What are bellows valves
Bellow valves are a type of valve that use a flexible bellow element to control the flow of fluids or gases. The bellow element is typically made of metal or other durable materials and is designed to expand and contract in response to changes in pressure or temperature. This movement allows the valve to open or close, regulating the flow of the fluid or gas through the system. Bellow valves are commonly used in applications where precise control of flow is important, such as in chemical processing, pharmaceutical manufacturing, and other industrial settings.
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A Bellows Valve is a specially designed valve suitable for use in industries dealing with a hazardous medium where even minute leakages can be extremely critical. With the exponential growth of new industries such as the chemical and nuclear industry, there is a growing abundance of flammable, hazardous, extremely poisonous, and toxic media flowing through the pipelines. This creates a high risk of leakage, explosion, and health hazards. So, the valves used in such pipes and systems have specific stringent leakage and sealing requirements.
What is the costruction of bellows seal valves
A bellows valve is a type of industrial valve that uses a bellows element to create a hermetic seal. The construction of a bellows valve typically includes a valve body, a bonnet or cover, a stem, a handwheel or actuator, and the bellows element itself.The bellows element is typically made of metal, such as stainless steel, and is designed to flex in response to changes in pressure or temperature. This flexibility allows the bellows element to compensate for thermal expansion and contraction, as well as pressure fluctuations, while maintaining a tight seal.The stem of the valve connects the handwheel or actuator to the valve disc or plug, which is used to control the flow of fluid or gas through the valve body. The bonnet or cover is used to protect the internal components of the valve, including the bellows element and stem, from external damage or contamination.Overall, the construction of a bellows valve is designed to provide reliable and precise control of fluid or gas flow while maintaining a hermetic seal to prevent leaks or contamination.Bellows seal valves are a type of industrial valve that use a flexible metal bellows to create a hermetic seal between the valve stem and the valve body. They are commonly used in applications where leakage cannot be tolerated, such as in chemical processing, pharmaceuticals, and food and beverage production.There are several types of bellow seal valves, including:1. Globe valves2. Gate valves3. Check valves4. Ball valves5. Butterfly valvesEach of these types of valves has its own unique design and characteristics, but they all use a bellows seal to prevent leakage and ensure reliable operation.
Advantages of Bellows Seal Globe Valve
1. The most prominent advantage of any bellows valve is the Double seal design (bellows + packing). So, even if the bellows fails, the stem packing will prevent any kind of leakage to meet the international sealing standards.
2. It minimizes any loss of medium fluid and ensures the safety and environmental protection. This will ultimately improve the safety of the plant where is bellows valve has been installed.
3. It can act as an energy saver as it contributes to minimizing energy losses due to leakage.
4. Since the leakage is minimized, it prevents frequent maintenance of the valve. So, it leads to longer valve life.
5. Owing to longer service life, operating and maintenance cost is considerably reduced.
6. The rugged bellows seal design ensures zero leakage from the valve stem, thereby providing the maintenance-free conditions.
7. The safety of working personnel is improved with the installation of a bellows valve as emissions of inflammable, toxic, and hazardous chemicals can be minimized.
The difference between common valve and bellows seal valves
Bellows globe valves and common valves are two types of valves used in industries to control the flow of fluids or gases.
The main difference between these two types of valves is that bellows globe valves have a bellows assembly that separates the fluid or gas flowing through the valve from the valve stem, whereas common valves do not have this feature.
When valves with gland packing are used such as gate valves or ball valves in the system for heated oil transfers (permeability of heated oil is about 50 times that of steam), chances of hot oil spillage are quite high and can cause loss of equipment and property. In such cases, due to its construction, the bellows valve can ensure absolutely nil leakage.
In ordinary valves, the shape of graphite packing cannot provide 100% effective sealing which is the main reason for frequent leakage of packing valve. As ordinary fillers are manufactured with graphite, if the purity of graphite is not adequate, its oil resistance would below. When heating oil being transferred is soaked in a graphite filler, certain graphite impurities get separated and flows along with it.
When a ball valve is used in the system with heated oil, if the internal PTFE is not resistant to high temperatures, it will quickly deteriorate and cause valve leakage.
The internal parts of the bellows valve are made of stainless steel, which can withstand a temperature of 425°C. Considering the life span of Bellows Seal Globe Valve, the duration of the general bellows valve is more than three years. Therefore, to maintain the reliability of output and to reduce the direct running costs, a bellow shut-off valve is preferred over ordinary seal valves in case of a system where heated oil is being transferred.
The bellows assembly is made of a series of convoluted metal plates that expand and contract with changes in pressure or temperature, allowing the valve to operate smoothly and without any leaks.
In contrast, common valves rely on a packing material, such as graphite or PTFE, to prevent leaks around the valve stem. This packing material can wear out over time, leading to leaks and increased maintenance costs.
Overall, bellows globe valves are generally considered to be more reliable and longer-lasting than common valves, especially in applications where leakage is not acceptable.
Selection Guide for Bellows
1. Choose the inner diameter of the bellows according to the diameter of the valve stem. The inner diameter of the bellows should be greater than the stem diameter of 115 mm.
2. The outer diameter of the bellows is selected according to the inner diameter of the bellows. The outer diameter and the inner diameter are related by the ratio of the outer diameter to the inner diameter. In general, the ratio of the outer diameter to the inner diameter is 113 to 115.
3. The wall thickness, number of layers, number of corrugrtions, and length of the corrugated pipe must meet the requirements of the pressure resistance, stroke, and cycle life of the corrugated pipe. Under normal circumstances, greater the pressure, more thickness of the bellows is required. To increase the displacement or reduce the stiffness of the bellows and increase life, the thickness of the single layer can be reduced and the number of layers of the bellows can be increased.
4. For handling higher pressures, the multiply design of bellows is recommended. The pressure that bellows can withstand can be increased by using 2 or 3 piles of the metal wall as in case of multiply design of bellows. Pressure rating by using a two-ply bellow can increase by 80% to 100% than single-ply bellow of the same thickness. Alternately, the stroke length is reduced if single-ply bellow of a thickness equivalent to the pressure rating of two ply bellow is used. So, we get a distinct advantage of multiply design over the single-ply thick bellows.
5. To prevent the distortion of bellows, the designed guide structure must be strictly followed.
6. To prevent wear and premature failure, local contact between the valve stem or bellows must be avoided.
7. The design should be such that twisting and torsional deformation of the bellows is prevented.
8. The valve design should be limited by the extension stroke and compression of the bellows. This is to prevent displacement of the bellows and to withstand compression and tensile extension beyond the defined cycle life test. Under normal conditions, the stroke of the bellows should not exceed 25% of the free length. If this is not fulfilled, it will affect the cycle life of the bellows, especially bellows valves under high temperature and high-pressure environment.
9. The bellows adopt the same pressure and temperature grade as the Bellow seal Globe Valve. The bellows must withstand the pressure test of the nominal pressure of the main valve at 38 ℃ and 115 times the nominal pressure at 38 ℃. During the pressure test, the weld should not crack or leak, and the bellows should not twist.
10. The material of the bellows components should be selected within the allowable temperature range, and it should have good formability, welding performance, and compatibility with the medium.
Application range of Bellows Seal Globe Valve
· Bellows valves eliminate the risk of leakage of the process fluid and are therefore ideally suited for applications where leakage cannot be tolerated from the valves. So, places where highly hazardous materials such as hydrogen, ammonia, chlorine, and other similar poisonous or explosive material are handled, these valves are preferred.
· It is suitable for use as a shut-off valve with heat-conducting oil, toxic, flammable, highly permeable, environmentally polluting, and radioactive fluid pipelines. It can be considered as a high-quality product for creating a leak-free factory.
· To name a few, bellows seal globe valve is highly used in petrochemical industries, electronics industry, various plants, vacuum industries, etc.
Precautions for Bellows Seal Globe Valve
Ø To avoid damage or injury to personnel or equipment, always read all warnings and instructions. Unprofessional re-conditioning, the use of foreign replacement parts, or the incorrect maintenance steps, may cause a loss of efficiency or lead to personnel injury or damage to parts.
Ø Use double seal bellows in case of a highly corrosive chemical environment so that you get two protective layers of sealing.
Ø If you find that there is a smell of media in the air or the valve cover is wet, it is generally because the bellows have been damaged by the medium.
Ø You can replace the bellows by yourself or get it replaced by makers. Replace it to avoid prolonged negligence, a threat to life, and damage to the entire valve.
Ø An excessively tightened gland nut can cause excessive packing wear and can hinder the free movement of the plug stem.
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Reasons for Leakage of Bellow Seal Glove Valve
There are many reasons for the leakage of a Bellows Seal Valve. Bellows valve leakage is generally divided into internal leakage and external leakage.
1. It is because the liquid medium contains solid impurities that damage the sealing surface and cause failure.
2. Combined with the analysis of the on-site usage, the reason for the leakage of the valve stem is mainly related to the valve structure, working environment, and operation mode.
3. The valve stem adopts a double sealing structure of bellows and packing. The bellows are welded with the inner lining ring and the outer lining ring to form a bellows assembly and then welded with the valve stem and the guide body to block the leakage of the medium through the valve stem. The valve stem of the bellows valve moves up and down by the flat key, until the upper-end surface of the flat key contacts the lower end surface of the lower packing. Since the lower packing is made of PTFE material, if the valve is opened too much, the flat key will be embedded in the packing, the bellows valve can no longer be opened and closed, and the bellows assembly is knocked to death, causing the medium to leak along the valve stem.
4. Tensile elongation and compression of the bellows valve according to the line determination process can contribute to leakage. If tension or compression exceeds the limit, the bellows may be damaged, resulting in small series hose rupture, seal failure. Therefore, it is necessary to increase the limit device for opening and closing of the bellows valve, so that the bellows always expand and contract within the design range during the operation of the valve.
Summary
The unique design of Bellows Seal Globe Valve and its efficiency to provide leak-proof operations makes it the best-suited valve for a wide range of applications, especially hazardous materials & where system media is at high temperatures. Durability, maintenance-free operations and cost-effectiveness is an added benefit with bellows valves.
A bellows seal globe valve is an essential component in many industries, such as chemical, oil and gas, and petrochemical industries. It is a type of industrial valve used to regulate and control the flow of fluids, gases, and other media through a pipeline or system. These bellows valves are widely used because of their unique design, which includes a bellows seal that protects the stem from corrosion and prevents fluid from eroding the stem. So it’s very common to see the condition for corrosive or toxic media.
globe valvesThe bellows seal globe valve consists of body, disc, stem, bonnet, bellows seal, and packing. The valve body is the primary component that houses the valve disc, which controls the flow of media. The valve stem connects the valve disc to the actuator or handwheel, which opens or closes the valve. The bonnet covers the stem and packing and the bellows valve provides a seal to prevent leakage. The following is the photo of bellow seal globe valve.
din globe valve with bellowsNo.Parts Name Materials1BodyGS-C25/1.0619CF8/1.4301CF8M/1.44082SeatOverlay 13CrSS304SS3163Disc surfaceOverlay 13CrSS304SS3164StemX20Cr13SS304SS3165BellowsSS304/SS316/SS321/SS316T1SS304/SS316/SS321/SS316HSS316/SS321/SS3167I6GasketGraphite+SSGraphrte+SSGraphite+SS7Bellows coverSS304ZSS316SS304/SS316SS3168BonnetGS-C25/1.0619CF8/1.4301CF8M/1.44089NutA194 2HA194 8A194 8M10BoltA193 B7A193 B8A193 B8M11 PackingGraphiteGraphiteGraphite12Glandc.sCF8CF8M13PinSteelSteelSteel14Guide pieceSteelSteelSteel15Stem nutDuctile ironCopper alloyCopper alloy16Grease NippleH2H2H217Hand wheelSteelSteelSteel18Lock nutA105A105A105There are several types of bellows seal valves and globe valves available in the market, each with unique design features and applications. Here are some of the most common types of bellows seal globe valves:
This type of valve has welded metal bellows that provides a flexible, leak-proof seal and protects the stem from corrosion. Welded ends bellows seal globe valves are ideal for high-temperature and high-pressure applications.
This type of valve has a flanged connection that makes it easy to install and remove. Flanged bellows seal globe valves are suitable for applications that require frequent maintenance and inspection.
din globe valve with bellowsThis type of valve has socket-welded connection ends which are suitable for high-pressure applications.
This type of valve has a threaded connection that makes it easy to install and remove. Threaded bellows seal globe valves are commonly used for small pipeline.
This type of valve has extended bellows that provide additional protection against corrosion and allows the valve to operate at extreme temperatures and pressures.
api globe valve with bellowsThe Y-Type Bellows Seal Globe Valve is an exceptionally secure and reliable component, featuring a double sealing structure of bellows and packing. This ensures complete protection from any potential leakage at the stem, making it ideal for use in pipelines carrying dangerous, flammable, explosive, toxic or valuable substances. Additionally, its construction ensures tight seals are maintained under high temperatures and pressures, while also minimizing any risk of leaks.
din y type globe valve with bellowsTHINKTANK is a reliable globe valve manufacturer that has been producing high-quality industrial valves for over three decades. Our valves are made from high-quality materials and are designed to meet the specific needs of each application, just feel free to contact us for a free consultation.
A globe valve and a bellows seal globe valve both belong to the family of globe valves, which are used to control the flow of fluids through a pipeline or system. However, the primary difference between them is the presence of a bellows seal in a bellows seal globe valve. A bellows seal is a flexible metal component that provides a leak-proof seal and protects the stem from corrosion, which makes the bellows seal globe valve more suitable for applications that require high performance and reliability.
din globe valve with bellowsdin globe valveThe primary purpose of bellows in valves is to provide a flexible, leak-proof seal that protects the stem from corrosion and prevents fluid from eroding the stem. Bellows are also used to compensate for changes in temperature and pressure in the system, which allows the valve to operate smoothly and efficiently.
The primary difference between a bellows seal valve and a common valve is the presence of a bellows seal. A bellows seal valve has flexible metal bellows that provide a leak-proof seal and protect the stem from corrosion, while a normal valve does not have this feature.
A bellows seal is a flexible metal component that is used in valves to provide a leak-proof seal and protect the stem from corrosion. The bellows seal consists of metal bellows that is welded to the stem and a packing gland that secures the bellows in place.
The primary reason for using bellows in a valve is to provide a flexible, leak-proof seal that protects the stem from corrosion and prevents fluid from eroding the stem. Bellows are also used to compensate for changes in temperature and pressure in the system, which allows the valve to operate smoothly and efficiently.
Bellows work by expanding and contracting to compensate for changes in temperature and pressure in the system. When the temperature or pressure in the system changes, the bellows expand or contracts to allow the valve stem to move freely, which prevents damage to the valve and ensures smooth operation.
There are three types of valve seals: packing, mechanical, and bellows.
Packing seals use a flexible material, such as graphite, to provide a seal around the stem. Mechanical seals use a rotating component to provide a seal, while bellows seals use a flexible metal component to provide a leak-proof seal and protect the stem from corrosion.
The two basic types of valve seals are static and dynamic. Static seals provide a seal between two stationary components, while dynamic seals provide a seal between two moving components.
One of the primary disadvantages of bellows is that they can fail over time, which can lead to leakage and other issues. Bellows can also be more expensive than other types of valve seals, which can make them less suitable for certain applications.
Bellows failure can occur due to a variety of factors, such as fatigue, corrosion, or mechanical damage. When a bellows fails, it can lead to leakage, reduced valve performance, and other issues. Regular inspection and maintenance can help prevent bellows failure and ensure the continued performance of the valve.
The operational principle of a bellows seal globe valve is based on its unique design, which includes a bellows seal that protects the stem from corrosion and prevents fluid from eroding the stem. The valve consists of a valve body, a valve disc, a valve stem, a bonnet, a bellows seal, and packing.
When the valve is in the open position, the valve disc is lifted away from the valve seat, allowing media to flow through the valve. The stem and the disc move together as the stem is rotated by the actuator. When the valve is in the closed position, the valve disc is pressed against the valve seat, preventing media from flowing through the valve.
The bellows seal globe valve is widely used in industries where leak-proof and corrosion-resistant valves are required. Some common applications of the bellows seal globe valve are:
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The primary difference between a bellows seal valve and a traditional valve is the presence of a bellows seal. A bellows seal valve has flexible metal bellows that provide a leak-proof seal and protect the stem from corrosion, while a traditional valve does not have this feature.
20k 80 globe valve and check valveSelecting the right bellows seal globe valve for your application is crucial to ensure optimal performance, reliability, and safety. Here are some factors to consider when selecting the right bellows seal globe valve for your application:
Bellows seal globe valves offer several advantages in high-pressure and high-temperature applications, making them a popular choice for such applications. Here are some of the advantages of using bellows seal globe valves in high-pressure and high-temperature applications:
The frequency of bellows seal replacement in bellows seal globe valves depends on several factors, such as the type of fluid being transported, operating conditions, and the quality of the bellows seal.
In general, bellows seal replacement is typically required when there is evidence of seal failures, such as leakage or reduced performance. Regular inspection and maintenance can help detect signs of bellows seal failure and prevent unexpected downtime or safety hazards.
The recommended replacement interval for bellows seals can vary depending on the application and the manufacturer’s guidelines. However, a general rule of thumb is to replace the bellows seal every 2-3 years or when there is evidence of seal failure, such as leakage or reduced performance.
It is important to note that regular inspection and maintenance are crucial to ensuring the proper functioning of the bellows seal globe valve. This includes checking the bellows seal for signs of wear and damage, inspecting the stem and disc for proper alignment, and ensuring that the valve is properly lubricated.
By following the manufacturer’s guidelines and performing regular inspection and maintenance, you can ensure that the bellows seal globe valve operates safely and efficiently and that the bellows seal is replaced as needed to prevent leakage and other issues.
globe valve with bellowsHere is a table outlining some common issues that can arise with bellows seal globe valves and possible troubleshooting steps:
IssuePossible CausesTroubleshooting StepsLeakageDamaged or worn bellows seal, improperly installed valve, damaged valve body or disc, excessive fluid pressure or temperatureInspect bellows seal for signs of wear or damage, check valve installation for proper alignment and torque, inspect valve body and disc for signs of damage, check fluid pressure and temperature to ensure they are within valve limitsValve does not close completelyImproperly adjusted actuator, damaged valve disc or seat, obstruction in valve bodyCheck actuator settings and adjust if necessary, inspect valve disc and seat for signs of damage or wear, inspect valve body for obstructions and remove if necessaryExcessive noise or vibrationMisaligned valve components, excessive fluid pressure or flow rate, worn valve componentsInspect valve components for proper alignment, check fluid pressure and flow rate to ensure they are within valve limits, inspect valve components for signs of wear and replace as neededDifficult to operateDamaged or worn stem or packing, improper lubrication, misaligned valve componentsInspect stem and packing for signs of damage or wear, lubricate valve components according to manufacturer’s recommendations, inspect valve components for proper alignmentCorrosionExposure to corrosive fluids or environments, low-quality materialsSelect valve materials that are resistant to corrosion, ensure proper maintenance and cleaning to prevent corrosion buildupIn conclusion, the bellows seal globe valve is an essential component in many industries due to its unique design and functionality. Its ability to provide a leak-proof and corrosion-resistant seal makes it an excellent choice for applications that require high performance and reliability. We hope that this article provides you with valuable insights into the design, functionality, and applications of the bellows seal globe valve. Please do not hesitate to contact us if you have any questions or comments. THINKTANK is your reliable industrial valve partner here.
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