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Steel expansion bellows are also named for the expansion joints, Bellow expansion joint, bellows compensator, is a kind of flexible, thin wall, a transverse corrugated device with telescopic functions, it is made up of metal corrugated pipe and components. Bellows compensator’s working principle is mainly using their elastic scaling, to compensate the axial, angular, lateral and combined compensation due to pipes’ thermal deformation, mechanical deformation and all kinds of mechanical vibration, the role of compensation has pressure, sealing, corrosion resistance, temperature resistance, impact resistance, anti-vibration noise reduction function, it could reduce the pipe deformation and prolong the service life of pipelines.

Steel expansion bellows classification:

1)  According to whether can absorb piping within the medium pressure generated by the thrust (blind plate force), steel expansion bellows can be divided into no constraint expansion bellows and constraint expansion bellows;

2)    According to the displacement type of expansion bellows, it can be divided into axial type, horizontal type expansion bellows, and angular type expansion bellows and pressure balance type expansion bellows.

How to choose steel expansion bellows

Expansion bellows’ scale effect depends on corrugated pipes. Expansion bellows function and strength design is mainly to the design of corrugated pipe. Different design and combination of bellows can make bellows stretching, compression or bending, thus forming the axial, lateral and angular three basic forms of corrugated compensator. So the design of the corrugated tube is the key to expansion bellows is designed.

The design of bellows are very complex, it needs to calculate and check the following parameters: pressure capacity, displacement caused by stress, the fatigue life, stiffness and stability.

Expansion bellows stress is caused by internal pressure and displacement, stress caused by displacement is usually greater than the internal pressure caused by stress, it is along the meridian to the direction of the corrugated pipe (warp), general is higher than the yield strength of corrugated pipe materials.