flanged butterfly valve Archives

Instructions for the safe use of resilient seated flanged butterfly valves

December 6, 2021

The resilient seated flanged butterfly valve has the characteristics of small opening torque, flexibility and convenience, labor-saving and energy-saving. The sealing form of the soft seal has reliable performance and can achieve no leakage. Therefore, the use of flange soft-seal butterfly valve is very wide, and it has its presence in all major pipeline systems, and its safe use has gradually attracted attention.

Double flange butterfly valve (16)

First of all, the safety of the valve piping system must first consider the main valve. A soft-seal flanged butterfly valve is required to be used as a safety master valve. The function is to cut off and connect the entire pipeline system. In normal production, it is also in the normally open state. The main valve is generally not used to adjust the flow rate and should be installed at the inlet of the main pipeline.
Secondly, a main valve is also needed at the inlet of the branch pipeline. The butterfly valve here is mainly used to control the branch pipeline safely. In addition to the cut-off function, the main valve of the branch pipeline also has the function of adjusting the flow rate. Adjust the flow rate to meet the needs of the branch pipeline flow size, and strictly follow a certain ratio, which is adjusted and controlled by the main valve of each branch pipeline. There should be two flanged soft-seal butterfly valves or safety valves that are often switched on or off or used for adjustment. One of the butterfly valves is spare and is normally open and not in use. A spare valve can be used if there is a problem with the working butterfly valve, so that it will not affect the production. After repairing, a butterfly valve is still reserved as a spare.
On liquid and gas pipelines, a safety drain valve is required at the lowest point or at a suitable place. The function is to empty the medium blocked in the pipeline to avoid air resistance in the pipeline. Because the gas in the pipe will reduce the pipe section, increase the transmission resistance, reduce the flow rate, and affect production. For some special liquids that will dissolve gas after a certain period of time and cannot be discharged during operation, it is also necessary to drain the butterfly valve.
The closing of the resilient seated flanged butterfly valve also has safety requirements. After the valve is closed tightly, some media will also change as the temperature changes, and the thermal expansion of the valve components will increase the pressure between the butterfly valve and the valve seat. When it is turned on again, it will inevitably bring difficulties. Therefore, the torque required to open the valve will be greater than the torque required to close the valve. The resilient seated flanged butterfly valve needs to overcome the increase of static friction due to the increase of the pressure between the sealing surfaces due to the temperature change. Because of the friction between the sealing surfaces, when the valve is closed and opened again, the required torque is much larger than the torque required to close the 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

Video of center-lined butterfly valve: https://youtu.be/NuSZH_AJcwY

Comparison of the characteristics of wafer butterfly valves and flanged butterfly valves

November 4, 2021

To find out what is the difference between the wafer butterfly valve and the flange butterfly valve, let’s take a look at the comparison of some characteristics of the wafer butterfly valve and the flange butterfly valve.

Wafer type butterfly valve with worm gear

The biggest difference is of course that the flanged butterfly valve has two more flanges, and the wafer type has two fewer flanges. Of course, the price is cheaper, and the price is about 2/3 of the flange. Flange butterfly valves are more reliable than wafer butterfly valves. Wafer butterfly valves are not as convenient as flanged butterfly valves in installation, because they need to be equipped with flanges, which can easily leak if they are not installed well.

From the perspective of specific working conditions, when selecting imported valves, use wafer-type butterfly valves as much as possible, which are light in weight and easy to replace. However, the length of the bolts of the wafer butterfly valve is longer, and the construction accuracy is higher. If the flanges on both sides are not aligned, the bolts will be subjected to greater pressure and the valve is prone to leakage. Under high temperature conditions, the bolts of the wafer butterfly valve may cause leakage after expansion, so if it is under high temperature conditions, the wafer butterfly valve is not suitable for large pipe diameters. In addition, wafer butterfly valves generally cannot be used at the end of the pipeline and downstream where it needs to be disassembled, because when the downstream flange is disassembled, the wafer valve will fall off. In this case, a short section must be made separately. For disassembly. The wafer butterfly valve has no flanges at both ends of the valve body, only a few guide bolt holes, and the valve is

Double flange butterfly valve (17)

connected with the flanges at both ends by a set of bolts/nuts. Compared with flanged butterfly valves, it is easier to disassemble. The cost of the valve is lower, but the disadvantage is that one sealing surface has a problem, and both sealing surfaces have to be disassembled. Regarding the blue butterfly valve, the above problem does not exist, and of course it has to pay a higher cost. But the cost will be higher.

The flange type butterfly valve has flanges at both ends of the valve body, which are connected with pipe flanges. The seal is relatively more reliable.
In addition to selecting the appropriate wafer butterfly valve or flange butterfly valve, attention should also be paid to the installation and maintenance of the butterfly valve. Because this is actually a place that can affect the selection of the valve outside of the specific purpose. Let’s take a look at the specific requirements below:
1. The valve disc stops at the closed position during installation.
2. Determine the opening position according to the rotation angle of the butterfly plate.
3. For the butterfly valve with bypass valve, the bypass valve should be opened before opening.
4. Ask professionals to install according to the manufacturer’s instructions, especially the heavy butterfly valve should be fixed.
5. The butterfly plate of the butterfly valve is installed in the diameter direction of the pipeline. In the cylindrical passage of the butterfly valve body, the disc-shaped butterfly plate rotates around the axis, and the rotation angle is between 0° and 90°. When rotated to 90°, the butterfly valve is fully open.
The butterfly valve is used as a flow control, the main thing is to choose the size and type of the valve when purchasing. Butterfly valves are not only widely used in general industries such as petroleum, gas, chemical, and water treatment, but also used in cooling water systems of thermal power stations.

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

Correct installation of flanged butterfly valve can effectively prevent leakage

September 28, 2021

Butterfly valve has the advantages of good flow adjustment function and good closing and sealing characteristics, so it has become one of the fastest-growing valve varieties in the past ten years. It has simple and compact structure, light weight, convenient operation, reliable performance, complete functions, beautiful appearance, easy

Double flange butterfly valve (16)

maintenance, and is very popular with customers. In actual working conditions, if you want the flanged butterfly valve to achieve effective leakage prevention, the correct installation method is very important. Today, the editor of Tanghai Valve will share with you the installation precautions of the flange butterfly valve, as follows:
1. Before installation, you must carefully check whether the valve’s logo and certificate meet the requirements for use, such as Tanghai D342X flange rubber-sealed butterfly valve, to see whether the product brand, model, etc. are consistent with the valve required for the pipeline, and clean it after verification. Here is also the storage problem of flanged butterfly valves: the butterfly valves that have not been installed and used for the time being must be stored in a dry room; the butterfly valves that have been stored for a long time should be cleaned regularly, blown dry, and coated with anti-rust oil. The flange sealing surface should be protected by a blind plate.
2. Install according to the medium and its flow direction. For example, if you use water, you need to use ethylene-propylene rubber gaskets. When tightening the bolts, use the symmetrical or star-shaped torque method; if you use corrosive media, use PTFE gaskets. When tightening the bolts, use Torque on symmetrical or star-shaped method;
3. When installing the connecting bolts of the flange butterfly valve and the pipeline, do not tighten a single piece at one time, and should tighten it in diagonally opposite directions multiple times to prevent the uneven force from leaking at the flange connection.
4. When installing the butterfly valve, keep the butterfly plate in the closed position to prevent debris from entering the worn sealing surface. When the user is testing pressure, the pressure can be tested only after the two ends are installed with flange pairs.
5. When the valve is connected to the pipeline, flanges of appropriate specifications should be selected to ensure an effective sealing surface.
6. Before the electric flange butterfly valve is connected to the power supply for the first time, it needs to be manually adjusted to 1/3 of the closed position, and check whether the direction of the indicator plate is consistent with the opening direction of the valve.
7. When the flange butterfly valve is in use, if any malfunction is found, it should be stopped immediately.
Master the above correct installation method, flange butterfly valve will be more confidential and durable in application. If you are in need of purchasing high-quality flanged butterfly valves, Tanghai will be your best choice. The sealing surface of Tanghai flange butterfly valve has high processing precision, small opening friction and easy closing. Not only the self-sealing performance and the sealing performance are stable, but it also has the characteristics of self-locking that becomes tighter and tighter. It is suitable for gas, steam, air, water and other media. You are welcome to inquire.

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

Posts

Instructions for the safe use of resilient seated flanged butterfly valves

Comparison of the characteristics of wafer butterfly valves and flanged butterfly valves

Correct installation of flanged butterfly valve can effectively prevent leakage

Structural characteristics & features of flanged butterfly valves

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