Adhesive wear

Adhesive wear is usually caused by sliding between metals. As the two pieces of metal are pressed together, the uneven surfaces come into contact with each other to form contact points. As they slide, the joints break to form new junctions that eventually form abrasive particles. The wear of materials will increase the dimensional tolerance of parts, which will result in leakage and damage to the valve closing mechanism. Moreover, the debris, especially large particles formed by abrasion or adhesion, will jam the moving parts of the valve and disable it.

Abrasive wear

Abrasive wear occurs when hard particles cut materials under load. Hard particles such as sand, alumina, carbides, etc. press the surface of the soft metal under normal loading, and a trench will be drawn to form metal detritus or orange-thinning debris when sliding.

Erosive wear

Erosion wear is a special form of abrasive wear caused by the cutting action of particles suspended in the fluid under the action of kinetic energy. It will occur on valves used to feed ancient solids, such as closed funnel valves used to transport mud or in blast furnace feed systems.

Corrosive wear

If the worn surface is subjected to chemical corrosion, corrosion wear will occur. Most corrosion-resistant alloys initially form a protective layer of solid chemical corrosion, which may be worn away as the surface slides, and the metal exposure to surrounding corrosive media increases wear rates.

Surface fatigue wear

The phenomenon of surface fatigue wear can be observed when closed track is sliding or rolling repeatedly. Because the cracks on the part’s surface or surface-f expand under repeated cyclic stress, fatigue wears usually forms a pit on the surface. Surface fatigue wears generally occur in rolling elements such as bearings, gears, and other parts.

Besides the above wear types, there are some special wear types such as fretting wear, corrosion, and cavitation.

Fretting wear or corrosion

Fretting wear is caused by the vibration of tiny tangents that produce oxide wear debris, so the oxide causes further wear just like an abrasive grain.

Cavitation

Cavitation occurs when a sudden change in pressure causes the liquid to drag within. It appears on the hydrofoil, steam valves, and steam transparency parity. The mechanical impact of the bubble’s collapse causes holes to form on the metal surface, and this wear is usually avoided by properly designing the valve to minimize pressure drop. Steam globe valves are usually prone to this abrasion. Although the design is unavoidable and some cobalt-base gold can be used as part material to reduce steam corrosion, the cost of the valve has increased.

Conclusion

There are different types of wear, and some engineers may induce wear purposely for varying reasons.

Thank you for reading our article and we hope it can help you better understand the 7 types of wear produced during valve operation. If you want to learn more about sanitary valves, we would like to advise you to visit Adamant Valve homepage for more information.

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Especially the urea pipeline valve, because of its relatively high temperature and corrosion, stuffing is prone to aging. Enhanced maintenance can extend the service life of the stuffing.

2. In order to ensure the elasticity of the stuffing, when sanitary valve is ready to be out of the factory, a pressure test is conducted under static conditions to make sure there’s no leakage.

When the valve is installed in the pipeline, due to temperature and other factors, the leakage might happen. When leakage happens, we must tighten the nuts on both sides of the stuffing lid of the valve. Tighten the nuts once again if leakage happens again Do not tighten the nuts to the extreme so as not to make the stuffing lose elasticity and sealing performance.

3. Some valve stuffing contains molybdenum disulfide lubricant. After several months of use, appropriate lubricating grease should be timely added to the stuffing. When there’s a need to increase the amount of stuffing, corresponding stuffing should be timely added to ensure the sealing performance of the valve.

4. During the opening and closing process of the valve, the original lubricating oil will continue to drain. Coupled with the temperature, corrosion, and other factors, the lubricating oil will continue to dry. So we need to constantly check the transmission parts of the valve. Once a lack of oil is found, we should timely replenish it to prevent the failures such as increased wear, inflexible transmission, and being stuck due to lack of lubricant.

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Tracing the history of the development of the solenoid valve, so far, it can be divided into three categories according to its mechanism. These are direct-acting type, distributed direct-acting type, and pilot type. And according to the differences in the structure of the valve flap, materials, and mechanism, they can be divided into six sub-categories.

They are direct-acting diaphragm structure, distributed diaphragm structure, pilot diaphragm structure, direct-acting piston structure, distributed direct-acting piston structure, and pilot piston structure.

Direct-acting solenoid valve

Mechanism:

When the power is on, the electromagnetic coil generates electromagnetic force to lift the closing member from the valve seat and the valve opens. When the power is off, the electromagnetic force disappears, and the spring presses the closing member onto the sanitary valve seat, and the valve closes.

Features:

It can normally work in a vacuum, negative pressure, and zero pressure situation, but the diameter is generally less than 25mm.

Distributed direct acting solenoid valve

Mechanism:

It is a combination of direct-acting type and pilot type. When there is no pressure difference between the inlet and outlet, after the power is on, the electromagnetic force directly lifts the pilot valve and closing member of the main valve upwards successively, and the valve opens. When the starting pressure difference is achieved between the inlet and outlet, after the power is on, the pressure in the lower chamber of the pilot valve and main valve rises, while the pressure in the upper chamber drops, so the pressure difference pushes the main valve open; when the power is off, the pilot valve pushes the closing member down using the force of the spring or the pressure of the medium to have the valve closed.

Features:

It can act reliably in zero pressure difference, vacuum, and high-pressure situations. But the power is relatively large, and it must be horizontally installed.

Pilot solenoid valve

Mechanism:

When the power is on, the electromagnetic force opens the pilot hole and the pressure in the upper chamber decreases rapidly, forming a pressure difference around the closing member. The fluid pressure pushes the closing member to move upward, and the valve opens; when the power is off, the force of the spring closes the pilot hole, forming a pressure difference around the closing member with the inlet pressure rapidly passing through the bypass hole. The fluid pressure pushes the closing member to move downward, and the valve closes.

Features:

The upper limit of the fluid pressure range is high, and it can be installed in any position while meeting the requirements of fluid pressure difference.

Conclusion

A solenoid valve is used to open, close, mix, or divert media in an application. They are used in a wide variety of applications from dishwashers, cars, and irrigation. Thank you for reading our article and we hope it can help you better understand the mechanism and structure of the solenoid valve. If you want to learn more about solenoid valves, we would like to advise you to visit Adamant Valve homepage for more information.

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Shielding effect

When a coating is applied to a metal surface, the metal surface is relatively isolated from the environment, so this protective effect can be called shielding. However, it must be pointed out that a thin layer of paint cannot play an absolute shielding role.

Polymers have certain permeability, and the average diameter of their structure pores is generally 0.000005cm-0.0000000cm, while the molecular diameter of water and oxygen is usually only a few angstroms, so they are free to pass through when the coating is very thin. Therefore, both the soft seal gate valve and the soft seal butterfly valve have strict requirements on the epoxy coating thickness of the surface.

In order to improve the impermeability of the coating, the film-forming material with small permeability and solid filler with large shielding should be chosen as the anticorrosive coating, and the number of coating layers should be increased to make the coating reach a certain thickness and compact without holes. For example, when the molecular chain of the polymer is less branched, more polar genes, and the cross-linking density of body structure is large, the air permeability is small.

A coating pinhole is formed in the process of coating, so it is closely related to the amount of solvent and volatile properties, the nature of the film-forming material, and construction conditions. After comparing the water permeability and air permeability of several coatings with different coating thicknesses, it can be seen that the anti-seepage ability of the coating is greatly improved when it increases to 0.3-0.4mm.

Corrosion inhibition

The internal components of the coating react with the metal to passivate the metal surface or create a protective material to enhance the protective effect of the coating on the specially required valve. Besides, the cast steel gate valve used in the pipeline can also act as an organic corrosion inhibitor under the action of some oil and drying action of metal soap.

Electrochemical protection

When the dielectric permeable coating touches the metal surface, it will form electrochemical corrosion under the film. The use of metal with a higher activity than iron, such as zinc, as the filler in coatings, can be sacrificial anode protection. In addition, the corrosion product of zinc is basic zinc chloride and zinc carbonate, which will fill the gap of the film, make the film compact, greatly reduce corrosion and extend the service life of the valve.

The post What are the Effects of the Coating on the Valve Surface? appeared first on Adamant Valves.

Balancing of heating and cooling systems is performed to ensure that the correct amount of water is present at all consumption points. Balancing is carried out by building balancing valves into the system, thereby adding adjustable resistance.

What are the top 6 precautions to take when installing balancing valves?

1. Differential pressure-balancing valve should be installed on the return pipe. The valve is connected to the pressure pipe. The other end of the pressure pipe is connected to the water supply pipe. It is recommended to install a 1/2″ sanitary ball valve at the water supply side of the pressure pipe so as to enable congestion elimination function.

2. The medium flow direction of the differential pressure-balancing valve should be consistent with the direction of the valve body arrow.

3. Filters should be installed on the water supply pipe in front of the pressure pipe to prevent the valve from losing automatic adjustment function due to poor water quality.

4. Pressure gauges should be installed on the water supply pipe of the differential pressure balancing valve and the return pipe in front of it to make it easy for regulation and control of the pressure difference.

5. If the system flow is too large or too small for the differential pressure-balancing valve, the possible reason is that the debris produced when installing pipe fittings is stuck in the valve plug. In this case, we can close the 1/2″ ball valve for 3-5 minutes. If the blockage is not severe, it’ll disappear automatically. If the blockage persists, we need to disassemble the valve to remove the debris.

6. Way to control pressure difference: Adjust the valve stem counterclockwise to observe the pressure difference.

Conclusion

Thank you for reading our article and we hope it can help you better understand the top 6 precautions to take when installing balancing valves. If you want to learn more about balancing valves, we would like to advise you to visit Adamant Valve homepage for more information.

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When you take a closer look, you’ll find that every residential and industrial pipeline system would immediately fail without functioning valves, leading to floods, environmental disasters, and collapsing supply chains. Our society and economy truly depend on valves of all types to prevent these catastrophes. For these reasons, manufactured valves undergo rigorous regulation and testing before installation, ensuring they’ll function safely and dependably.

Contrary to what you might think, valve core sealing components have complex requirements to ensure proper performance and longevity. In fact, the valve manufacturing process is complicated and technically sophisticated, especially the stainless steel sanitary valves used in food and drug production lines. There are many obstacles and difficulties to overcome throughout the process of valve manufacturing. If you’re curious about how sanitary valves are made, we’ll break down the sanitary valve manufacturing process into three comprehensible points. 

How are valves manufactured?

1. The complex valve blank manufacturing and inspection process

Valve castings are formed by heating metals to thousands of degrees Fahrenheit, at which point they melt into liquids. The liquid metals are poured into molds, where they cool and take the shape of a specified valve.

Valve cast blanks are structurally complex, thin-walled shell parts. Valve casting blanks are required to have a smooth surface, a clear character casting, and integral density. In order to meet the above requirements, a series of processing measures should be taken during casting, such as the selection of high refractory molding material and the control of sand moisture, the layering during molding to ensure the hardness of the sand, the use of reasonable casting cap systems and strict control of pouring speed and temperature. Due to its high technical requirements, the casting process of the valve blank is far more complicated than that of general castings.

The finished valves are initially inspected for proper size, position accuracy, and appearance. Then, they are inspected more closely for microstructure, mechanical properties, corrosion resistance, and non-destructive probing. Even the valve inspection, testing process, and quality assurance steps of manufacturing are rather complicated and exhaustive.

2. Valve Installation on Machine Tools

The structure and shape of the main parts of the valve are very complex. Some parts are thin-walled and slender, with poor rigidity. When they are machined with industrial tools, positioning and clamping can be very difficult, and complicated special fixtures are often needed.

For some sanitary valve parts, the positioning base has low accuracy and high surface roughness. Sometimes even non-machining surface positioning is used. But there are very high requirements for the accuracy and surface roughness of the processed sealing surface, so it’s very hard to ensure the processing quality. Therefore, to meet the processing needs, it is often necessary to increase the accuracy of the positioning base and reduce the surface roughness, or to produce a positioning surface on a non-processing surface, which only increases the complexity of the valve manufacturing process.

3. Complex Mechanical Processing

Due to the wide variety of valve materials, except for various cast iron and carbon steel, the shearing performance of most high strength, corrosion-resistant, and high-hardness materials is very poor, making it difficult to achieve the specified machining accuracy and surface roughness. And there are very high requirements for the geometrical precision and surface roughness of the sealing surface of the valve, so it’s even more difficult to perform mechanical processing on valves. Meanwhile, the poor shearing performance of valve materials causes quite a few new problems for the processing methods, cutting tool materials, excessive shearing, and valve processing equipment.

Conclusion — Essential Valve Manufacturing

Valve manufacturing is not as simple as we thought. There are several complex issues to overcome when building a capable and dependable valve. The high requirements for valve sealing during the manufacturing process ensure that it is not prone to leakage during use. These critical pieces of equipment are truly essential to manufacturing, storing, and transporting a massive number of products across our economy. If you want to learn more about how valves are made, please visit Adamant Valves for more information.

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Working pressure and temperature

Generally speaking, the higher the pressure and temperature of the sanitary valve, the worse the working conditions will be. In order to ensure the safety and reliability of the valve, the pressure bearing parts and pressure controlling parts of the valve needs to have sufficient strength, especially the properties of materials at high temperature and low temperature, such as thermal strength, oxidation resistance, thermal stability and impact toughness of materials at low temperature.

The sealing surface material is also required to have good abrasion resistance, abrasion resistance, corrosion resistance, erosion resistance, etc. since the high-pressure medium passes through the density surface quickly and the erosion is serious.

Different forms and materials must be selected according to the characteristics of medium, temperature, and working pressure to guarantee the sealing performance of packing and gasket. In the valve that operates in a corrosive medium, all pressure and pressure control parts (including gaskets and packing materials) in contact with the medium should be stable enough to withstand the chemical action of the medium. Otherwise, the service life of the valve will not be long enough to meet the requirements.

Pressure and temperature fluctuations can cause poor sealing conditions on the joint flange, as the joint bolts and gaskets will be deformed when the working pressure and working temperature are high.

When the working pressure and working temperature decrease, the gasket will lose its sealing performance due to insufficient compressive force, and such periodic fluctuations also affect the material properties of the parts, so fluctuations in working pressure and working resistance are extremely adverse to the working conditions of the valve.

Mechanical characteristics of the driving devices

Each drive has its own stress characteristics, which are related to different specific pressures on the sealing surface, as well as stress on the stem and stem nuts and other parts. When the electric device is closed to the endpoint, the impact load is applied to the sealing surface, especially the sanitary globe valve. In sanitary relief valves, the sealing surface is also impacted by spring and hammer when the disc resets, which worsens the sealing surface and affects the service life of the valve to varying degrees.

Working conditions

Working conditions are poor when sanitary valves are installed and used outdoors. Since the valve is prone to rust and sometimes even damage the lubrication after being exposed to the rain and wind, the wear of the parts will be accelerated if dust and sand fall on the joint of the parts of the valve.

If the valve is installed at sea, the working environment of the valve is even worse. The valve as a whole will be soaked by chlorine ions in the salt fog, and it will rust easily and lose the function of the valve itself. Therefore, the selection of valve material to be considered resistant to chloride ion corrosion, and should also pay attention to the surface of the paint.

If the valve is installed in the ground, the valve with the lengthened all-welded belt should be selected to avoid damage to the connecting parts and moving parts of the valve after it is buried in the groundwater and sand.

In order to guarantee the service life of the sanitary valve, the structure of the valve and the material of the main parts must be selected according to the working conditions, otherwise, the service life of the valve will be reduced.

At the same time, the maintenance of the valve should be strengthened in the process of operation, such as regular removal of dirt, regular lipid injection, regular maintenance, etc., to extend the service life of the valve.

The post What Does the Operating Condition of Sanitary Valves Depend? appeared first on Adamant Valves.

There will be scratches, bumps, crushes, and other damages during the opening and closing of the sealing surface. Between two sealing surfaces, under high temperature and high pressure, there will be mutual penetration of atoms, resulting in adhesion. When the two sealing surfaces move along each other, they’re prone to be torn apart at the adhesive point. The higher the surface roughness of the sealing surface, the more likely such phenomenon is going to happen. During the closing process of sanitary valve and returning process of valve flap, there’ll be bumps and crush to the sealing surface, leading to partial wear or indentation of the sealing surface.

The erosion from the medium:

It’s the result of wear, rinse, and cavitation to the sealing surface by the medium. At a certain speed, the planktonic particles inside the medium are in contact with the sealing surface, causing partial damage. Medium in high speed directly flushes the sealing surface, causing partial damage. When the mixed flow of medium and partial vaporization happen, impact strikes the sealing surface, causing partial damage. The erosion from the medium, combined with chemical erosion, will strongly erode the sealing surface.

Electrochemical erosion:

The contact between sealing surfaces, the contact between the sealing surface and valve body, the medium concentration difference, and oxygen concentration difference can all lead to potential difference and the occurrence of electrochemical erosion, causing the anode side of the sealing surface to erode.

Chemical erosion from the medium:

The medium near the sealing surface, under the circumstances of no electrical current, directly has a chemical effect on the sealing surface, eroding the sealing surface.

Improper installation and poor maintenance cause the sealing surface to malfunction. With the valve malfunctioning, the sealing surface is prematurely damaged.

Damage caused by improper selection and poor handling:

Valves are not selected according to the working conditions. Shut-off valves are used as throttle, resulting in very quick closing and lax closing, making the sealing surface erode and wear.

Poor quality of processing of sealing surface:

There are cracks, stomata, ballast, and other defects on the sealing surface. These are caused by improper selection and poor handling of welding and heat-treatment processes. If the hardness of the sealing surface is too high or too low, it’s usually because of improper selection or heat treatment. If the hardness of the sealing surface is uneven, and the sealing surface is not corrosion-resistant, it’s usually because the bottom-level metal is blown up to the surface during the welding process, diluting the alloy composition of the sealing surface.

Conclusion

Thank you for reading our article and we hope it can help you better understand the causes leading to damaged valve sealing surface. If you want to learn more about the causes leading to damaged valve sealing surface, we would like to advise you to visit the Adamant Valve homepage for more information.

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Hydraulic control valves are used to adjust the flow rate of hydraulic fluid in a hydraulic system. These valves have a port that is able to be adjusted so that the flow area may be changed to provide an alteration in the flow rate through the valve.

How Does a Hydraulic Control Valve Work?

Within a hydraulic system, a flow-control valve will be used to control the rate of flow to hydraulic cylinders and motors, which in turn will impact the speed of both of those devices. Hydraulic flow-control valves also have a secondary function of managing the energy transfer rate at a specified pressure.

1. What is the hydraulic control valve?

The hydraulic control valve is a kind of valve that is controlled by water pressure. It consists of the main valve and other accessories such as conduit, pilot valve, needle valve, sanitary ball valve, and pressure gauge.

2. What are the types of hydraulic control valves?

According to different purposes of use, functions, and occasions of use, there are remote control float valves, pressure relief valves, slow-closing check valves, flow control valves, hydraulic electric control valves, and water pump control valves. According to the structure, it can be divided into diaphragm type and piston type.

3. The diaphragm type hydraulic control valve mechanism VS piston type hydraulic control valve

The diaphragm type and piston type hydraulic control valve share the same mechanism.

They both use the pressure difference between upstream and downstream as power. They are controlled by a pilot valve to make the diaphragm (piston) perform the hydraulically differential operation, which is completely automatically adjusted by hydraulic power so that the main valve disc is fully open or fully closed or in the regulatory state. When the pressure water entering the upper control chamber of the diaphragm (piston) is discharged to the atmosphere or downstream low-pressure zone, the pressure on the bottom of the valve disc and diaphragm is larger than the pressure on the top, pushing the main valve disc to fully open position.

When the pressure water entering the upper control chamber of the diaphragm (piston) can’t be discharged to the atmosphere or downstream low-pressure zone, the pressure on the top of the valve disc and diaphragm is larger than the pressure on the bottom, pushing the main valve disc to the fully closed position.

When the pressure in the upper control chamber of the diaphragm (piston) is between the inlet pressure and outlet pressure, the main valve disc is in a regulated state and its position of adjustment depends on the joint control effect of the needle valve and adjustable pilot valve of the conduit system. The adjustable pilot valve can use the downstream outlet pressure to enlarge or tighten the valve opening, thereby changing the pressure value in the upper control chamber of the diaphragm (piston) and controlling the adjustment position of the main valve disc.

Conclusion

Thank you for reading our article and we hope it can help you better understand the mechanism of the hydraulic control valves. If you want to learn more about hydraulic control valves, we would like to advise you to visit Adamant Valve homepage for more information.

The post What is a Hydraulic Control Valve Mechanism? appeared first on Adamant Valves.

The coating is the most widely used anti-corrosion means, especially in sanitary valve products is an indispensable anti-corrosion material and identification sign. The coating is usually made of synthetic resin, rubber slurry, vegetable oil, and solvent, covering the metal surface, insulating medium, and atmosphere, achieving the purpose of anti-corrosion. The coating is mainly used in water, salt water, seawater, or atmosphere where corrosion is not very strong.

Corrosion inhibitor

Corrosion inhibitor controls corrosion by promoting polarization of the battery. The corrosion inhibitor is mainly used in the medium and filler, which is added to the medium to slow down the corrosion of equipment and valve.

Cr-Ni stainless steels are active in a large range of sulfuric acid-free from oxygen and have serious corrosion. However, adding a small number of oxidants such as copper sulfate or nitric acid can turn the stainless steel into a blunt state, forming a protective film on the surface to prevent the erosion of the medium.

In hydrochloric acid, the corrosion of titanium can be reduced by adding a small amount of oxidant. Valves are often tested with water, which tends to corrode the valve. Adding a small amount of sodium nitrite to the water prevents water from corroding the valve.

Asbestos packing contains chlorides, which are highly corrosive to the stem, and distilled water scrubbing reduces the chloride content. However, this method is much more difficult to implement and is not suitable for the general application, but only for special needs.

Electrochemical protection

Electrochemical protection is divided into anode protection and cathode protection.

Anodic protection means that the anodic potential increases in a positive direction with the input of the protective metal and direct current. When it increases to a certain value, a compact protective film is formed on the surface of the metal anode, that is, passivation film. At this time, corrosion of metal cathode decreases sharply. Anode protection is suitable for metals that are easily passivated.

Cathodic protection means that the protected metal is used as a cathode, and the negative potential is reduced by adding a direct current. When it reaches a certain potential value, corrosion current velocity decreases, and the metal is protected. In addition, cathodic protection can be protected by a metal whose electrode potential is more negative than the metal being protected. If zinc is used to protect iron and zinc is corroded, then it is called sacrificial metal.

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