First.
The compensator is also called expansion joint. In the piping system, the bellows compensator can absorb the thermal expansion caused by temperature difference while bearing the pressure of the system. The compensator is composed of corrugated elements and nozzle, cylinder, outer guard tube and end plate. Successful applications have been obtained in metallurgical, petroleum, chemical, electric, heating and refrigeration systems, as well as low temperature equipment, which can be absorbed to the axial, transverse and angular displacement. The typical working conditions are: pressure from vacuum to 6.4MPa, and temperature from -200 to 1350 C.
Unlike ordinary pipe elements, the bellows are made of quite thin materials to make it flexible enough to absorb the mechanical displacement and thermal displacement expected in use, and also play a role in vibration and noise reduction. In the design, manufacture, transportation, installation, testing and other links, we must pay attention to the uniqueness of this product.
Custom made stainless steel corrugated expansion compensator, high temperature corrugated compensator
Two. Bellows design and main performance parameters
Bellows are the core components of bellows compensator, and are the key functional components of bellows. The performance of bellows compensator mainly depends on bellows element.
Classification of wave structure of 2.1 bellows
Corrugated tubes are divided into U shape, Omega shape, S shape and C shape. The different waveforms have different performance characteristics.
Characteristics of 2.1.1 U shaped bellows
U bellows is the most widely used waveform at present. Its characteristics are: under the same wall thickness condition, the bearing capacity is high, the compensation ability is large, the stress distribution is uniform, the fatigue life is high, and the comprehensive performance is good. The performance of U bellows is mainly determined by wall thickness, wave height, wave spacing, layer number and so on.
Characteristics of 2.1.2 Omega bellows
The shape of the Omega bellows is characterized by high resistance to the section, but low compensation capability and low rigidity. The utility model is suitable for occasions with high pressure, small displacement and small deflection, and the manufacturing process is complex.
Characteristics of 2.1.3 C shaped bellows
The C shape bellows are characterized by high bearing capacity, low compensation capability, high rigidity and simple manufacturing process. In general, it is not used.
Characteristics of 2.1.4 S shaped bellows
S shaped bellows are characterized by high pressure bearing capacity, but the compensation ability is slightly lower, the process is poor, and the manufacturing is more complex, but it is not easy to produce stress concentration, the stress state of the bellows is better, and the stiffness is lower than the U shape. S type bellows can be used when both high pressure and large displacement are required.
At present, bellows compensators are mostly using U bellows. The U shaped bellows has good manufacturability, easy processing, good pressure resistance and compensation capability. No enhancement U bellows are generally suitable for occasions with pressure less than 2.5MPa.
2.2 U shaped bellows are classified according to the number of layers
It can be divided into single layer bellows and multi-layer bellows.
Single layer bellows consist of a tube wall, easy to fabricate, but the compensation capability is general. The multilayer bellows is made up of multi-layer tube walls, which are like many thin leaf springs, so the stiffness is small. Compared with single-layer bellows, the multilayer bellows are easy to deform and have great compensation capability under the same wall thickness and wave shape. The stress generated by the deformation is small and the fatigue life is high. Therefore, it can meet the requirements of large compensation and high pressure impact (single layer bellows require tube wall thin, ripple depth, multi-layer bellows requiring pipe wall thickness, ripple shallow) under certain working conditions, that is, under certain pressure, compensation and fatigue life, multi layer bellows are smaller and shorter than single layer bellows. The multi-layer corrugated expansion joint is compact in structure, saving material and easy to manufacture. Because of the small wave height, it is easy to install the outer sleeve and easy to install and support. When corrugated expansion joints are used for corrosive environments, multilayer bellows are made of corrosion resistant materials both inside and outside, thus saving valuable metals. Sometimes, for the sake of antisepsis, the inner and outer layers can be made of materials with larger thickness. In addition, if the inner layer of the inner wall appears to be cracked for one reason, such as corrosion, defect, fatigue, installation and so on, although the inner layer has leaked, the other layers can still be sealed, so the multi-layer corrugated expansion joints are not easy to burst and prolong the maintenance period.
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