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How to replace valve packing for triple eccentric sealing butterfly valve

November 19, 2021

Although we are not focusing on valve packing during the procurement and use of triple eccentric butterfly valves, in fact packing has a great influence on the service life of the valve. If we find that the upper cavity is leaking during the pressure test, it is likely to be caused by the leakage of the packing. Wrong type of packing, packing leakage will cause internal leakage and greatly affect the service life.

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

There are many reasons for packing leakage. For example, the packing is the sealing effect of the pressure of the gland in the valve. After operation, the packing will age and become hard, especially the frequently used triple eccentric sealing butterfly valve, the friction between the valve stem and the packing is reduced, and it is easy to leak water and steam. At this time, the valve packing needs to be replaced. In normal times, we also need to regularly replace the valve packing through the investigation. Let’s take a look at how to replace the valve packing.
When replacing the packing for the triple eccentric sealing butterfly valve, for small valves with gland nuts, you can use a wire hook to clean the packing, put the asbestos rope clockwise around the valve stem and re-install the packing surface, and then tighten the gland nut. . Do not use excessive force when installing the nut to prevent tripping or breakage. If it still leaks after replacement, tighten it again until it does not leak. For large valves with flange glands, square or round asbestos ropes braided into strands can be cut into small sections according to the required length and laminated, and the joints of each layer should be staggered by 180°. When tightening the gland, the bolts on both sides should be compressed alternately to prevent the gland from breaking due to uneven force, and the rotation of the valve skewer should be checked to ensure the flexible rotation of the valve stem.
It is important to mention here that many developed countries do not allow the use of asbestos-containing valves. This is because asbestos has slight carcinogens, so triple-eccentric sealing butterfly valves with asbestos plates on the sealing surface are firmly not allowed to be used in drinking water. It can be considered to use full graphite or 314 or tetrafluoroethylene instead.
The triple eccentric sealing butterfly valve is widely applicable and easy to use. It has the advantage that it can be applied to a variety of working conditions by replacing the sealing pair, which is very popular. Need triple eccentric sealing butterfly valve, welcome to consult the brand manufacturer Tanghai Valve, who has rich experience in the production and processing of butterfly valve products, and there are many cases. I believe you will find your favorite products here.

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

How to choose the right butterfly valve (2)

July 13, 2020

However, the following problems still exist during the use of this butterfly valve:
1. Due to the multi-layer soft and hard laminated seal ring fixed on the valve plate, when the valve plate is normally open, the medium forms a frontal flush on the sealing surface. The soft sealing tape in the metal sheet interlayer is directly affected by the flushing, which directly affects the sealing performance.

U-type flange butterfly valve, ductile iron, DI, center line,

2. Restricted by structural conditions, the structure is not suitable for valves with a diameter of DN200 or less, because the overall structure of the valve plate is too thick and the flow resistance is large.
3. Due to the principle of the three-eccentric structure, the sealing between the sealing surface of the valve plate and the valve seat is caused by the torque of the transmission device to press the valve plate against the valve seat. In the positive flow state, the higher the medium pressure, the tighter the seal extrusion. When the medium in the flow channel reverses flow, as the medium pressure increases, the unit positive pressure between the valve plate and the valve seat is less than the medium pressure, and the seal begins to leak.

The high-performance triple-eccentric bidirectional hard seal butterfly valve is characterized in that the valve seat sealing ring is composed of multiple layers of stainless steel sheets on both sides of a soft T-shaped sealing ring. The sealing surface of the valve plate and the valve seat is an oblique cone structure. The surface of the oblique cone of the valve plate is welded with a temperature-resistant and corrosion-resistant alloy material; the spring fixed between the pressure plate of the adjustment ring and the adjustment bolt of the pressure plate are assembled together.
This structure effectively compensates the tolerance zone between the shaft sleeve and the valve body and the elastic deformation of the valve stem under medium pressure, and solves the sealing problem of the valve in the process of bidirectional interchangeable medium transportation. The use of soft T-shaped multi-layer stainless steel sheets on both sides to form a sealing ring has the dual advantages of metal hard seal and soft seal. It has zero leakage sealing performance at low and high temperatures.
The test proves that when the pool is in the positive flow state (the medium flow direction is the same as the disc rotation direction), the pressure on the sealing surface is generated by the torque of the transmission device and the effect of the medium pressure on the valve plate. When the positive medium pressure increases, the tighter the surface of the valve plate oblique cone and the valve seat sealing surface are pressed, the better the sealing effect. In the reverse flow state, the seal between the valve plate and the valve seat is pressed against the valve seat by the torque of the driving device. As the pressure of the reverse medium increases, the unit positive pressure between the valve plate and the valve seat is less than the medium pressure, the deformation energy stored by the spring of the adjusting ring after being loaded compensates the tight pressure of the sealing surface of the valve plate and the valve seat Play the role of automatic compensation. Therefore, unlike the prior art, the utility model does not install soft and hard multi-layer sealing rings on the valve plate, but directly installs on the valve body. It is an ideal two-way hard sealing method to add an adjustment ring between the pressure plate and the valve seat. . It will replace gate valves, globe valves and ball 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

How to choose the right butterfly valve (1)

July 13, 2020

When the butterfly valve is fully open to fully closed, it turns usually less than 90°. The butterfly valve and the butterfly stem itself have no self-locking capability. For the

U-type-flange-butterfly-valve-2

positioning of the butterfly plate, a worm gear reducer must be installed on the valve rod. The use of worm gear reducer can not only make the butterfly plate self-locking, stop the butterfly plate at any position, but also improve the valve performance. The characteristics of industrial special butterfly valve: can withstand high temperature, the applicable pressure range is also high, the nominal diameter of the valve is large, the valve body is made of carbon steel, and the sealing ring of the valve plate uses a metal ring instead of a rubber ring. Large high-temperature butterfly valves are manufactured by welding steel plates, and are mainly used for flue gas ducts and gas pipes of high-temperature media.

Selection:
The butterfly plate of the butterfly valve is installed in the diameter direction of the pipeline. The butterfly valve is simple in structure, small in size and light in weight. It is composed of only a few parts, and can be quickly opened and closed only by rotating 90°. The operation is simple, and the valve has good fluid control characteristics. When the butterfly valve is in the fully open position, the thickness of the butterfly plate is the resistance when the medium flows through the valve body. Therefore, the pressure drop generated by the valve is very small, so it has good flow control characteristics.

If the butterfly valve is required to be used as a flow control, the main thing is to choose the valve size and type correctly. The structural principle of the butterfly

wafer-type-butterfly-valve-with-handle-13

valve is especially suitable for making large-diameter valves. Commonly used butterfly valves are wafer-type butterfly valves and flanged butterfly valves. Wafer type butterfly valve is to use double-headed bolt to connect the valve between two pipeline flanges. Flange type butterfly valve is to use the process of connecting the flange of the valve to the pipeline flange with bolts.

The butterfly valve has been widely used in many fields such as petroleum, chemical industry, metallurgy, hydropower, etc. as a component used to realize the on-off and flow control of the pipeline system. In the well-known butterfly valve technology, the sealing form mostly adopts a sealing structure, and the sealing material is rubber, polytetrafluoroethylene and the like. Due to the limitation of structural characteristics, it is not suitable for industries such as high temperature, high pressure, corrosion resistance and wear resistance.

An existing more advanced butterfly valve is a three-eccentric metal hard-sealed butterfly valve. The valve body and valve seat are connected components. The sealing surface layer of the valve seat is welded with temperature-resistant and corrosion-resistant alloy materials. The multi-layer soft stack type sealing ring is fixed on the valve plate. Compared with the traditional butterfly valve, this butterfly valve has high temperature resistance, is easy to operate, and has no friction when opening and closing. When closing, the torque is compensated with the increase of the torque of the transmission mechanism, which improves the butterfly valve. The sealing performance and the advantages of extended service life.

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

How to achieve internal and external anti-corrosion of pneumatic valves

July 2, 2013

Pneumatic valve using pneumatic actuators, for which Air (or other gas) pressure is the source of power. Air pressure acts on the piston or bellows diaphragm, which produces a linear force on the valve stem. Pneumatic actuator is a kind of Power-operated actuators (using pneumatic, hydraulic or electric power), can remotely adjust valves, or quickly operate large valves.

In order to effectively guarantee the use efficiency of the pneumatic valve, and also to effectively extend the service life of the pneumatic valve, the internal and

Pneumatic actuator (2)

external corrosion protection of the pneumatic valve is a very important part of its use process, then we should pay attention to the main points for the internal and external corrosion protection of the pneumatic valve And what are the main items in the operation, we will give a brief introduction to you in the following article.

1. The inside of the valve body of the pneumatic valve and all parts of the valve plate require comprehensive corrosion protection. On the one hand, it will not rust in water, and there will be no electrochemical corrosion between the two metals; on the other hand, the smooth surface reduces the resistance to water.

2. Hygienic requirements of epoxy resin or paint for anti-corrosion of pneumatic valve body shall have a test report from corresponding authority. The chemical and physical properties should also meet the relevant requirements.

3. The inside and outside of the valve should first be shot blasted to remove sand and rust, and strive to

pneumatic valve structure

electrostatically spray powdered non-toxic epoxy resin with a thickness of more than 0.3mm. When it is difficult to electrostatically spray non-toxic epoxy resin for extra large valves, similar non-toxic epoxy paint should also be brushed and sprayed.

In addition, the pneumatic valve should also pay attention to the necessary maintenance during daily storage and transportation, including:

1. The pneumatic valve should be stored in a dry and ventilated room, and both ends of the passage must be blocked.
2. Valves stored for a long period of time should be checked regularly to remove dirt and apply anti-rust oil on the processed surface.
3. After the pneumatic valve is installed, regular inspections should be carried out. The inspection items are as

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

follows:
1) The wear of the sealing surface;
2) Trapezoidal thread wear of the stem and stem nut;
3) Whether the packing is out of date and invalid, and if damaged, it should be replaced in time.

TH Valve is one of the largest butterfly valve, check valve manufacturers in China. 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.

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

How to replace valve packing for triple eccentric sealing butterfly valve

How to choose the right butterfly valve (2)

How to choose the right butterfly valve (1)

How to achieve internal and external anti-corrosion of pneumatic valves

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