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Cryogenic valve principle |standard |illustration |selection

June 3, 2021

Principle of Cryogenic valve|Standard of Cryogenic valve|Selection of Cryogenic valve
The so-called cryogenic valve is a kind of altra-low temperature valve, as the name implies, is a valve suitable for working in cryogenic conditions. In the valve industry, valves that tend to -40°C are called cryogenic valves. Cryogenic valves are generally used in cryogenic systems such as liquid helium, liquid hydrogen, liquefied natural gas, and air separation. The medium used is liquid helium, liquid hydrogen, liquefied natural gas, liquid nitrogen, liquid oxygen and other cryogenic fluids. Under low temperature conditions, conventional metal hard seals and non-metal soft seals cannot meet the sealing requirements. In order to ensure that cryogenic valves can operate safely and reliably at low temperatures, there are some special considerations and requirements in the design and manufacture of cryogenic valves. see photo attached is a cryogenic triple offset butterfly valve.

triple offset valve parts-after-cryogenic process

Principle of ultra-low temperature valve: For valves used in ultra-low temperature conditions, the medium temperature is very low, and the metal materials will experience low temperature cold brittleness. The strength and hardness will be greatly improved, and the plasticity and toughness will be greatly reduced. This will directly affect the performance and safety of the valve. If an ordinary valve is used, the low temperature will freeze the packing in the valve stuffing box, and it will not be able to play a sealing role. In this way, the valve needs to be lengthened from the sealing seat on the bonnet to the bottom of the stuffing box. With sufficient isolation space and heat dissipation distance, the low-temperature medium in the valve body will not freeze the packing. As shown in the figure, the part marked with 175mm is the lengthened part.

In ultra-low temperature conditions, the valve stem and valve body can only adopt stuffing box or bellows structure. There are many restrictions on the use of bellows. Generally, the structure of the stuffing box seal is adopted. The stuffing box seal structure is simple to process and convenient to maintain. However, the sealing effect cannot be guaranteed under the condition of <-40℃, so the ultra-low temperature valves are all Keep the stuffing box as far away from the material as possible, and choose packing with low temperature characteristics.

Selection of ultra-low temperature valve:

cryogenic triple offset butterfly valve 1

Valve body: Ferritic stainless steel can be used when the temperature is higher than -100°C, austenitic stainless steel can be used when the temperature is lower than -100°C, copper alloy or aluminum alloy can be used for low-pressure and small-diameter valves. Stem: Made of austenitic stainless acid-resistant steel, it needs to be properly heat-treated to increase the tensile strength. At the same time, it must be hard chrome plated (coating thickness 0.04~0.06mm) or nitriding treatment to increase the surface hardness.

Gasket: When the working temperature is higher than -196℃ and the maximum low temperature working pressure is 3MPa, the asbestos rubber sheet made from long fiber can be used; when the working temperature is higher than -196℃ and the maximum low temperature working pressure is 5MPa, it can be used. Stainless steel spiral wound gasket with asbestos, stainless steel spiral wound gasket with PTFE, or stainless steel spiral wound gasket with expanded graphite.

Fasteners: when the temperature is higher than -100°C, the bolt material is Ni, Cr-Mo and other alloy steels, which need to be properly heat-treated to prevent thread bite; when the temperature is lower than -100°C, the bolt material can be austenitic Body stainless steel. The nut material is generally Mo steel or Ni steel, and the thread surface is coated with key disulfide.

Ultra-low temperature valve design standards:

1. Design: API6D, JB/T7749

2. Valve routine inspection and test: according to API598 standard.

3. Low temperature inspection and test of valve: According to JB/T7749.

4. Drive mode: manual, bevel gear drive and electric drive device.

5. Valve seat form: The valve seat adopts a welded structure, and the sealing surface is welded with cobalt-based hard alloy to ensure the sealing performance of the valve.

6. The ram adopts an elastic structure, and a pressure relief hole is designed at the pressure inlet end.

7. One-way sealing valve body is marked with flow direction mark.

8. The low-temperature ball valve, gate valve, and stop valve adopt a long neck structure to protect the packing.

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

The difference between API, DIN valve and GB valve

June 2, 2021

The difference between American standard valve, German standard valve and national standard valve
(American Standard, German Standard, National Standard) The difference between valves:
First of all, it can be distinguished from the standard codes of various countries: GB is the national standard of China, the American standard (ANSI), and the German standard (DIN). Secondly, it can be distinguished from the model. The valve model of the national standard is named according to the pinyin letter of the valve category. For example, the safety valve is A Butterfly valve D Diaphragm valve G Check valve H Stop valve J Throttle valve L Sewage valve P Ball valve Q Trap valve S Gate valve Z and so on. ,

Globe valve (9)

There are no special specifications between American standard valves, German standard valves, and national standard valves. It is nothing more than the difference between production standards and pressure levels. The material of the valve body and internal parts are easy to say, it is nothing but cast iron, cast steel, stainless steel, etc. Taking the American standard as an example, the pressure level of the American standard ranges from 125LB to 2500LB (or 200PSI to 6000PSI), and the main standard is API, ANSI, commonly referred to as API, and ANSI valves are American standard valves; German standard valve pressures are usually PN10 to PN320. DIN standard; if it is a flanged valve, the corresponding flange standard must be adopted. The world’s major valve standards are also the American Standard Petroleum Institute API standard, the American national standard ANSI, the German standard DIN, the Japanese standard JIS, the national standard GB, the European standard EN, and the British standard BS. ,

float_ball_check_valve

Simply put, American standard valves are valves designed, manufactured, produced, and tested according to American standards. German standard valves are valves designed, manufactured, produced and tested according to German standards. The national standard valve is a valve designed, manufactured, produced and tested according to our country’s standards. The differences between the three are roughly as follows: 1. The flange standards are different; 2. The structural length is different; 3. The inspection requirements are different.
(American Standard, German Standard, National Standard) Valve Standard:
China National Standard (GB)
Chinese Ministry of Machinery Standards (JB)
American National Standard (ANSI)
American Petroleum Institute Standards (API)
American Society for Testing and Materials Standards (ASTM)
American Valve and Fitting Manufacturer Standardization Society Standard (MSS)
Japanese Industrial Standard (JIS)

German National Standard (DIN)
French National Standard (NF)
British National Standard, European Standard (BS, EN)
Other national valve standards (ГOCT, IEEE, UL)

The difference between internally and externally threaded valves

June 1, 2021

Threaded valve (also called internal threaded valve) generally refers to a valve with internal or external thread on the valve body. It is mainly divided into internal threaded valve and external threaded valve. Corresponding to the pipeline. Usually threaded valves can only be manufactured with small diameters and are used for normal pressure or low pressure projects. If they are not available for high pressure work, they need to be used with welded link valves or flanged valves.

internally threaded valve and externally threaded valve

Common threaded valves are: threaded gate valve, threaded ball valve, threaded globe valve, threaded check valve.
The difference between internal threaded valve and external threaded valve:
From the point of use: Due to price and working flow requirements, most of the valves on the market use internal threaded valves. From the channel: Taking into account the thread connection, the passage of the external thread of the same caliber is smaller than the internal thread, the flow rate is faster, and the flow rate is small.
From the appearance: Most of the internal threads are pipe threads, the external threads are mostly taper threads, and the bite-type external threads are pipe threads.
In terms of pressure resistance: The wall of the valve with external thread of the same material is usually thicker than that of the internal thread (the smaller the passage, the thicker the wall), and the pressure resistance is greater. This is the reason why valves with high pressure ratings are all external threads. To
Sealing form of threaded valve:
1. Direct sealing: internal and external threads directly play a sealing role. In order to ensure that the joints are not leaking, they are often filled with lead oil, thread hemp and PTFE raw material tape; among them, PTFE raw material tape is widely used every day; this material has good corrosion resistance and extremely sealing effect. Good, it is convenient to use and store. When disassembling, it can be completely removed, because it is a non-sticky film, which is much better than lead oil and hemp.
2. Indirect sealing: the tightening force of the thread is transmitted to the gasket between the two planes, so that the gasket plays a sealing role.
Thread standard of threaded valve:
1. International standards ISO228/1, DIN259, are internal and external parallel threads, code G or PF (BSP.F);
2. German standard ISO7/1, DIN2999, BS21, taper external thread, parallel internal thread;
3. British standard ISO7/1, BS21, internal and external tapered thread, code PT or BSP.Tr or Rc;
4. American standard ANSIB21, internal and external tapered thread, code name NPT.

Properties of Fixed ball valve

May 31, 2021

The fixed ball valve is a new generation of high-performance ball valve, suitable for long-distance pipelines and general industrial pipelines. Its strength, safety, and harsh environment resistance have been specially considered in the design, and it is suitable for various corrosive and non-corrosive media. . Compared with the floating ball valve, when working, the force generated by the fluid pressure in front of the valve on the ball is all transmitted to the bearing, and the ball will not move to the valve seat, so the valve seat will not bear excessive pressure, so the fixed ball valve The torque is small, the deformation of the valve seat is small, the sealing performance is stable, and the service life is long. It is suitable for high pressure and large diameter occasions. The fixed ball valve has two-piece and three-piece valve body structures. The middle flange is connected by bolts, and the seal adopts reinforced PTFE embedded in the stainless steel ring. The rear of the steel ring is equipped with a spring to ensure that the valve seat is tightly attached to the ball. Keep it sealed.

fixed ball valve

The fixed ball valve is a new generation of high-performance ball valve, suitable for long-distance pipelines and general industrial pipelines. Its strength, safety, and harsh environment resistance have been specially considered in the design, and it is suitable for various corrosive and non-corrosive media. . Compared with the floating ball valve, when working, the force generated by the fluid pressure in front of the valve on the ball is all transmitted to the bearing, and the ball will not move to the valve seat, so the valve seat will not bear excessive pressure, so the fixed ball valve The torque is small, the deformation of the valve seat is small, the sealing performance is stable, and the service life is long. It is suitable for high pressure and large diameter occasions. The advanced spring pre-valve seat assembly has self-tightening characteristics to achieve upstream sealing. Each valve has two valve seats, which can be sealed in each direction, so the installation has no flow direction restriction and is two-way. This valve is generally installed horizontally.

The fixed ball valve has two-piece and three-piece valve body structures. The middle flange is connected by bolts, and the seal adopts reinforced PTFE embedded in the stainless steel ring. The rear of the steel ring is equipped with a spring to ensure that the valve seat is tightly attached to the ball. Keep it sealed. Both the upper and lower valve stems are equipped with PTFE bearings to reduce friction and save labor. The bottom of the small shaft is equipped with an adjustment plate to ensure the joint position of the ball and the sealing ring. Full bore diameter: The flow aperture of the valve is the same as the inner diameter of the pipeline to facilitate the pipeline cleaning.

Product features of fixed ball valve:

Operational reliability

The relative linkage (seat and stem bearing) of the large-diameter ball valve adopts Teflon with a small friction coefficient, so the operating torque is small. In addition, the long-term lubrication of the sealing grease makes the operation more flexible.

Valve seat structure

There are two types of valve seat structures: single-seal and double-seal structures. Generally, the one with self-relief function is single-seal, and double-seal is the additional safety relief on the valve body.

Lengthened stem

The extension of the valve stem is suitable for buried and low-temperature use. The length of the extension is determined according to the needs. The operation modes include manual, pneumatic, electric, gas-liquid linkage, etc.

Security of external forces

The wall thickness of the valve body is designed in accordance with the safety regulations of the high-pressure vessel, and meets the requirements of API6D for withstanding external force and bending resistance, and has sufficient strength.

As shown in the figure, the sealing of the gland part adopts four O-rings and a sealing grease injection device.

Performance advantages of fixed ball valves

Labor-saving operation: The ball is supported by the upper and lower bearings to reduce friction and eliminate the excessive torque caused by the huge sealing load formed by the imported pressure pushing the ball and the sealing seat.
Reliable sealing performance: PTFE material sealing ring is embedded in the stainless steel valve seat, and the end of the metal valve seat is equipped with a spring to ensure sufficient pre-tightening force of the sealing ring. When the sealing surface of the valve wears during use, it will be under the action of the spring. The valve continues to ensure good sealing performance.
Fireproof structure: In order to prevent the PTFE seal ring from being burnt due to sudden heat or fire, and large leakage occurs, which encourages the fire, a fireproof seal ring is set between the ball and the valve seat. When the seal ring is burned, Under the action of the spring force, the valve seat sealing ring is quickly pushed to the ball to form a metal-to-metal seal, which has a certain degree of sealing effect. The fire resistance test meets the requirements of AP16FA and API607 standards.
Automatic pressure relief function: When the pressure of the stagnant medium in the valve cavity rises abnormally and exceeds the pre-load of the spring, the valve seat retreats from the sphere to achieve the effect of automatic pressure relief. The valve seat automatically recovers after pressure relief.
Drainage pipeline: Drain holes are set up and down the valve body to check whether the valve seat is leaking. During work, when the valve is fully open or fully closed, the pressure in the middle cavity can be removed, and the packing can be directly replaced; the middle cavity can be discharged. Retentate, reduce the pollution of the medium to the valve.

Main features of fixed ball valve:

advantages of fixed ball valve:

Double blocking and discharge function: the fixed ball valve adopts spring pre-tensioned floating seat, no matter the valve is in the fully open or fully closed state, the upstream and downstream valve seats block the fluid, and the retentate in the valve body is discharged through the discharge valve. .
Automatic pressure relief function: When the temperature of the medium in the valve body cavity increases and causes abnormal pressure rise, it does not need to pass through the safety valve, but the valve seat function can automatically relieve the pressure, which is to ensure the safety of the valve when transporting liquid media. Sex is very important.
Fire safety structure: All valves have fire safety functions, and their design and manufacturing follow the requirements of API 607 and API 6FA.

Disadvantage of fixed ball valve:

Sealing emergency grease injection rescue: due to foreign matter in the medium or fire causing the valve seat seal to fail unexpectedly, the grease injection valve provides a quick connection with the grease injection gun, and the imported pump can easily and quickly inject the sealing grease into the valve seat sealing part. Mitigating leakage.
Reliable valve stem sealing and low operating torque: In addition to the standard sealing ring, an O-ring seal is also set on the packing gland. The double seal ensures the reliability of the valve stem seal; additional graphite packing and sealing grease Injection minimizes valve stem leakage after a fire. The valve stem sliding bearing and thrust bearing make the valve easy to operate.
Full diameter or reduced diameter: Full diameter or reduced diameter structure can be selected according to needs. The flow aperture of the full-bore valve is the same as the inner diameter of the pipeline, which is convenient for pipeline cleaning.
The valve stem can be lengthened: According to the needs of installation or operation, the valve stem can be lengthened. The extended stem ball valve is especially suitable for occasions where pipelines need to be buried in the ground, such as city gas. The size of the lengthened stem is determined according to customer needs.
Flexible operation: The valve seat and stem bearing with small friction coefficient and good self-lubricating property are adopted, which greatly reduces the operating torque of the valve. Therefore, even in the absence of sealing grease, the valve can be operated flexibly for a long time.

Application range of fixed ball valve:

The fixed ball valve is suitable for various pipelines of Class150～Class1500, PN16～PN100, JIS 10K～JIS 20K, applicable temperature: -196～350℃, used to cut off or connect the medium in the pipeline. Different materials can be selected. They are suitable for transporting water, steam, oil, nitric acid, acetic acid, oxidizing media, urea, etc., and are widely used in petroleum refining, long-distance pipelines, chemical industry, papermaking, pharmaceuticals, water conservancy, electric power, municipal administration, steel and other fields. The driving mode of the fixed ball valve is worm gear drive, manual, pneumatic or electric. The fixed ball valve generally adopts flange connection, but also can adopt butt welding connection.

Related types of valves:

We can also produce gate valve, check valve, globe valve, knife gate 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,

The difference between fixed ball valve and floating ball valve

May 28, 2021

There are many types of ball valves, such as hard-sealed ball valves, soft-sealed ball valves, welded half-ball valves, V-shaped ball valves, flanged ball valves, wafer ball valves, fixed ball valves, and floating ball valves. These classifications are based on the actual use of the manufacturer and the actual situation of the customer. Need, it is slowly researched and developed, but no matter how it develops, it is inseparable from the design principle of the ball valve. The so-called new product of the ball valve, no matter what kind of ball valve is developed, the principle and design plan are designed around the main body of the ball valve. The principles and standards come.
Here, we mainly talk about fixed ball valves and floating ball valves.

14 ball-valve-6

The more intuitive difference between the fixed ball valve and the floating ball valve is that the fixed ball valve is located at the lower end of the valve, and there is a stem supporting hole corresponding to the upper stem. The upper and lower stems firmly fix the spool of the ball valve to make the spool of this valve. Can not roll at will. The sealing principle is that the valve seats on both sides are pressed against the fixed ball core in the middle, so that the valve has a sealing function.
The soft sealing ball valve is round at the lower end of the valve without opening. The ball core is only fixed unilaterally by the upper stem. The ball core can move freely inside the valve cavity. When sealing, the valve seats on both sides of the ball valve are fixed. The valve seat is pressed by the valve core to produce a sealing effect.
Generally speaking, fixed ball valves are suitable for large diameters and high pressure ball valves when the pressure is relatively high. The soft-sealed ball valve is suitable for small caliber, and is suitable for low-pressure sealing ball valve when the pressure is relatively low.
The main feature of the floating ball valve is that the ball has no supporting shaft. The ball is supported by the valve seats at the inlet and outlet ends of the valve. The valve stem and the ball are movably connected. The ball of this ball valve is held in a “floating state” by two valve seats.

The ball can freely rotate between the two valve seats through the valve stem by means of a handle or other driving device.

When the flow channel hole of the ball is aligned with the valve channel hole, the ball valve is in an open state, the fluid is unblocked, and the fluid resistance of the valve is small. When the ball is rotated by 90°C, the flow channel hole of the ball is perpendicular to the valve channel hole, and the ball valve is in a closed state. Under the action of fluid pressure, the ball is pushed to the valve seat at the outlet end of the valve (referred to as the back of the valve) to make it press Tighten and ensure sealing.

Features of floating ball valve:
Under the action of the pressure difference, the ball will move slightly downstream of the valve;
The sealing performance of the ball valve mainly depends on its downstream valve seat;
The valve seat cannot move between the ball and the valve body.

Features of fixed ball valve:

The ball of the fixed ball valve is connected with the upper and lower stems as a whole, or made into an integral connecting ball, that is, the ball is forged (welded) with the upper and lower stems and mounted on the bearing. The ball can be aligned with the valve channel. The vertical axis rotates freely, but cannot move along the channel axis.

Therefore, when the fixed ball valve is working, all the force generated by the fluid pressure in front of the valve on the ball is transmitted to the bearing, and the ball will not move to the rear valve seat, so the valve seat will not bear excessive pressure, so the fixed ball valve The torque is small, the deformation of the valve seat is small, the sealing performance is stable, and the service life is long. It is suitable for high pressure and large diameter occasions.
Function of fixed ball valve
The function of preventing the valve stem from blowing out
Double cut and bleed (DBB) function
Safety function (fire protection function)
The function of injecting sealing grease when the valve leaks
Piston effect of ball valve seat (two-way piston effect of G series ball valve)
The purpose of the two-way piston effect: automatically release the pressure in the cavity of the valve body.
The use of the one-way piston effect: After the upstream valve seat is damaged, the fluid flows into the middle cavity, and the pressure in the middle cavity is higher than the pressure downstream of the valve.
Floating ball valve design should focus on the medium load to be considered in the material of the sealing ring. Excessive medium pressure will affect the life of the valve seat, and the ball can only have a slight offset. Therefore, the floating ball valve is generally suitable for DN200 or below DN200. The ball of the fixed ball valve whose nominal pressure does not exceed CLASS600Lb (10.0MPa) is fixed in the middle of the valve body by the upper and lower stems, and will not move after being pressed. The sealing of the fixed ball valve is to ensure the sealing by providing sufficient pre-tightening force through the leaf spring or cylindrical compression spring on the sealing valve seat, which is a double-sided forced sealing. The ball is supported by the upper and lower bearings, reducing friction, eliminating the excessive torque caused by the huge sealing load formed by the imported pressure pushing the ball and the sealing seat, and the operation is labor-saving. The fixed ball valve is double-sided and sealed on both sides, which will form a sealed cavity between the two sealed valve seats. To avoid danger, the fixed ball valve must be designed with an automatic pressure relief function, that is, when the pressure of the stagnant medium in the valve cavity increases abnormally and exceeds the spring At the time of pre-force, the valve seat retreats away from the sphere to achieve the effect of automatic pressure relief. After pressure relief, the valve seat automatically recovers. The fixed ball valve is widely applicable to various process pipelines with large diameter and high pressure due to its structural characteristics. Due to the need to assemble the upper and lower stems, only ball valves with a nominal diameter of DN50 or above can be produced. The nominal diameter is too small to be assembled.

Structure of fixed ball valve
1). Sphere
After introducing the various structural forms of the seal seat, I came to observe the ball structure of the same ball valve. The most important feature of the Tongding ball valve is that the ball does not deviate from the center of the sphere during the process of storing and opening. The ball I: the design of the pivot has three structural forms:
① the upper part of the sphere has a shaft, and the lower part is a shaft hole for a fixed shaft to insert. The structure of the sphere is a shaft and a hole structure.
② there are two upper and lower shaft holes on the sphere, which are inserted by the upper shaft and the lower shaft respectively. The structure is suitable for small diameters. The insertion depth of the hole is short, and it can only bear a small medium force. The structure is suitable for large diameters, can bear a large medium force, and the supporting journal is separated from the drive shaft. The drive shaft only bears the effect of torque.
③ there are two extending shafts on the sphere, two supporting plates vertically up and down. The medium force is transmitted to the valve body through the journal and the supporting plate. Similarly, the drive shaft only bears a single rotation. The moment action separates the medium force and the operating moment.

2). the valve body

Since the valve body is a forged cylinder, there is no usual valve neck. The valve neck is replaced by a stuffing box. The stuffing box is fixed on the platform of the valve body by bolts. The shaft seal is made of O-shaped rubber ring. The connecting support plate of the valve is also fixed on the valve body through the through hole on the stuffing box. It can be seen that the strength of the valve body in the journal part of this cylindrical structure is greatly weakened.

As for the structure of the valve body, like the floating ball valve, there are two types: side-mounted and top-mounted.

The side-mounted type can be divided into two sections, a main valve body and a secondary valve body structure, or a three-section type, a main valve body and two secondary valve body structures.

The top-mounted valve body is an integral structure. The upper valve cover uses bolts to form a complete pressure boundary with the valve body. The ball is a ball with upper and lower support shafts. The lower support bearing is embedded in the valve body, and the upper support bearing is placed in the valve cover. , The upper shaft end is machined with a groove connected to the flange of the shaft head to transmit torque. The medium force acts on the bearing. The drive shaft only transmits torque. It is designed as a blow-out prevention structure. The design of the valve seat The difficulty of assembly or disassembly is that the valve seat must move to both sides when the ball is installed in the valve cavity. In this way, a slidable back valve seat is designed. The valve seat is retracted into the left and right channels in advance. After the ball is installed, pass the back The flange on the valve pushes the valve seat to the center of the ball, and then uses a snap ring to snap into the groove of the back valve seat. When disassembling, first take out the snap ring, and then push the valve seat into the left and right sides of the valve cavity. In the right channel, the sphere can be taken out from the upper part. Therefore, the top-mounted structural ball has the advantage of being able to be repaired online.

Related types of valves:

All types of check valve and its structures

May 26, 2021

Check valve refers to a valve whose opening and closing parts are circular discs and rely on its own weight and medium pressure to generate actions to block the back flow of the medium. It is an automatic valve, also known as one-way valve, non-return valve(NSV) or isolation valve. The movement of the disc is divided into lift type and swing type. The lift check valve is similar in structure to the shut-off valve, but lacks the valve stem that drives the disc. The medium flows in from the inlet end (lower side) and flows out from the outlet end (upper side). When the inlet pressure is greater than the sum of the weight of the disc and its flow resistance, the valve is opened. On the contrary, the valve is closed when the medium flows back. The swing check valve has a disc that is inclined and can rotate around the axis, and the working principle is similar to that of the lift check valve. The check valve is often used as the bottom valve of the pumping device to prevent the backflow of water. The combination of check valve and stop valve can play a role of safety isolation. The disadvantage is that the resistance is large and the sealing performance is poor when closed.

all types of check valve and structures -code names-photos

The working principle of the check valve:
Check valves can also be used to supply pipelines for auxiliary systems where the pressure may rise above the system pressure. Check valves can be divided into swing check valves (rotating according to the center of gravity) and lift check valves (moving along the axis).

The function of this type of check valve is to only allow the medium to flow in one direction and prevent the flow in the opposite direction. Usually this kind of valve works automatically. Under the action of the fluid pressure flowing in one direction, the valve flap opens; when the fluid flows in the opposite direction, the fluid pressure and the self-coincidence of the valve flap act on the valve seat, thereby cutting off the flow.

Among them, the check valve belongs to this type of valve, which includes swing check valve and lift check valve. The swing check valve has a hinge mechanism and a valve disc like a door that rests freely on the inclined valve seat surface. In order to ensure that the valve clack can reach the proper position of the valve seat surface every time, the valve clack is designed in a hinge mechanism so that the valve clack has enough space for rotation and makes the valve clack truly and comprehensively contact the valve seat. The valve clack can be made of metal, leather, rubber, or synthetic covering can be inlaid on the metal, depending on the performance requirements. When the swing check valve is fully opened, the fluid pressure is almost unimpeded, so the pressure drop through the valve is relatively small. The valve disc of the lift check valve is located on the sealing surface of the valve seat on the valve body. Except that the disc can be raised and lowered freely, the rest of the valve is like a shut-off valve. The fluid pressure lifts the disc from the seat sealing surface, and the backflow of the medium causes the disc to fall back onto the seat and cut off the flow. According to the conditions of use, the valve clack can be an all-metal structure, or it can be in the form of a rubber pad or a rubber ring inlaid on the valve clack frame. Like a shut-off valve, the passage of fluid through the lift check valve is also narrow, so the pressure drop through the lift check valve is larger than that of the swing check valve, and the flow rate of the swing check valve is restricted. Rarely.
Classification of check valves:
The valve that opens or closes on its own by the force of the flow of the medium to prevent the medium from flowing back is called a check valve. Check valves belong to the category of automatic valves, which are mainly used in pipelines where the medium flows in one direction, and only allow the medium to flow in one direction to prevent accidents.

Classified by structure:
According to the structure, it can be divided into three types: lift check valve, swing check valve and butterfly check valve:

1. Lift check valves are divided into two types: vertical and horizontal.

2. The swing check valve is divided into three types: single, double and multiple.

3. The butterfly check valve is a straight-through type.

The above check valves can be divided into four types in connection form: threaded connection, flange connection, welding connection and wafer connection.

The selection criteria of the check valve are as follows:

1. In order to prevent the medium from flowing back, check valves should be installed on the equipment, devices and pipelines;

2. Check valves are generally suitable for clean media, not for media containing solid particles and high viscosity;

3. Generally, horizontal lift check valves should be used on horizontal pipes with a nominal diameter of 50mm;

4. The straight-through lift check valve can only be installed in horizontal pipelines;

5. For the inlet pipeline of the water pump, a bottom valve should be used. The bottom valve is generally only installed on the vertical pipeline at the inlet of the pump, and the medium flows from bottom to top;

6. Compared with the swing type, the lifting type has better sealing performance and greater fluid resistance. The horizontal type should be installed on the horizontal pipeline, and the vertical type on the vertical pipeline;

7. The installation position of the swing check valve is not restricted. It can be installed on a horizontal, vertical or inclined pipeline. If installed on a vertical pipeline, the flow direction of the medium should be from bottom to top;

8. The swing check valve should not be made into a small-diameter valve, it can be made into a high working pressure, the nominal pressure can reach 42MPa, and the nominal diameter can also be large, the maximum can reach more than 2000mm. According to the different materials of the shell and the sealing parts, it can be applied to any working medium and any working temperature range. The medium is water, steam, gas, corrosive medium, oil, medicine, etc. The working temperature range of the medium is between -196–800℃;

9. The applicable occasion for swing check valve is low pressure and large diameter, and the installation occasion is restricted;

10. The installation position of the butterfly check valve is not restricted. It can be installed on a horizontal pipeline, or on a vertical or inclined pipeline;

11. Diaphragm check valve is suitable for pipelines that are prone to water hammer. The diaphragm can eliminate the water hammer caused by the reverse flow of the medium. It is generally used on low-pressure and normal temperature pipelines, and is especially suitable for tap water pipelines. Normal media work The temperature is between -12-120℃, and the working pressure is less than 1.6MPa, but the diaphragm check valve can achieve a larger diameter, and the maximum DN can reach more than 2000mm;

12. The spherical check valve is suitable for medium and low pressure pipelines and can be made into a large diameter;

13. The shell material of the spherical check valve can be made of stainless steel, and the hollow sphere of the seal can be wrapped with polytetrafluoroethylene engineering plastic, so it can also be applied to the pipeline of general corrosive media, and the working temperature is -101–150 Between ℃, its nominal pressure is ≤4.0MPa, and the nominal passage range is between DN200-DN1200;

14. When selecting check valves for incompressible fluids, the required closing speed must be evaluated first, and the second step is to select the type of check valve that may meet the required closing speed;

15. The check valve for compressible fluid can be selected according to the similar method of check valve for incompressible fluid. If the medium flow range is large, the check valve for compressible fluid can be used A deceleration device, if the medium flow is stopped and started quickly and continuously, such as the outlet of the compressor, a lift check valve is used;

16. The corresponding size of the check valve should be determined, and the valve supplier must provide the data of the selected size, so that the valve size when the valve is fully opened at a given flow rate can be found;

17. For high and medium pressure check valves below DN50mm, vertical lift check valves and straight-through lift check valves should be used;

18. For low-pressure check valves below DN50mm, butterfly check valves, vertical lift check valves and diaphragm check valves should be used;

19. For high and medium pressure check valves with DN greater than 50mm and less than 600mm, swing check valves should be used;

20. For medium and low pressure check valves with DN greater than 200mm and less than 1200mm, wear-free spherical check valves should be used;

21. For low pressure check valves with DN greater than 50mm and less than 2000mm, butterfly check valves and diaphragm check valves should be used;

22. For pipelines that require relatively small water hammer impact or no water hammer when closed, slow-closing swing check valves and slow-closing butterfly check valves should be selected.

Types of check valves we produce:

We have other types of check valves: single-disc swing check valve, dual plate check valve, tilting disc swing check valve, lift swing check valve, silent check valve and ball check vlave 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,

The difference between fluoroplastics PTFE and PFA

February 5, 2021

With the gradual popularity of PFA in the market, more and more customers are beginning to contact and understand this new material. Although I have a preliminary understanding, I am not very familiar with it. Customers still have many questions about this material. Recently, customers often ask about the difference between “soluble polytetrafluoroethylene (PFA)” and “polytetrafluoroethylene (PTFE)” for this new material. Today, we will briefly explain here:

Fluorine lined butterfly valve-PTFE-WAFER (4)

The first is the difference in chemical structure:

PFA has added perfluoroalkoxy, which is equivalent to replacing one fluorine atom in PTFE with perfluoroalkoxy. A carbon is directly connected to an oxygen, and then the oxygen is connected to a group such as perfluoromethyl or perfluoroethyl. Compared with PTFE, the melt viscosity is reduced to facilitate processing. The other properties are not much worse than PTFE.

The second is the difference between applications:

PFA-has the same excellent properties as polytetrafluoroethylene, and has good thermoplasticity. It can be processed by ordinary thermoplastic resin processing methods. It is made by copolymerization of tetrafluoroethylene and perfluoropropyl vinyl ether in a certain proportion in an aqueous medium containing perfluorocarboxylate dispersant and persulfate initiator. It is a white translucent particle. It not only has the same operating temperature as PTFE, but also has better mechanical strength (about 2 to 3 times) at 250°C, and has excellent stress crack resistance. It has a wide processing range and good molding performance, and is suitable for molding processing such as compression molding, extrusion molding, injection molding, and transfer molding. It can be used to make wire and cable insulation sheaths, high frequency and ultra high frequency insulation parts, chemical pipelines, valves and pumps corrosion-resistant lining; special parts for machinery industry, various anti-corrosion materials for light and textile industry, PTFE anti-corrosion

Fluorine lined butterfly valve-PTFE-WAFER (8)

lining Wait for the electrode. It is made by extruding meltable polytetrafluoroethylene pellets, with translucent milky white appearance, smooth surface, and dense and uniform cross-section. It is specially used for welding PTFE plates and tubes, so that PTFE products with simple shapes can be welded into products with complex shapes and larger sizes. The aqueous dispersion is a copolymer obtained by copolymerizing tetrafluoroethylene and perfluoropropyl vinyl ether, adding an emulsifier, and concentrating at a certain temperature. The solid content is 30%±1%. The appearance is milky white or light yellow translucent. It has various excellent properties of fusible polytetrafluoroethylene resin. It can be used for a long time at 260℃, and developed into advanced coatings with its excellent anti-sticking, anti-corrosion and easy processing properties. It can be sprayed and dipped, and is widely used in copy technology and food industry as anti-stick and anti-corrosion materials.

PTFE-Polytetrafluoroethylene is made by polymerizing tetrafluoroethylene monomer by suspension method or dispersion method. Molecular weight=5.2×105-4.5×107. White powder, 400 mesh accounted for 75%, tasteless, non-beauty and non-toxic. The relative density is 2.1-2.3, the refractive index is 1.37, the glass transition temperature is 327℃, and the thermal decomposition temperature is 415℃. Above 400°C, there is a slight weight loss and decomposes toxic gases. Use temperature -250～260 ℃, use at 210 ℃ up to 10000h. Excellent chemical resistance, resistance to any strong acid (including aqua regia), strong alkali, grease, insoluble in any solvent, very low friction coefficient, good wear resistance, and self-lubricating. Excellent aging resistance. Excellent electrical performance, good arc resistance. It is non-sticky, almost all sticky substances cannot adhere to its surface, and it is completely non-flammable. Known as the “Plastic King”. Tensile strength (MPa)>23 and elongation (%)>250.

Again, the difference in processing methods:

The main difference in processing methods is that PFA can be processed by hot melt injection molding, while PTFE cannot be processed by hot melt injection molding.

The above is the introduction to the difference between PFA and PTFE materials. For a long time in the past, PTFE has been sought after by the industry because of its superior physical and chemical properties. However, the limitations of its processing methods have made many scientists and engineers distressed. Finally, after PFA was launched on the market, it received new enthusiasm in the plastics industry. This kind of performance is similar to PTFE material, has very good processing performance, so that engineers’ problems can be easily solved. While PFA materials are gradually being widely used, I also hope that scientists can develop more advanced and superior materials to meet market needs.

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-(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.

The structure and connection of the American standard valve

November 25, 2020

American standard valves mainly have API and ASME standards. ASTM and ASTM are material standards; valves designed, manufactured, produced and tested according to American standards are called American standard valves.
The American standard valve is a control component in the fluid conveying system. It has the functions of cut-off, regulation, diversion, prevention of reverse flow, voltage stabilization, diversion or overflow and pressure relief; the valve used in the fluid control system is cut off from the simplest American standard. There are many types and specifications of American standard valves used in extremely complex automatic control systems. Valves can be used to control the flow of various types of fluids such as air, water, steam, various corrosive media, mud, oil, liquid metal and radioactive media. Valve types: gate valve, knife gate valve, check valve, butterfly valve and others.

The structure types:

code	structure type	explaination	standard	face to face
C	BB-BG-OS&Y	bolted bonnet, bolted gland, outside screw & yoke	API602/API602M	ASME B16.10
D	BB-BG-OS&Y	bolted bonnet, bolted gland, outside screw & yoke	API603/API603M	ASME B16.10
E	BB-BG-OS&Y-N	bolted bonnet, bolted gland, outside screw & yoke-needle type	API602M	ASME B16.10
G	BC-PISTON-LIFT	(BOLTED BONNE,PISTON-LIFT)	API602M	ASME B16.10
H	BC-PISTON-LIFT	(BOLTED BONNE,PISTON-LIFT) outside screw & yoke	API603M	ASME B16.10
B	BB-BG-OS&Y-W	BOLTED BONNET,BOLTED GLAND,OS&Y ,BELLOWS SEAL TYPE)	API600M	ASME B16.10
L	BB-BG-OS&Y-L	BOLTED BONNET,BOLTEDGLAND ,OS&Y ,CRYOGENIC SERVICE SRRUCTURE	ASME B16.34	ASME B16.10
1	BC-SWING	(BOLTED BONNET,SWING)	API600M	ASME B16.10
2	PS-PISTON-LIFT	(PRESSURE SEAL BONNET,PISTON-LIFT)	API600M	ASME B16.10
3	WAFER TYPE	(WAFER CHECK VALVE)	API594	API594
4	TILTING-DISC	（TILTING-DISC TYPE CHECK VALVE）	API600M	ASME B16.10
5	BB-BG-OS&Y-F	(BOLTED BONNET,BOLTED GLAND,OS&Y,WITH SPECCIAL PACKING)	API600/API600M	ASME B16.10
6	BB-BG-OS&Y	(BOLTED BONNET,BOLTED GLAND,OS&Y)	API600/API600M	ASME B16.10
7	BB-BG-OS&Y-H	(BOLTED BONNET,BOLTED GLAND,OS&Y,WITH BLOMING HOLE)	API600/API600M	ASME B16.10
8	PS-BG-OS&Y	(PRESSURE SEAL BONNET,BOLTED GLAND,OS&Y)	API600/API600M	ASME B16.10
9	PS-COVER SWING	(PRESSURE SEAL BONNET, SWING)	API600/API600M	ASME B16.10
M	BB-BG-M-SEAL	PRESSURE SEAL BONNET,BOLTED GLAND,moving sealing	API600M	ASME 16.10

connection types:

code	connection type	explaination
S	SW	SOCKET WELDED
T	NPT	60° Taper pipe thread/NATIONAL TAPER PIPE THREAD
G	Rc	55° TAPER PIPE THREAD
R	RF	RAISED FACE
J	RJ	RING JOINT
W	BW	BUTT－WELDED
P	PIPE	EACH ENDWITH A 150mm SHORT PIPE
F	MF(F)	MALE-FEMALE FACE(FEMALE)
A	RF-NPT	one side RF, one side NPT

Tianjin Tanghai Valve Manufacturing Co., Ltd. is one of the largest butterfly valve manufacturers in China. It was founded in 2006. Its predecessor was Tanghai Valve Manufacturing Factory. Now we have our own independent R & D, manufacturing, assembly and warehousing workshops; we have professional pre-sale and after-sale technical support and perfect services.

Our products use advanced manufacturing technology, and strictly conform to API, DIN, BS, EN, ISO, GB and other international standards. The main products are butterfly valves, gate valves, check valves, globe valves, valve parts (Valve body, Valve disc, Valve shaft, Valve seat…), etc. Our products are widely used in various fields such as marine industry, shipbuilding, petrochemical, metallurgy, water treatment, fire fighting, water supply and drainage, etc. The company has won unanimous recognition and praise from customers with high quality and good reputation.

URL: http://www.tanghaivalve.com

Name: Harry Li

Email: harry@tanghaivalve.com

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