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During the processing of bellows joints, high formation stresses are generated, and the wave shape is created as a result of excessive elongation; therefore, stress-relief treatment is necessary for these bellows joints. To minimize the seam size, wire cutting is used for the separate processing of all parts. For wire cutting, first make marks, then perform the wire cutting, and finally assemble everything together to facilitate on-site assembly. After wire cutting of the pipe expansion joint, it should be reassembled. Gasket alignment welds should be made along one side of each of the three butt joints, with markings made, and then the joint should be separated again, followed by grinding of the weld grooves. When installing bellows expansion joints, pressure testing is required. During the hydrostatic test, it is necessary to consider whether temporary supports should be installed on the connections of the compensator to bear the weight when filling it with water. The water used for pressure testing must be clean and non-corrosive, with the chloride ion content in the water kept at no more than 25PPm. After the pressure testing is completed, the water accumulated in the bellows should be drained as soon as possible, and the inner surface of the bellows shell should be dried promptly. In the operation of pipelines equipped with corrugated expansion joints, valves should be opened and closed gradually to prevent sudden changes in temperature and pressure within the pipeline, which could cause damage to the supports or compensators. Installation of bellows expansion joints To extend the service life of bellows expansion joints, special attention should be paid to the following points during installation and use: 1. Before installation, the model, specifications, and piping configuration of the bellows expansion joint must be checked to ensure they meet the design requirements. 2. For compensators with an inner sleeve, care should be taken to ensure that the direction of the inner sleeve is consistent with the flow direction of the medium; for hinge-type compensators, the plane of rotation of the hinge should be aligned with the plane of displacement rotation. 3. For bellows expansion joints that require \"cold tightening\", the auxiliary components used for pre-deformation should be removed only after the pipeline installation is completed. 4. It is strictly prohibited to use the deformation of bellows expansion joints to adjust pipeline installation errors, as this may affect the normal functioning of the bellows expansion joints, reduce their service life, and increase the load on the piping system, equipment, and supporting components. 5. During installation, it is not allowed for welding slag to splash onto the surface of the wave shell, nor is it permitted for the wave shell to suffer any other mechanical damage. 6. After the piping system is installed, the yellow auxiliary positioning components and fasteners used for installation and transportation on the expansion joints should be removed as soon as possible. The limit devices should then be adjusted to the specified positions as per design requirements, so that the piping system has sufficient compensation capability under environmental conditions. 7. All moving components of the corrugated expansion joint must not be blocked by external elements or have their range of movement restricted; they should be able to move freely at all moving parts. 8. The insulation material in contact with the compensator bellows should be free of chlorine. 9. During the hydrostatic test, the secondary support brackets at the ends of the pipelines equipped with bellows expansion joints should be reinforced to prevent the pipelines from moving or rotating. For compensators used in gas media and their connecting pipelines, attention should be paid to whether temporary supports are needed when filling with water; the chloride content in the cleaning solution used for hydrostatic testing should not exceed 25PPM. 10. The insulation material in contact with the compensator bellows should be free of chloride ions. 11. After the hydrostatic test is completed, the water accumulated in the wave tank should be drained as soon as possible, and the inner surface of the wave tank should be dried promptly. The selection of bellows metal hoses is something that requires special attention when choosing such hoses. (1) Dimensions: The nominal diameter of the bellows metal hose, the type of connection to be used (mainly flange connection, threaded connection, quick-connect connection), the dimensions of the metal hose, and the length of the hose. (2) Pressure: Based on the actual operating pressure of the bellows-type flexible hose, the nominal diameter and pressure rating of the bellows metal connection are checked to determine whether a stainless steel mesh sleeve type of flexible hose should be used. (3) Medium: The chemical properties of the medium transported through the flexible hose determine the material of various components of the hose, based on the properties of the metal used to manufacture the bellows-type flexible hose. (4) Temperature: The operating temperature and range of the medium inside the bellows metal hose ； Ambient temperature during the operation of metal flexible connectors. At high temperatures, it is necessary to determine the pressure after temperature correction using the correction factor for the operating pressure and temperature of the metal hose at high temperatures, in order to select the appropriate pressure rating. (5) Condition: Refer to the correct methods of use and installation for metal flexible connections, as well as the ideal length of the hose for settlement compensation, based on the condition of the bellows-type metal flexible hose when in use. The length of bellows metal hoses in various motion states, as well as factors such as the minimum number of bends and the minimum bending radius of the hose, must be considered; the length of the metal flexible connection should be determined by selecting the appropriate parameters, and it must be installed correctly. Since bellows metal hoses are made of austenitic stainless steel, they possess excellent temperature resistance; their operating temperature range is quite wide, ranging from -196 to 600°C. In practical applications, the choice of material for such metal hoses should be based on the corrosivity of the fluid flowing through the pipes, with appropriate stainless steel grades being selected accordingly.