Expansion joints (also known as bellows compensators or expansion joints) play a crucial role in piping systems. Here are the main roles of expansion joints:

1. Compensation for axial, transverse and angular thermal deformation of absorption pipe:
   The expansion joint is able to compensate for the thermal deformation of the pipe due to temperature changes. Whether it is axial, transverse or angular thermal deformation, the expansion joint can absorb these changes through its own expansion and contraction deformation, thus ensuring the stability and safety of the pipe system.

2. The expansion and contraction amount of bellows expansion joint is convenient to adjust:
   The amount of expansion and contraction of the expansion joint can be adjusted as needed. This makes it able to adapt to the requirements of different pipeline systems for compensation amount, thus ensuring the normal operation of the pipeline system under various working conditions.

3. Convenient installation and disassembly of valve pipeline:
   In pipeline systems, the installation and disassembly of valves and equipment often requires a certain amount of space. The expansion joint can absorb the expansion and contraction deformation of the pipe, thus providing enough space for the installation and disassembly of valves and equipment, making the operation more convenient.

4. Absorbing the deformation of pipelines caused by earthquakes and ground subsidence:
   During natural disasters such as earthquakes or ground subsidences, pipeline systems tend to be severely impacted and deformed. The expansion joint can absorb these amounts of deformation, thus mitigating the damage to the pipeline system and ensuring the safe and stable operation of the pipeline system.

5. Absorb equipment vibration and reduce the impact of equipment vibration on pipelines:
   In industrial production, many devices generate vibrations during operation. These vibrations can cause some impact and damage to the plumbing system. The expansion joint can absorb the vibration of the equipment and reduce the impact of vibration on the pipeline, thus prolonging the service life of the pipeline.

6. Easy Plumbing Repair:
   When the pipeline system fails and needs to be repaired, the presence of expansion joints can provide enough space for maintenance personnel to make the maintenance work more convenient and efficient.

In summary, expansion joints play a crucial role in piping systems. It can not only compensate the thermal deformation and vibration deformation of the pipeline, but also provide enough space for the installation and disassembly of valves and equipment, and absorb the influence of natural disasters and equipment vibration on the pipeline. Together, these actions ensure the safe and stable operation of the pipeline system.