pipe thread standards are not omnipotent, and sealing problems may require manufacturers to pay attention to them. Before 1987, China did not have American and British pipe thread standards. But In production, these two internationally commonly used pipe thread standards cannot be avoided. For this reason, the old mechanical drawing standards once stipulated the marking codes for American and British pipe threads. These thread codes are derived from the Chinese Pinyin alphabet, and have not considered the foreign Whether the standard codes of standard pipe threads are consistent. Since this standard only specifies the thread codes and not the thread parameters, the same thread code may have different thread parameters in different companies or industries. There is no basis for judging who is right and who is wrong when there is a scrap .From 1987 to 1991, China promulgated the British pipe thread standard. From then on, the pipe thread code and marking should comply with the pipe thread standard. The pipe thread code specified in the old mechanical drawing standard should be abolished immediately.

Classification and introduction of pipe thread-(1)

December 7, 2020

Pipe thread is a thread used for connection on the pipe wall to the valves. There are 55-degree unsealed pipe threads and 55-degree sealed pipe threads. Mainly used to connect pipes to make the internal and external threads fit tightly. There are two types which are straight pipes thread and tapered pipes thread.
Common pipe threads mainly include the following types: NPT, PT, G, etc.

NPT thread picture

1) NPT is the abbreviation of National (American) Pipe Thread, which belongs to the American standard 60-degree tapered pipe thread and is used in North America. Refer to GB/T12716-1991 for the national standard.

2) PT (BSPT) is the abbreviation of Pipe Thread. It is a 55-degree sealed tapered pipe thread. It belongs to the Wyeth thread family. It is mostly used in Europe and the Commonwealth countries. It is often used in the water and gas pipe industry. The taper is 1:16. Refer to GB/ T7306-2000. The domestic name is ZG.

3) G is a 55-degree non-sealed pipe thread, which belongs to the Wyeth thread family. Marked as G stands for cylindrical thread. Refer to GB/T7307-2001 for the national standard.

Metric and inch threads

Metric threads are expressed by pitch, while American and British threads are expressed by the number of threads per inch;

Metric thread is 60-degree equilateral profile, inch thread is isosceles 55-degree profile, and American thread is isosceles 60-degree profile;

Use metric units (such as mm) for metric threads, and use imperial units (such as inches) for American and British threads;

“Insiders” usually use “minutes” to refer to the thread size, one inch equals 8 points, 1/4 inch equals 2 points, and so on.

In addition, there are: ISO—Metric Thread Standard 60°; UN—Unified Thread Standard 60°; API—American Petroleum Pipe Thread Standard 60°; W—British Wyeth Thread Standard 55°.

The difference between various threads

NPT, PT, G　 are all pipe threads.

NPT is the abbreviation of National (American) Pipe Thread, which belongs to the American standard 60-degree tapered pipe thread and is used in North America. National standards can be found in GB/T12716-1991

PT is the abbreviation of Pipe Thread. It is a 55-degree sealed tapered pipe thread. It belongs to the Wyeth thread family and is mostly used in Europe and Commonwealth countries. Commonly used in water and gas pipe industry, the taper is 1:16. National standards can be found in GB/T7306-2000

G is a 55-degree non-thread sealed pipe thread, which belongs to the Wyeth thread family. Marked as G stands for cylindrical thread. National standards can be found in GB/T7307-2001

In addition, the 1/4, 1/2, and 1/8 marks in the thread refer to the diameter of the thread size, and the unit is inch. Insiders usually use points to refer to the thread size, one inch equals 8 points, 1/4 inch equals 2 points, and so on. G is the general name of pipe thread (Guan). The division of 55 and 60 degrees is functional, commonly known as pipe circle. That is, the thread is processed by a cylindrical surface.

ZG is commonly known as pipe cone, that is, the thread is processed by a conical surface. The general water pipe joints are like this. The national standard is marked as Rc metric thread to indicate the pitch, and the American thread is 60 degrees. Metric units are used for metric threads, and imperial units are used for American and British threads. Pipe thread is mainly used to connect pipelines. The internal and external threads are closely matched. There are two types of straight pipes and tapered pipes. The nominal diameter refers to the diameter of the connected pipe, obviously the thread diameter is larger than the nominal diameter. 1/4, 1/2, 1/8 are the nominal diameters of inch threads, and the unit is inches.

Inch pipe threads are derived from British Wyeth threads. The combination of Wyeth threaded pipe series and Wyeth thread profiles establishes the basic dimensions of British pipe threads. According to the 1/16 taper relationship, the radial diameter tolerance of Wyeth threads is converted into British sealed tubes. Tolerance of the axial number of threads (there is a certain amount of rounding and adjustment). Then refer to the tolerance value of the inch seal pipe thread to propose the tolerance of the inch unsealed pipe thread (the tolerance changes from one-way distribution to one-way distribution, relax the top Diameter tolerance, let go of the bottom diameter tolerance). The time for the three types of threads is:

In 1841, the British Wyeth thread was proposed, and in 1905, the new Wyeth thread standard (BS 84) was promulgated.

In 1905, the British Sealed Pipe Thread Standard (BS 21) was promulgated.

From 1905 to 1940, Wyeth Thread performed the responsibility of the imperial unsealed pipe. In 1940, the unsealed pipe thread series (BSP series) of Wyeth Thread was proposed; in 1956, the British unsealed pipe thread standard (BS 2779) was issued separately.

European countries and Commonwealth countries first accepted the imperial pipe thread standard. The ISO/TC5/SC5 Pipe Thread Standardization Technical Committee and its secretariat are controlled by European countries, and the imperial pipe thread standard was adopted by the ISO standard. In 1955, the ISO proposed the imperial sealed pipe thread Standard (ISO R 7); In 1961, ISO proposed the standard for imperial unsealed pipe threads (ISO R 228). In 1978, ISO promulgated two official standards for imperial pipe threads (ISO7-1 and ISO228-1). Threads have been generally accepted by countries outside North America and are widely used in international trade.

The inch pipe thread in the ISO standard has been converted to the metric system. The metric method of the inch pipe thread is very simple. Multiply the inch size of the original pipe thread by 25.4 to convert it to the millimeter size. The inch pipe thread size is being eliminated. The so-called use of real pipe thread standards is unrealistic. There is no distinction between real metric pipe threads and fake metric pipe threads.

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