The compensator is also called expansion joints, or expansion joints. By the composition of the main body of the bellows (an elastic element) and end pipe, bracket, flange, pipe and other accessories. Belong to a kind of compensation element. The main work bellows effective stretching deformation, absorption pipeline, pipe and containers by thermal expansion and contraction and other reasons arising from the changes in size, or compensating pipe, catheter, containers, etc. the axial, transverse and angular displacement. Can also be used for noise reduction and vibration. Widely used in modern industry. Heating, to prevent the heating pipe temperature, due to thermal expansion and the temperature stress caused by pipeline deformation or damage, need compensator is arranged on a pipeline, to compensate for the pipeline thermal elongation of, thus reducing pipe wall should force and role in the valve or scaffold structure force.