Knowledge Archives

How many types of gate valves?

July 19, 2021

Types and classifications method of gate valves
Gate valve, also called slab valve, is mainly composed of valve body, bonnet, gate, valve stem, valve seat and sealing packing. It is one of the most common valve types in isolation valves. The main purpose of the gate valve is to cut off the fluid. For this reason, it is usually called a “cut off” valve or a “blocking” valve. There are many different structural forms of gate valves, and the types of sealing elements used in them are different. According to the

Socket ended resilient seated wedge gate valve-ductile iron (1)

structure of the sealing element, it can be divided into several different types.
Classified by valve stem:
According to the stem type, it can be divided into bright stem gate valve and dark stem gate valve. The valve stem is the operating part of the gate valve, and its function is to transmit the opening and closing force to the opening and closing parts.
1. The trapezoidal thread of the stem of the rising stem gate valve is placed outside the valve body and located on the upper part of the valve stem. By rotating the stem nut, the valve stem drives the gate plate to rise and fall synchronously to realize the opening and closing of the valve, so it is easy to identify the valve. Open and close state to avoid misoperation. Since the stem nut is outside the body cavity, it is conducive to lubrication, and the opening and closing state is intuitive and obvious, so it is widely used. However, in harsh environments, the exposed threads of the valve stem are susceptible to damage and corrosion, even affecting operation. Its disadvantage is that the height of the valve after opening is large, and a stroke is usually added to the original height of the valve, which requires a lot of operating space.
2. Dark stem gate valve is also called rotating stem gate valve (also called dark stem wedge gate valve). The stem nut is placed inside the valve body and is in direct contact with the medium. It is often fixed on the gate. Through the rotation of the valve stem, the valve stem nut drives the gate to move up and down to complete the opening and closing. Usually there is a trapezoidal thread at the bottom end of the valve stem. Through the thread at the bottom end of the valve and the guide groove on the valve disc, the rotary motion is changed into linear motion, that is, the operating torque is turned into operating thrust. Since the trapezoidal thread used for transmission is located inside the valve body, it is easily corroded by the medium and cannot be lubricated. The opening degree cannot be directly observed, and an indicating device is required. However, its valve stem does not move up and down, and requires a small operating space, so it is suitable for occasions with limited locations and dense pipelines.

gate valve (3)

Classified by structure:
According to the structure type, it can be divided into two types: wedge gate valve and parallel gate valve. That is, a wedge-type gate valve is called a wedge gate valve, and a parallel gate valve is a flat gate valve.
1. The flat gate valve means that the sealing surface is parallel to the vertical centerline, so the sealing surface of the valve body and the gate plate are also parallel to each other. The most common type of this kind of gate valve is the double gate type. In order to make the valve body and the two sealing surfaces of the gate closely contact when closed, a double-sided thrust wedge is often used between the two gates. Most of them are used on low-pressure pipelines such as small pipelines. Parallel gate valves using single gates are also rare but rare.
2. Wedge gate valve means that the sealing surface is at a certain angle to the vertical centerline, that is, the two sealing surfaces are wedge-shaped gate valves. The wedge gate valve has single and double gate plates. The advantage of the double gate type is that the accuracy of the sealing and the angle is lower, the temperature change is not easy to make the gate wedged, and the sealing surface wear can be compensated with gaskets. The disadvantage is that the structure is complex, and it is easy to stick in dry media, and the main reason is that the upper and lower baffles are easy to fall off after years of corrosion.
Classification by other methods:
According to different standards: national standard gate valve, American standard gate valve, German standard gate valve, Japanese standard gate valve
According to the connection method: flanged gate valve, welded gate valve, threaded gate valve (divided into internal thread and external thread)
According to pressure level: high pressure gate valve, low (medium) pressure gate valve According to driving mode: electric gate valve, pneumatic gate valve, manual gate valve
Classified by material: stainless steel gate valve, forged steel gate valve, cast steel gate valve, carbon steel gate valve, cast iron gate valve, copper gate valve (also divided into bronze gate valve, brass gate valve), ceramic gate valve, plastic gate valve

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

Globe valve structures and design standard

July 15, 2021

Globe valve structure, Globe valve design standard
The shut-off valve is a particularly common shut-off valve, which is mainly used to connect or cut off the medium in the pipeline, and is generally not used to adjust the flow. The globe valve is suitable for a wide range of pressure and temperature, but it is generally used for medium and small diameter pipelines.

Globe valve (2)

Globe valve (1)

Globe valve (9)

Structural principle of globe valve:
1. The center of the inlet and outlet of the shut-off valve are on the same straight line, and the fluid flows like an S-shaped sphere, so it is also called a spherical shut-off valve.
2. When the valve seat of the valve stem descends toward the bottom sealing surface and is pressed down, the medium stops flowing; when the valve stem rises, the medium passes through the flow path from below to above.
Globe valves generally have direction requirements during installation. The flow direction of the medium in the pipeline generally flows from bottom to top through the valve seat port, which is what we often call the so-called “low inlet and high outlet”. The purpose of this is to reduce fluid resistance and save effort in opening. In the closed state, the valve stem and the packing culvert are not in contact with the medium to ensure that the valve stem and the packing culvert are not damaged or leaked.

Globe valve structure diagram Globe valve structure and design standards:

name	Globe valve structure	Globe valve design standard
Typical Forged Steel Globe Valve	1. Flow channel JB/T 7746-1995: Shrinkage hole BS5352-1999: Through hole or shrinkage hole (CL150~800); Through hole (Cl1500) JPI-7S-36-1999: Through hole 2. Valve body and bonnet Connection: flange, thread or welding 3. Connection end JB/T 7746-1995: internal thread, socket welding or flange BS5362-1999: internal thread, socket, flange and butt welding JPI-7S-36- 1999: Internal thread, socket	JB/T 7746-1995 BS 5352-1999 JPI-7S-36-1999
Internal pressure self-sealing forged steel globe valve	1. Flow path: shrinkage hole 2. Connection between valve body and bonnet: internal pressure self-sealing 3. Connection end: butt welding, flange or socket	ASME B16.34-1996
Cast steel globe valve	1. Flow path: angle type, straight-through, direct current (Y type) 2. Connection between valve body and bonnet: flange 3. Connection end: flange or butt welding 4. Various types of discs can be used, Usually exposed rod, there are also a few smaller diameter valves with dark rod	JPI-7S-46-1999 JIS B2071-1999 JIS B2072-1999 JIS B2081-1999 JIS B2082-1999 BS 1873-1999 MSS-SP-42-1999 GB/T 12235-1989 BS 5160-1989
Bellows Sealed Globe Valve	1. Flow path: angle type, straight-through, direct current (Y type) 2. Connection between valve body and bonnet: flange 3. Connection end: flange or butt welding 4. Various types of discs can be used, It is usually an exposed stem, but there are also a few valves with smaller diameters that use double stem seals with concealed stem 5, bellows and packing	ASME B16.34-1996
Angle type high pressure globe valve	1. Flow path: angle type 2. Connection between valve body and bonnet: thread, clamp or welding 3. Various types of discs can be used. For ultra-high pressure valves, internal pressure self-balancing discs are usually used 4. The valve body can adopt integral type, two-piece type 5. Connection end: flange or butt welding	ASME B16.34-1996 GB/T 12235-1989
Lining stop valve	1. Flow channel: angle type, straight-through, direct current (Y type) 2. Connection between valve body and bonnet: flange 3. Connection end: flange or butt welding 4. Lining material is rubber, plastic, etc.	ASME B16.34-1996
Two-way three-way globe valve	1. Flow path: two-way three-way flow path 2. Connection between valve body and bonnet: flange 3. Connection end: flange or butt welding	ASME B16.34-1996
Cast steel discharge stop valve	1. Flow path: straight-through 2. Connecting end: flange 3. Disc: upward or downward expansion 4. Connection between valve body and bonnet: flange	ASME B16.34-1996
Three-way globe valve	1. Flow path: Tee 2. Connecting end: Flange 3. Disc: Plane seal	ASME B16.34-1996
Pressure gauge shut-off valve	1. Flow path: DC, right angle, three-way 2. Connection between valve body and bonnet: integral forging or thread 3. Connection end: external thread, clamp 4. Disc: Cone and flat	ASME B16.34-1996
Water seal stop valve	1. Flow path: DC 2. Connection end: socket welding, butt welding 3. Valve body and bonnet: both forged, with a chromium nickel steel or carbon steel 4. Disc: Cone seal (DN10~25mm) , Plane seal (DN32~200mm)	E101-1999 GB/T 12235-1999 ASME B16.34-1996
Slurry shut-off valve	1. Flow path: DC 2. Connection end: Flange 3. Valve body structure: The valve seat is clamped between the left and right valve bodies, and the left and right valve bodies are connected by bolts. 4. The valve body and the bracket are connected by bolts. 5. The valve cover: CL150 is forged as a whole, CL300 and CL400 are split type, using strut connection. 6. Disc: Cone surface is sealed into plane seal, or throttle type sealing surface is overlaid with hard alloy	GB/T 12235-1989 ASME B16.34-1996
Angle globe valve	1. Flow path: right angle 2. Connection end: flange 3. Valve body and bonnet: forged throttling type. The sleeve is drilled and the piston moves up and down in the sleeve to adjust the flow. 4. Valve body, valve Cover connection: bolt connection	API 6A-2002
Titanium Globe Valve	1. Flow path: straight-through 2. Valve body, bonnet, stuffing box, valve clack, valve stem are made of titanium 3. Valve body and bonnet connection: bolt connection 4. Valve clack is flat seal	GB/T 12235-1989

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

Structural characteristics & features of flanged butterfly valves

July 8, 2021

The basic knowledge and structural characteristics of flange butterfly valves:
The flanged butterfly valve has introduced a self-sealing design concept, in which the connection between the disc and the valve shaft adopts a patented pull-out pin structure. The main features of the valve are reliable sealing, bi-directional sealing, and tight connection without loosening, so that the valve can be used for a long time. Its characteristics are as follows:

Double flange butterfly valve (16)

Two-way sealing
Generally, traditional butterfly valves cannot be sealed well under the working pressure in the opposite direction (not conducive to the sealing direction) due to their structural reasons. At present, the relevant national standards do not have mandatory regulations for two-way sealing. This is because:
1. Adopting the self-sealing design concept. The disc sealing ring is directly embedded in the disc in a zigzag shape with rubber, and there is no need to use pressure rings or bolts to fix, thus avoiding the uneven force of the sealing ring caused by the traditional bolt pressure plate type seal, which makes the bolts The problem of falling off and premature damage to the sealing ring. Under the action of the working pressure in the opposite direction, the sealing ring generates self-sealing force, which increases the specific pressure of the seal. The sealing ring compresses the valve seat. The greater the working pressure in the opposite direction, the greater the self-sealing force, so that the sealing ring and the valve seat The combination is tight to achieve the effect of two-way sealing.

triple offset butterfly valve-double flange- (4)

2. The disc has good rigidity and is not easy to deform. The disc of butterfly valve above DN300 is a double-plate truss flow-through structure, with small flow resistance and good rigidity. Under the working pressure in the opposite direction, it is not easy to deform, so that the sealing ring will not follow the disc Deformed and separated from the best sealing point of the valve seat, thus ensuring the sealing effect of the sealing ring.
3. Long life of rubber sealing ring
(1) Due to the self-sealing design concept, the small interference between the rubber ring and the stainless steel valve seat only maintains the initial seal, so the specific pressure required for the seal increases with the increase of the system pressure.
(2) In addition, there is a so-called “breathing” groove for rubber elastic retreat in the zigzag groove, so that the rubber has a certain expansion space when it is under pressure, so that it will not produce elastic fatigue during long-term work, so it is sealed The life of the ring is greatly increased compared with the traditional type.
Patent design withdrawal pin structure
Usually in the process of using the butterfly valve, due to the traditional pin connection, the pin passes through the center of the valve shaft, which not only reduces the strength of the valve shaft, but also creates a gap between the valve shaft and the valve shaft during long-term use, which will cause an impact when the valve is opened and closed. Load, this load is much greater than the load generated by the extrusion stress and shear stress under normal conditions. Often the pin is severely deformed or broken during use, which makes the valve closed or fails, and greatly reduces the valve Service life. If the newly produced valve adopts the US patent design withdrawing pin structure to replace the pin connection structure between the shaft and the valve disc, the withdrawal pin does not pass through the center of the valve shaft, not only does not weaken the strength of the shaft, but also connects with the valve shaft. The fitting surface is greatly increased. By tightening the withdrawal pin nut, a pre-tightening force is generated between the withdrawal pin and the valve shaft joint surface, so that the disc valve shaft is tightly combined without gaps, and it will not be used when opening and closing the valve. The impact load is generated, so that the valve flap rotates smoothly, thereby realizing reliable sealing.
Unique design of the bottom axial adjustment and locking device
In butterfly valves above DN300, considering the reliability of the self-weight seal of the butterfly plate, the position of the disc on the valve seat is in the best sealing state through precise adjustment and fixation of the axial position during manufacturing. For the sagging of the valve clack that may be caused during long-term use, it is also convenient to further adjust the lock to achieve zero leakage in long-term use.
Easy to replace the sealing ring
When the sealing ring needs to be replaced, there is no need to remove the disc, just open the valve fully, and then take out the key from the operating device, after the operating device is adjusted to the closed state, it still maintains the key connection with the main valve, and then continues in the opening direction Turn the hand wheel until the sealing ring is on the side of the valve body sealing surface to replace the sealing ring.
Related knowledge: the principle of butterfly valve structure
Related products: Electric flanged butterfly valve Pneumatic flanged butterfly valve

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

structures and differences of Non-rising stem(NRS) and rising stem(RS) gate valve

July 8, 2021

structures and differences of Non-rising stem(NRS) gate valve and rising stem(RS) gate valve
RS gate valve structure picture, NRS gate valve structure picture

rising stem gate valve-OS&Y

RS gate valve and NRS gate valve are different from the transmission mode. RS gate valve is a handwheel that drives a nut to rotate in place, and the stem is linearly raised and lowered to complete the switch; NRS gate valve is a handwheel that drives the stem to rotate, and there are threads in the gate. Nut) to move up and down to complete the switch.

Structural principle of gate valve:
1. NRS gate valve structure: The stem nut is in the valve body and is in direct contact with the medium. When opening and closing the gate, it is realized by rotating the valve stem.
2. RS gate valve structure: the stem nut is on the bonnet or bracket. When opening and closing the gate, the stem nut is rotated to realize the lifting of the stem.
The difference between RS gate valve and NRS gate valve:
1. RS gate valve can see the screw, but NRS can not see the screw;
2. The RS gate valve raises or lowers the disc through the threaded transmission of the valve stem and the steering wheel; when the NRS gate valve is switched on and off, the steering wheel and the valve stem are connected and relatively immobile. It drives the valve through the rotation of the valve stem at a fixed point. The flap is lifted up and down to complete the opening and closing;

non-rising-stem-gate-valve-IS&Y

3. The transmission thread of the NRS gate valve is located inside the valve body. During the opening and closing process, the valve stem only rotates, and the gate is raised and lowered in the valve body; the valve stem of the RS gate valve drives the gate to rise and fall together, and the drive thread on the valve stem Outside the valve body, the opening and closing and position of the gate can be intuitively judged according to the movement direction and position of the valve stem;
4. The height of the NRS gate valve is small; the RS gate valve requires a larger installation space;
5. The structure of the RS gate valve is beneficial to the lubrication of the valve stem, and the degree of opening and closing is obvious; the thread of the valve stem of the NRS gate valve is not only unable to be lubricated, but it is directly corroded by the medium and is easily damaged. Therefore, the RS gate valve is more widely used.

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 Globe Valve

July 7, 2021

Principle of Pneumatic Globe Valve, Working Principle of Pneumatic Globe Valve
Working principle of pneumatic stop valve:
Pneumatic shut-off valve is a valve that uses compressed air as the power source. It adopts remote control. The main control room manually or automatically triggers the action command to activate the inlet and exhaust solenoid

pneumatic globe valve

valves to supply and discharge compressed air into the actuator. Compressed air acts on the piston or diaphragm to overcome the frictional force of the valve action and the spring force on the valve stem, thereby depressing (for the loss of air to open the valve) or lifting (for the loss of air to close the valve) the valve stem, driving the valve core to move up and down , Make the valve open or close. When the valve loses air and there is no compressed air in the drive head, the valve will be in a safe position of fully open or fully closed according to the requirements of the system. Compressed air for power plant instruments, the supply pressure is generally 4-9bar. Before entering the valve, the compressed air is first filtered and purified through the filter, and then reduced by the pressure reducing valve. The reading of the inlet pressure gauge does not exceed 4bar. Pressure adjustment can be achieved by adjusting the adjustment screw installed on the top of the pressure reducing valve, and the protective cover must be loosened before adjustment.
Pneumatic globe valve installation instructions:
Pneumatic shut-off valve is usually used in fully closed and fully open gas and liquid unidirectional flow pipelines. It has a longer structure and shorter length than gate valves. When the medium is highly corrosive, a low-inlet and high-outlet stop valve should be used. When the medium pressure is high or the valve stem is frequently opened and closed, the valve stem should be thickened to avoid bending of the valve stem caused by the thrust of the medium. Compared with other valves, the flow resistance of the pneumatic shut-off valve is larger. Pay attention to the problems of the air source pressure and the pressure and corrosion resistance of the valve stem during use. Pneumatic shut-off valve is not suitable for media with particles, high viscosity and easy to coke.

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

Ventilation butterfly valve installation instructions

July 5, 2021

Ventilation butterfly valve installation | instructions for use
Instructions for use of the ventilation butterfly valve:
The structural design of the ventilation butterfly valve should be combined with the operating conditions of the valve.

ventilation butterfly valve (2)

1. Under the smelting conditions with high temperature and high dust content, the design of the ventilation butterfly valve can adopt a flat inclined plate structure. There is a gap between the butterfly plate and the valve body of this structure. The gap value is based on the valve diameter and workmanship. The operating conditions are determined, and generally controlled within 0.5% of the channel area, which can meet the requirements of the ventilation butterfly valve installation, temperature changes in working conditions, and melting process requirements. To
2. Under the condition of high temperature and low dust content, the design of the ventilation butterfly valve can adopt the vertical plate structure. The sealing surface of the structure is easy to process, and the gap value of the sealing surface is controlled within 0.2% of the channel area. The dimensional accuracy of the valve body and butterfly plate sealing pair can meet the design requirements through mechanical processing.
3. For working conditions with high temperature, low pressure and strict sealing requirements, the design of the ventilation butterfly valve adopts a lever-type plane structure. The sealing pair preparation and butterfly plate running track can meet the technological requirements of high sealing performance pipe network equipment.
The main body seal of the ventilation butterfly valve selects different structures according to different working conditions, which is conducive to the production and use of the valve. The shaft end structure design of the ventilating butterfly valve adopts an external support structure with excellent heat insulation and sealing effects, which can realize the function of sealing the second shaft end of the valve and then supporting it, which is convenient for adjustment, and will not cause shaft end jam. When the direct connection or the crank connecting rod mechanism is connected with the transmission mechanism, the installation of the heat insulation sleeve can effectively keep away the influence of the high temperature environment on the transmission device and ensure the normal operation of the valve. The valve body and butterfly plate of the large-diameter ventilating butterfly valve should be cast or welded according to the requirements of the working conditions, and ribs should be configured, and reasonable process plans and materials should be selected to improve the rigidity of the product and prevent product deformation.
Precautions for installation of ventilation butterfly valve:
The installation position of the ventilation butterfly valve in the pipe network and the pipe network layout also affect the use of the valve. The closed funnel is designed at the opening end of the valve or the corner of the valve connection for the pipe with large smoke and dust. Regular dust removal can prevent excessive dust accumulation, which is beneficial The rotation of the butterfly board. There are several issues that should be paid attention to when installing the ventilation butterfly valve.
1. The use of metal gaskets must ensure that the load is uniform, and avoid the additional pressure of the valve due to the influence of temperature and self-weight or the stress caused by welding, and the deformation of the valve flange and pipeline.
2. When the valve is installed in a place with a long pipeline, a support frame should be installed.
3. The valve installation should pay attention to the medium flow direction, so that the opening direction of the butterfly plate is consistent with the pipeline medium flow direction, which is beneficial to the self-cleaning effect of the medium flow rate.
4. Strengthen the protection of the overall insulation layer of the pipe network so that the pipe wall temperature is above the dew point, which can reduce the low-temperature cohesive dust accumulation. If the pipe wall temperature is higher than the acid dew point of the flue gas, the condensation of acid vapor on the heated pipe wall can be avoided, and the generation rate of sulfur trioxide can be controlled, and the valve will be more effective. To
The installation position of the ventilation butterfly valve varies according to the design of the pipeline, such as horizontal, vertical and angled. Generally, vertical pipe installation of the ventilation butterfly valve has a better effect and is not easy to accumulate dust, followed by horizontal pipes, and has the worst effect at angles. The turning points on both sides of the valve inlet and outlet are most likely to form drift and ash blockage, and the valve operating torque will increase.
Related Products: Electric Ventilation Butterfly Valve Pneumatic Ventilation Butterfly Valve

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

Butterfly valve flange types and introduction

June 28, 2021

Butterfly valve flange introduction, butterfly valve flange types
Butterfly valve flanges are called flanges and flanged parts. It is a product that connects valves and pipes in pipelines. The special flanges for butterfly valves are the same as ordinary flanges, that is, the inner hole is different. The special flange of the butterfly valve has a small inner hole and an extra slot for intubation.

flange TG-

The butterfly valve flange can be a single type or a combined type, such as the flanges at both ends of the valve, which is convenient for installing bolts. One end of the pipe and the other end are flange-to-flange connection, or a connection joint, which refers to a foldable connection that is connected to each other by flanges, gaskets and bolts as a set of combined sealing structures. Pipe flanges refer to pipe installations. The flange used in the middle piping, the valve refers to the flange of the valve, the flange has holes, bolts make the two flanges tightly connected, and the flange is sealed with gaskets.
[Butterfly valve flange material] No. 20, A105, Q235A, 12Cr1MoV, 16MnR, 15CrMo, 18-8, 321, 304, 304L, 316, 316L.
[Sealing surface form] Flat surface (FF), raised surface (RF), convex surface (M), concave surface (F), concave and convex surface (MF), tenon surface (T), groove surface (G), tongue and groove surface (TG) , Ring connection surface (RJ).
[According to petrochemical industry standards] Threaded flange (PT), butt welding flange (WN), flat welding flange (SO), socket welding flange (SW), loose flange (LJ), flange cover ( No note).
[According to mechanical industry standards] Butterfly valve flange pictures: Integral flange, butt welding flange, plate flat welding flange, butt welding ring plate loose flange, flat welding ring plate loose flange, flange ring plate loose flange method Lan, flange cover.
[According to national standards] Integral flanges, threaded flanges, butt welding flanges, flat welding flanges with necks, socket welding flanges with necks, butt welding ring loose flanges with necks, plate flat welding flanges, Welded ring plate loose flange, flat welded ring plate loose flange, flanged ring plate loose flange, flange cover.
[According to chemical industry standards] Integral flange (IF), threaded flange (Th), plate flat welding flange (PL), diameter butt welding flange (WN), neck flat welding flange (SO), bearing Insert welding flange (SW), butt welding ring loose flange (PJ/SE), flat welding ring loose flange (PJ/RJ), lining flange cover (BL (S)), flange cover (BL ).
Related products: 7types of flange sealing surface; Pneumatic flanged butterfly valve

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 structure and characteristics of bellows gate valve

June 24, 2021

The structure and characteristics of bellows gate valve
The valve stem of the bellows gate valve adopts a double sealing structure of bellows and packing to ensure a leak-free seal at the valve stem. It is used in power stations, natural gas, ammonia, vacuum, refrigeration systems, hot oil, and hot water systems. It is especially suitable for flammable, Pipelines for explosive, toxic and precious media.

rising stem gate valve-OS&Y (3)

Bellows gate valve structure:
The bellows, bonnet and stem of the bellows gate valve are welded into one body without seams, so there is no leakage. The action of the valve stem is caused by the deformation of the compressed bellows, not by relative movement. Ordinary gate valves are sealed with packing, the valve stem and packing will slide, and it is easy to leak (spool) at low temperatures. Bellows gate valves do not have this problem.
Structure diagram of bellows gate valve
Bellows gate valves use stainless steel hermetic bellows that can be stretched and compressed instead of packing seals. They are generally used for the transmission of more permeable media, such as valves on hydrogen systems. As long as the bellows are not damaged, there is generally no leakage; while general gate valves Packing is used for sealing, which is prone to leakage.
Features of bellows gate valve:
1: The corrugated gate valve is double-sealed, bellows (stainless steel) + packing, and has better safety performance, so it is often used in systems such as toxic media, flammable and explosive media, high-temperature steam, and hot oil.
2: The switching torque is small, the switching is relatively easy, there is no flow resistance loss, the service life is long, and the appearance is beautiful. Related knowledge: Working principle of gate valves Types and classifications of gate valves

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
related news /knowledge: Comparison of bellows globe valve and ordinary globe valve; Fasteners, fillers and gasket materials of valves;

pneumatic fluorine-lined butterfly valve vs pneumatic hard-sealed butterfly valve

June 16, 2021

The difference between pneumatic fluorine-lined butterfly valve and pneumatic hard-sealed butterfly valve
Pneumatic butterfly valve is an important execution unit with relatively large usage in industrial pipelines. Compressed air is used as the power source to operate the valve opening and closing, and the execution speed is very fast, usually only a few seconds! Pneumatic butterfly valve has simple structure, convenient operation and low cost. It can not only be used for quick shut-off, but also can be matched with valve positioner to receive relevant signals to achieve adjustment and control of pipeline medium pressure, flow, temperature and other parameters!

D673H-16C-stainless steel pneumatic triple eccentric butterfly valve

There are many types of pneumatic butterfly valves, which can fully meet the requirements of various working conditions, and can also customize the required butterfly valve products according to customer needs. Pneumatic fluorine-lined butterfly valve and pneumatic hard-sealed butterfly valve are two commonly used types. The medium and pressure temperature used are different. The control mode of the two is the same, but the sealing structure is completely different. Pneumatic fluorine-lined butterfly valve is suitable For pipelines that require sealing and contain corrosive media, but the pressure and temperature should not be too high, pneumatic hard-sealed butterfly valves can be used in various pressure and temperature ranges, with long service life, but poor sealing effect!

1. From the structure:
The hard sealing butterfly valve refers to that both sides of the sealing pair are made of metal materials or other harder materials. For soft sealing butterfly valves, the two contacting sealing surfaces can be separate or all of soft materials. For example, fluorine-lined butterfly valve means that the butterfly plate and valve seat are both wrapped in PTFE;
2. From the sealing performance:

Fluorine lined butterfly valve-PTFE-WAFER (8)

The advantage of soft-sealed fluorine-lined butterfly valve is good sealing performance, but the disadvantage is that it is easy to age, wear, and has a short service life. The hard seal butterfly valve has a long service life, but the sealing performance is relatively worse than that of the soft seal.
3. From the conditions of use:
The soft-sealed fluorine-lined butterfly valve is used in normal temperature and pressure environment, and the hard-sealed butterfly valve can be used in low temperature, normal temperature, high temperature and other environments. Generally, it can be used for higher pressure, but the soft seal is not. However, the fluorine-lined butterfly valve has super corrosion resistance!
4. From the manufacturing point of view:
As for manufacturing, from a principle point of view, there is little difference between the two, mainly the difference in valve seats. The soft-seal fluorine-lined butterfly valve is a non-metallic structure, and the hard-seal butterfly valve is a metal structure. The hardness relationship between metals and the workmanship must be considered. Situation, what medium to go and so on. The choice between pneumatic fluorine-lined butterfly valve and pneumatic hard-sealed butterfly valve is mainly based on the process medium, temperature and pressure. Generally, the medium contains solid particles and is worn, or the temperature is higher than 200 degrees. It is best to choose hard-sealed butterfly valves!
Related knowledge: Pneumatic butterfly valve working principle diagram; Pneumatic butterfly valve model compilation method

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

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