Bellows is a mechanical device that produces pressurized air which consists of chambers that can be expanded in controlled quantity and controlled location to draw in air through a valve and contract it to eliminate it through a tube.

In ancient times, bellows were used to provide more air to fire in order to keep it burning and used in household field such as cooking (both welded and convoluted). However, today bellows are used extensively for number industrial application.

Welded bellows are generally made of any metal or alloy which can be welded. They can be fabricated in various sizes and shapes accordingly to obtain a higher performance option than formed bellows. Formed or convoluted bellows on the other hand are used in larger application such as large piping system or HVCA (heating, ventilation, and air conditioning).

Metal bellows are used in various segment which includes medical application, aerospace and space application to collect waste water and many more. Under hydraulic or pneumatic pressure, metal bellows create information needed for the instrumentation world. Gauge, barometric and different pressures and temperature can all be compensated for using bellow technology. Moreover bellows create a connection in the system for instrumentation such as actuators and encoder.

Valves, valves actuator and valve assemblies rely on bellow technology to seal and provide feedback. From sub-sea and down-hole tool to aerospace component, bellows are used for critical application. In piping system, a degree of flexibility in the design is needed. Creating pipe loops or direction change are costlier methods to use expansion joints because of space problems, pressure drop, piping material etc. This can be eliminated by use of bellow expansion joint.

Rubber bellows are primarily used to absorb noise and thermal movements along with removal of vibration between equipment such as cooling water pumps, diesel engines, condensers, chillers and their mating pipe work. Rubber bellows can be used just like a metal expansion joint to compensate for axial, lateral or angular movements.

In semiconductor and ultra-high vacuum (UHV) manufacturing, edge welded bellows are used as flexible penetrations into process chambers. Mechanical seals are mounted on pump shaft. Bellows are used to close the inside of a pump from outside to prevent leakage.

Apart from industrial and mechanical applications, bellows are also used in anesthesia machines, articulated buses and trams to cover the joints where vehicle bends, in creating musical instruments, cuckoo clocks and many more.