Natural compensation is the most economical method in pipeline compensation design. Natural compensation is flexible methods by the use of the natural bending of the pipeline to compensate the thermal displacement, which is limited, when the natural compensation can not meet the requirements, metal bellows expansion joints and other compensation devices can be used. A load of the pipeline is mainly external load (pipeline and liquid medium weight, internal pressure, wind and earthquake load, etc.) and displacement load, the expansion joint can eliminate the external load on equipment or pipeline, it can divide the complicated piping system into single and independent section to ensure the best use of expansion joint effect. The pipeline expansion joint can compensate the axial, transverse and angular thermal deformation, absorb the vibration of the equipment and deformation of the pipeline caused by earthquake and subsidence, reduce the impact of the vibration of the equipment on the pipeline. The pipe expansion joint is used in cold and hot pipeline systems, iron and steelworks, thermal power plants, smoke exhaust desulfurization, dust removal equipment, air heating, flow aid blast and another equipment outlet.
The bellows compensator is a compensating element that makes use of the effective expansion deformation of bellows to absorb the size changes of pipelines, ducts or vessels caused by thermal expansion and cold contraction.
According to the displacement form classification, the bellows compensator can be divided into axial, transverse, angular and pressure balance bellows expansion joints. According to the pipeline whether absorbing the pressure thrust (blind plate force) in the pipeline, it can be divided into unconstrained corrugated expansion joint and constrained bellows expansion joints. According to the bellow structure parameters, it can be divided into U shape, Ω shape, S shape and V shape bellow expansion joint (corrugated pipe), among which U shape structure is the most used.
Bellow compensator is generally used for where nominal pressure is less 1.0Mpa, nominal diameter is more than150mm, can also be used for atmospheric pressure and low pressure of large diameter pipeline. The application in the boiler or smoke pipe can reach DN4000mm. But the bellow compensator has the advantage of low pressure, small compensation capacity, pipe wall that can not bear torsion and vibration, poor safety; Axial bellow compensator produces large thrust on the fixed bracket, and the cost is high. During installation, the data recommended by the manufacturer should be followed to avoid affecting the normal function of the ripple compensator. Enough space should be left around the expansion joint to ensure a free move.
Small size, lightweight, easy to install and disassemble.
Long service life. The inner guide tube of the bellows reduces the flow resistance of the fluid and avoids the erosion of the wall surface of the bellows by the medium flow, which extends the service life of bellows, especially for stainless steel bellows.
Good sealing performance. Compared with the casing compensator, the bellows compensator does not require maintenance and has higher pressure bearing capacity and operating temperature.
Bellow compensator is one of the most commonly used expansion joints. But the bellows compensator still has some defects that cannot be ignored, such as small compensation capacity and high price.
The rotary compensator is a new type of compensator for thermal expansion of the pipeline, which is mainly composed of the integral sealing seat, sealing gland, reducer, antifriction centering bearing, sealing material, rotating cylinder and other components. More than two relatively rotating absorption pipe thermal displacement is required to reduce the stress of the pipe. The rotating compensator is generally installed in a group of 200 ~ 500m (which can be determined according to the natural terrain). According to the direction of the pipeline, the distance between the fixed supports increases. In order to reduce the friction resistance of the pipe section, rolling support can be installed on the sliding support.
Reasonable structure and high safety. Double seal form, one side for the end seal, one side for the ring seal;
A large amount of compensation. The compensation amount can reach 1800 mm (for other compensators, such as bellows compensator, the maximum compensation amount is 300 ~ 400 mm). For pipelines above DN 200, the unilateral compensation amount can reach 130 ~ 200 m. For pipelines ≤DN 200, the unilateral compensation amount can reach 100 ~ 130 m, which can be used for long-distance steam pipeline compensation.
Long life and economy: life can reach more than 20 years. The rotary compensator has a long compensation distance. Compared with natural compensation and sleeve compensation, the use of the elbow is reduced. It can be used as one of the main compensation methods for long-distance heat transmission network
Convenient installation and disassembly: According to the direction and terrain of the pipeline, you can choose an appropriate type of rotary compensator compensation, without cold pull, pre-tightening and other construction, which should consider the stress of bellows compensator, sleeve compensator, blind plate force, etc.
The square compensator is also called square expansion or expansion bending, it uses the elastic deformation of seamless steel tube bending to absorb the thermal expansion of the pipeline. In order to avoid the pressure of the heat pipe is too long or the foundation settlement on the pipe, it is necessary to install a square compensator to reduce the stretching of the pipe caused by "heat expansion and cold contraction". When installing the square compensator, the outer pipe must be pulled a certain length in advance before installation in order to reduce the deformation elastic force and improve the compensation ability.
Easy to manufacture and install. Compared with the sleeve and the bellow compensator, the axial thrust on the fixed bracket is smaller and the thermal compensation is larger. It is suitable for various pressure and temperature conditions.
Maintenance-free, safe, no need to set up inspection Wells.