4、 Conclusion
1) There is stress concentration in the assembly gap on the root structure of the welded joint, so it is necessary to conduct CTOD test to investigate the fracture toughness of the joint.
2) The test results show that the minimum CTOD value of the weld and heat affected zone is 0.196mm, which is greater than the requirements of 0.125mm in Appendix A of API 1104 and 0.15mm in DNV-OS-C401. The weld itself meets the requirements of Class 1 pressure vessel in JB4730-94 through NDT, so it can be recognized that the welded joint has sufficient fracture toughness value, which is sufficient as the basis for post weld heat treatment free.

Compensators can be divided into unconstrained bellows compensator and constrained compensator according to whether they can absorb the pressure thrust (blind plate force) generated by the medium pressure in the pipeline; According to the displacement type of bellows, it can be divided into axial type compensator, transverse type compensator, angular type compensator and pressure balanced bellows rotary compensator.
Through reasonable measures such as setting waveform parameters and fatigue life of bellows compensator, correct device and perfect stress analysis of pipe system, the stability title of bellows can be handled. The title of corrosion title can be treated in two ways:
(1) Reasonable corrugated pipe material selection and compensator structure design can block the corrosion source.
(2) Strengthen the management of ponding in the chamber, and basically deal with the title of corrosion.