A bellows seal globe valve is a specially designed valve that is highly suitable for industries dealing with hazardous substances. The valve’s unique design ensures that even the smallest leakages, which can be extremely critical in certain industries, are prevented. This is particularly important in industries such as the chemical and nuclear industry, where there is a high risk of leakage, explosion, and health hazards due to the flow of flammable, hazardous, extremely poisonous, and toxic media through the pipelines. The bellows seal globe valve, therefore, meets specific stringent leakage and sealing requirements that are essential in such industries.
You will get efficient and thoughtful service from Afbv Valve.
The Comprehensive Guide to Bellow Seal Globe Valves 1Bellows seal globe valves work by using a compact structure that includes bellows for sealing the valve stem components. The bellows valve has a bellow inside, and the lower end of the stainless-steel bellows is welded to the stem to prevent the system fluid from eroding the stem. The other end is positioned between the body of the valve and the cover of the valve to create a permanent seal. This double seal configuration eliminates leakage. Even if the bellows collapse, the stem packaging will prevent further leakage. The bellows are welded to the valve stem to ensure stable operating efficiency and prevent the vibration of the valve stem induced by the movement of the valve insert.
The Comprehensive Guide to Bellow Seal Globe Valves 2The key components of a bellows seal globe valve include the metal bellows, bonnet, the lower end and stem assembly, the upper end and connecting plate, and the sealing surface of the valve disc.
The metal bellows are the main feature of a bellows seal globe valve. They are made by rolling a flat sheet into a tube and then mechanically forming it into a bellow with rounded and widely spaced folds. Inconel is a common material used for making bellows due to its high resistance to corrosion and high temperatures. Cryogenic valves are also commonly made with metal bellows for their ability to withstand extreme temperatures.
The lower end and the stem assembly are welded together, while the upper end is welded on the connecting plate using socket weld. This creates a metal shield between the fluid medium and the environment, ensuring zero leakage from the valve stem. The stem seals are an important component of the bellows seal globe valve, ensuring a tight seal and preventing leaks.
The sealing surface of the valve disc and the valve structure is precisely ground to confirm that it has passed a pressure rating test and that any possibility of leakage is eliminated. Graphite packing is used to ensure a tight seal and prevent any leaks from occurring.
Bellows seal globe valves are a crucial component in a wide array of industries due to their exceptional sealing capabilities and robust design. The primary industries that utilize these valves are those where the prevention of leakage is of utmost importance, particularly when dealing with hazardous or toxic substances. These valves can be integrated with an API (Application Programming Interface) to provide real-time monitoring and control, making them an even more valuable asset in industries where safety and efficiency are top priorities.Petrochemical Industry: One of the key sectors that heavily rely on bellows seal globe valves is the petrochemical industry. These valves are used in various processes where they control the flow of flammable and potentially harmful substances. Their superior sealing performance ensures that there are no leakages that could lead to accidents or environmental contamination.Nuclear Industry: The nuclear industry is another sector where bellows seal globe valves, classified as ASME Class, are extensively used. In nuclear power plants, these valves play a crucial role in controlling the flow of radioactive substances. The double sealing design of these valves ensures that there is no leakage of radioactive material, thereby ensuring the safety of the plant and its surroundings.
The Comprehensive Guide to Bellow Seal Globe Valves 4Chemical Industry: Bellows seal globe valves are also widely used in the chemical industry. They are used to control the flow of various chemicals in the production processes. The valves’ ability to withstand corrosive substances and high temperatures makes them an ideal choice for this industry.Electronics Industry: Other industries that use bellows seal globe valves include the electronics industry, where they are used in the production of semiconductors and other electronic components. They are also used in various plants such as power plants, water treatment plants, and manufacturing plants where they control the flow of gases and liquids. The vacuum industry also uses these valves due to their ability to maintain a high level of sealing under low-pressure conditions.
Bellows seal globe valves come in various types, each designed to meet specific application requirements. Here are some common types:
In conclusion, bellows seal globe valves are an essential component in many industries due to their superior sealing capabilities and robust design. They offer numerous advantages, including enhanced safety, environmental protection, and energy conservation. However, it’s important to select the right bellows and take necessary precautions to ensure safe and efficient operation.
When it comes to bellows seal globe valves, Dombor is a trusted name in the industry. With a commitment to quality and innovation, Dombor offers a wide range of bellows seal globe valves designed to meet the specific needs of various industries. Whether you need a welded ends bellow seal globe valve for high-pressure applications or a flanged bellow seal globe valve for easy installation and maintenance, Dombor has you covered. With Dombor, you can be assured of superior performance, durability, and reliability. Choose Dombor for all your bellows seal globe valve needs.
Leakage at various points in pipelines found in chemical plants creates emissions. All such leakage points can be detected using various methods and instruments and should be noted by the plant engineer. Critical leakage points include flanged gasket joints and the valve / pump gland packing, etc. Today the chemical process industry is gearing itself towards safer technology for better environmental protection and it has become every process engineer's responsibility to design plants that limit damage to the environment through the prevention of leakage of any toxic chemicals.
Leakage from the valve gland or stuffing box is normally a concern for the maintenance or plant engineer. This leakage means..
a) Loss of material b) Pollution to the atmosphere c) Dangerous for plant employees.
If you are looking for more details, kindly visit Forged Steel Bellow Seal Gate Valve.
For example, take the case of a steam leakage through the valve gland. At 150 PSI, a clearance of just 0.001" through the gland will mean a leak at the rate of 25 lb/hour. This equates to a loss of USD 1.2 per eight hour shift, or USD 1,100 per year. Similarly, a tiny drop of 0.4 mm diameter per second results in a waste of about 200 litres per year of costly oil or solvent. This leakage can be reduced considerably by using the bellow seal valve. This article will now consider the construction and operation of the bellow seal.
The bellow cartridge is welded to both the valve bonnet and the valve stem. The bellow cartridge has a number of convolutions and these convolutions become compressed or expanded depending upon the movement of valve stem. (Scientifically speaking the bellow gets compressed when the valve is in the open position and expanded when the valve is in the closed condition). It is important to properly install the valve bodies. The bellow can be sealed to the valves in two different ways. Firstly, the bellow can be welded to the Valve stem at the top and the valve body on the bottom. In this case the process fluid is contained inside the bellow or in second method the bellow is welded to the valve stem at the bottom and the body on the top. In this case the process fluid is contained in the annular region between the valve bonnet and bellow (from the outside).
The bellow is a critical component and forms the heart of the bellow seal valves. To avoid any twisting of the bellow the valve must have a stem with linear movement only. This can be achieved using a so-called sleeve-nut at the Yoke portion of the valve bonnet. A handwheel is fitted onto the sleeve-nut which effectively transfers a rotary motion of the handwheel into a linear motion in the valve stem.
There are two main types of bellow.. the Forged Bellow and the Welded Bellow. Formed-type bellows are made from rolling a flat sheet (thin wall foil) into a tube which is then longitudinally fusion welded. This tube is subsequently mechanically or hydrostatically formed into a bellow with rounded and widely spaced folds. The welded leaf type bellow is made by welding washer-like plates of thin metal together at both the inner and outer circumference of the washers - like plates. A welded leaf bellow has more folds per unit length as compared to forged bellows. Thus, for the same stroke length, forged bellows are two to three times longer than their welded leaf counterparts.
Reportedly, mechanically forged bellows fail at random spots, while the welded leaf usually fails at or near a weld. To ensure full penetration of bellow ends and end coller welding it is advisable to fabricate using micro plasma welding.
The multi-ply bellow design is preferred for handling higher pressure fluids (generally two or three plies of the metal wall). A two ply bellow can increase its pressure rating by 80% to 100% as compared to a single ply bellow of the same thickness. Alternatively, if a single ply bellow of a thickness equivalent to a pressure rating of a two ply bellow is used, the stroke length is reduced. Thus, a multi-ply bellow design offers a distinct advantage over a single ply bellow. It is clear that the bellow is subject to metal fatigue and this fatigue can induce weld failure. The bellow fatigue life is affected by the material of construction, fabrication technique, stroke length and stroke frequency, in addition to the usual parameters such as fluid temperature and pressure.
The most popular stainless steel bellow material is AISI 316Ti which contain Titanium to withstand high temperatures. Alternatively, Inconel 600 or Inconel 625 improve fatigue strength and corrosion resistance as compared with stainless steel bellows. Similarly, Hastalloy C-276 offers greater corrosion resistance and fatigue strength than Inconel 625. Fatigue resistance can be improved by using a multiply bellows system and reducing the stroke length; this can significantly increase the bellow service life.
The most common valve types to be fitted with bellow seals are the gate and globe designs (see Figure 1).These are very suited for use with bellows due to their internal construction and axial movement of the valve stem.
Based on available information, it seems that current bellow seal valves range in size from 3 mm NB to 650 mm NB. Pressure ratings are available in from ANSI 150# to 2500#. Material options for the valves include carbon steel, stainless steel and exotic alloys.
Applications
Heat Transfer media.. hot oil is commonly used in industries such as synthetic fibres / POY (Partially Oriented Yarn). However, there is always a risk of fire due to hot oil spillage on highly inflammable chemicals. Here, bellow seal valves can stop the leakage.
Vacuum / ultra high vacuum.. some applications require a vacuum pump to continually extract air from a pipeline. Any conventional valves installed on the pipeline can allow external air to enter the pipeline thorough the valve stuffing box. Hence the bellow seal valve is the only solution to prevent air from passing through the stuffing box.
Highly hazardous fluids.. for media such as chlorine (see Figure 2), hydrogen, ammonia and phosgene, the bellow seal valve is an ideal design as leakage through the gland is totally eliminated.
Nuclear plant, heavy water plant.. in instances where radiation leakage is to be prevented at all times, the bellow seal valve is the ultimate choice.
Costly fluids.. in some applications leaks need to be avoided simply because of the high cost of the fluid. Here, an economic assessment often favours the use of bellow seal valves.
Environmental standards.. around the world, standards regarding emissions and the environment are getting more stringent day by day. It can therefore be difficult for companies to expand within existing premises. With the use of bellow seal valves, expansion without additional environmental
damage is possible.
Want more information on DIN Bellows Seal Gate Valve? Feel free to contact us.