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A metal bellows expansion joint is considered to be an extension or compression of a piping system in its longitudinal axis, which means that the total length of the expansion joint is extended or compressed during the absorption of movement. Axial expansion joints designed to absorb large movements can contain one, two or more bellows in a single unit, or larger movements can be achieved by pretensioning or installing multiple expansion joints on a pipe section.
Choosing the correct material for your metal bellows is critical. Stainless steel bellows are designed to withstand high pressures, high temperatures or critical media.
Stainless steel bellows are widely used where temperature, pressure or media prevent the use of rubber bellows. They are made of thin-walled tubes with the number of convolutions determining the available movement. For bellows units, only a relatively small amount of convolution can be safely designed before the unit becomes unstable under pressure. For larger motion requirements, additional bellows must be installed or an alternative system design must be used. Since each expansion problem usually has specific design criteria, each bellows is designed and manufactured to meet customer requirements including length, pressure, end termination and movement requirements.
Axial Bellows
Axial bellows are designed to absorb the thermal expansion of straight pipe sections operating below 10 bar. Each unit must be installed between two anchor points with adequate guiding over the entire length of the pipe.
Double-layer bellows
The double system bellows is designed to absorb thermal expansion in the transverse plane and is usually placed at an angle of 90 degrees to the main pipe. Greater movement capacity can be obtained from the two transverse planes of the system. These units can also accommodate some axial movement.
Double-Hinged Bellows
Double-hinged bellows are positioned in the same way as double-system bellows and can also absorb larger movements. Unlike double-series bellows, lateral movements can be made in only one plane due to the hinge bracket. These systems are very suitable for high pressure systems, or where the forces on the anchor point cannot be controlled.
Single hinged Bellows
Single hinged bellows are used in two or three pin systems that need to withstand large amounts of expansion. Again, these units are ideal for high pressure applications and work in a similar manner to double-hinged bellows.
End Fittings
Each bellows is offered with a range of end connections including fixed or swivel flanges, stubs, BSP male and female threads, and copper stubs.
▸Precision bellows for volume compensators
▸Pressure and temperature sensors; height measurement in aerospace
▸Flexible connectors (expansion joints); absorption of vibration and thermal expansion
▸Metal bellows couplings; torsional (rotational) moments can be compensated
▸Bellows valves (gate, safety or check valves); hermetic stem seals while compensating for the relative motion between the valve plate and the housing caused by the opening and closing of the valve system
Expansion joints have rectangle-shaped areas as well as waveform with similar shape. A solitary expansion joint in the pipeline bears two-dimensional displacement. The pipe comprising 2 expansion joints can bear three-dimensional displacement. Metal expansion joints could be classified right into full-height expansion joints and also half-height expansion joints.
1. After the user pick the proper expansion joint based on the thermal displacement of the piping system, they have to offer information regarding the tool from the pipe, style stress of the duct, the greatest temperature throughout procedure, the general dimension of sections of the duct, the chosen waveform and the quantity of the waveform to be able to make and also make structure of expansion joints.
2. The maximum allowed expansion of each waveform
Full-height type: △ α = ± 24 mm Half-height: △ α = ± 12 mm.
3. In order to decrease the variety of the waveform, we need to consider the cold-drawn process for expansion joints.
4. The ash board: For pipelines with much less dirt, the ash board doesn%u2019t demand to be made use of for flue pipes with much dirt, the ash board should be embraced.
5. Expansion joints are suitable for pipes whose cross-sectional locations are less than 4.6 square meters and also one side of the overall measurement of the air and also flue gas duct which is less than 1.5 m but higher than 0.6 mm. Standard full-height expansion joints can be put on all air as well as flue gas ducts.
