The Overview of the main application of metal bellows:

The characteristic of metal bellows is, it can produce displacement under the action of pressure, axial force, lateral force or bending moment, and has pressure resistance, vacuum sealing, corrosion resistance, temperature stability and long-term service life. Therefore, it is widely used in many industrial fields. The main application is as follows:

  • 1,As Elastic sensitive components applied for instruments:
    • Metal bellows used as elastic sensitive elements basically change pressure to displacement output or pressure to centralized output. The bellows that change the pressure to a concentrated force output have little or no deformation. So the pressure generated on the ripple is less than the stress on the bellows ripple with output displacement, and the effect of the elastic after-effect, hysteresis can be said to be absent.  Therefore, the reliability and accuracy of the instrumentation of force-balanced bellows as elastic sensitive elements can be very high. This is the reason why, in measuring instruments, more force is used to balance the bellows as an elastic sensitive element. The pressure into displacement output of the bellows in the corrugation will produce greater pressure, the design should be paid attention to, at the same time, elastic after-effect, hysteresis on the elasticity of the bellows has a certain effect
    • The bellows used as the elastic sensitive element in the instrument, the rigidity of the bellows should be minimized when designing
    • According to the change of the volume of the inner cavity (or external) during the displacement of the metal bellows can be used for temperature control and temperature measurement
  • 2,As Vacuum seal Applied for vacuum switch
    • The vacuum switch is switchgear that can be used to disconnect the electrical flow in vacuum, its main contact is located in the vacuum interrupter chamber, metal bellows is the key element in the vacuum interrupter chamber, only after using metal bellows can it be possible to make the moving contact move by mechanical force from the outside of the vacuum interrupter chamber, but also can keep the vacuum interrupter chamber shell completely sealed. Each time the vacuum switch is on and off, the metal bellows will make a large displacement, large and frequent axial displacement is easy to damage the metal bellows due to lifetime. The metal bellows is an important part of the vacuum interrupter housing, if it is damaged, the life of the vacuum interrupter will be terminated due to air leakage. The other parts of the vacuum interrupter are not easily damaged in normal operation, so the lifetime of the metal bellows also determines the mechanical life of the vacuum interrupter. In addition, the contact opening distance of the vacuum switch is equal to the actual axial displacement of the metal bellows. Therefore, the permissible axial displacement of the metal bellows also determines the maximum contact opening distance that can be obtained.
    • The lifetime of the metal bellows is related to its structure and materials used, but also has a lot to do with the conditions of use. The working stroke of the metal bellows used in the vacuum switch has a significant impact on its lifetime. For the same metal bellows, the same vacuum switch, a longer lifetime can only be achieved by reducing the working stroke of the metal bellows or by triggering the opening distance. On the contrary, if the working stroke or contact opening distance of the metal bellows is increased, the lifetime of the metal bellows will be greatly reduced. Therefore, the main properties of metal bellows for vacuum switching are axial displacement and vacuum sealing. Vacuum switch has two working states, on or off, in the turn-on, metal bellows need to stretch deformation, break,  metal bellows compression deformation, in order to ensure the lifetime of the vacuum switch, metal bellows stretch and compression of the displacement must be designed to be reasonable.
    • Both hydraulically formed metal bellows and welded metal bellows can meet the requirements of ordinary vacuum switches, considering the cost of manufacturing, general the hydraulically formed bellows will be used for vacuum switches. Only when there require an exceptionally long service life with a large travel of the cargo contacts. , then choose welded bellows for vacuum switches. The bellows material is generally stainless steel 1Cr18Ni9Ti,00Cr17Ni14Mo2 and 0Cr18Ni9. The structure of the vacuum extinguishing neglect is shown as bellow.shown in the figure.
  • 3,Used as a valve isolation element
    • Metal bellows valves, whether they are shut-off valves, throttle regulators, or valves such as pressure reducing valves, the metal bellows are sealed isolation elements that act as packing-free stems. During valve operation, the bellows undergo axial displacement and reset along with the stem, while it is subjected to fluid pressure and is absolutely sealed.  Metal bellows axial displacement and the valve diameter, for the plane seal shut-off valve, the working stroke of the metal bellows is generally 1/4 of the diameter. Metal bellows axial displacement stroke should be moved by the mechanical limit of the valve stem to limit the range. Metal bellows are not allowed to be metal bellows corrugated against the plastic deformation, but also to prevent the metal bellows received distortion deformation, in the valve, the main performance of the metal bellows is pressure resistance, working displacement and fatigue life. The effective forms of metal bellowing are mainly fatigue rupture, stress corrosion damage and bellows instability. The factors affecting the service life of metal bellows are mainly the working pressure, working displacement, working temperature, fluid medium, wave structure, raw material quality, pressure shock, vibration, connecting parts structure and assembly quality. In metal bellows valves, metal bellows are the most easily damaged parts, so the design and selection of metal bellows are very important, if the design is not reasonable, often cause premature failure of the valve. Bellows valves offer greater reliability and longevity compared to packing-sealed valves. It has been widely used in the nuclear industry, petroleum, chemical, pharmaceutical, aerospace and other industrial fields.  The flanged metal bellows shutoff valve is shown as below.
  • 4,Used for metal bellows expansion joints
    • Metal corrugated expansion joints are widely used in a variety of piping systems to compensate for axial, lateral and angular displacement due to temperature and pressure fluctuations. The core part of the metal bellows expansion joint is the metal bellows, through the deformability and pressure sealing of the metal bellows for axial, lateral and angular displacement, and to withstand the fluid pressure of the system, other parts are structural parts, to play the role of guidance, support, link, backflow and so on. According to the design and use requirements, the metal bellows and related structural parts are welded into axial, transverse and angularly impassable types of metal bellows expansion joints according to the required structure.
  • 5,Used for metal hose as Flexible connector
    • As the flexible characters, the metal hose is used to compensate for position deviations in the piping system caused by installation and to meet the requirements of the working end displacement in all directions and to withstand the fluid pressure of the system. The core part of a metal hose is a bellows, the ratio of length to inner diameter is generally greater than 3. The waveform is divided into a ring and a spiral, the bending stiffness of the ring is less than that of the spiral. To increase the pressure-bearing capacity of the metal hose, in many cases the outside of the wave tube is armoured with wire or woven metal mesh.
  • 6,Used for bellows heat exchanger as heat exchange element
    • The metal bellow heat exchanger is an efficient, reinforced heat exchanger that is the product of a multidisciplinary combination of metal forming, mechanics and heat transfer. Metal bellows as heat transfer tube bundle mainly play the role of strengthening heat transfer, but also plays the role of thermal compensation and anti-vibration. The ageing forms of metal bellows are mainly fatigue fracture, stress corrosion fracture and corrosion fracture. In the metal bellows heat exchanger, the main properties of metal bellows are heat transfer efficiency, fatigue life, pressure resistance, temperature resistance, corrosion resistance, vibration resistance and thermal compensation. The heat transfer efficiency is mainly related to the waveform, which affects the process of forming the metal bellows.

Metal bellows are also used in other products and markets, including medical applications such as implantable drug pumps, industrial actuators, aerospace applications such as height sensors and fluid management devices (accumulators, surge amplifiers, volume compensators and fluid storage). Metal bellows can also be used as experimental research materials in physics institutes, universities, etc. For more, you can contact us as below:

What is Metal Bellows?

The Structure and kinds of metal bellows