The bellow expansion joint needs to be pre-stretched or pre-compressed when installed. The purpose of pre-tension or pre-compression is to ensure that the bellow expansion joint can be evenly stressed after installation, increasing its service life and fatigue times. The amount of pre-stretching is usually half of the compensation amount, and the circumferential surface of each wave node should be evenly stressed during the stretching or compression process, and it should be installed and fixed after stretching or compressing to the required quantity.

      In addition, the installation direction of the bellow expansion joint also needs to pay attention to the following points:
      1. Installation direction: The installation direction of the bellow expansion joint should be consistent with the flow direction of the medium, especially the compensator with an inner sleeve to ensure that the medium can flow smoothly.
      2. Concentric requirements: During installation, it should be ensured that the bellow expansion joint and the pipeline remain concentric and should not be deflected, so as to avoid the circumferential torsion of the expansion joint caused by installation.
      3. Bracket installation: Fixed brackets should be installed at both ends or above the bellow expansion joint to fix and support the bellow expansion joint to prevent its displacement and shaking.
      4. Protection measures: During the installation process, welding slag should be avoided from splashing on the surface of the bellows, temporary supports should not be welded on the bellows, and the hoisting rigging should not be directly tied to the bellows to avoid mechanical damage to the bellows.
      5. Connection: The connection of the bellow expansion joint should meet the relevant pipeline connection standards and requirements, and the commonly used connection methods include flange connection, welded connection, etc.