A tube extender is also known as expansion joint, expansion joint, compensator, expansion joint. Expansion in a certain range can be axial expansion, can overcome the pipe is not within an Angle of axial offset, can greatly convenient valve pipe installation and disassembly, free expansion in the pipeline allows expansion amount, once across its biggest ACTS as expansion amount limit, to ensure the safe operation of pipeline. Mainly to ensure the safe operation of pipeline, it has the following functions: compensation absorption pipe axial direction, transverse and angular heat deformation; Absorb equipment vibration and reduce the influence of equipment vibration on pipeline; Absorb the earthquake and the deformation of the pipe.