1. Nominal size, connection type and flange standard.
2. Design pressure and temperature.
3. For the pressure thrust (blind plate force) generated by the medium, it is decided to use an unrestricted expansion joint or a constrained expansion joint.
4. Bellows material and heat treatment: mainly depends on the working medium. For high temperature steam heating network to prevent damage caused by stress corrosion, it is recommended to use 316L and solid solution treatment. For catalytic cracking high-temperature devices, it is recommended to use high nickel alloy and conduct annealing or solid solution treatment.
5. Fatigue life: consider the working times of bellows expansion joint.
6. Form of absorption displacement - axial, transverse and angular.
7. From the performance point of view, the internal pressure compensator can be displaced in three directions, but due to the limitation of casing and other accessories, it can only be displaced in axial direction. Therefore, the user needs to indicate the displacement in several directions when selecting and ordering, so as to select and supply correctly.
8. The axial type compensator is used to absorb the axial displacement of the pipeline, and the transverse displacement compensator absorbs the transverse displacement perpendicular to the axis of the compensator; The small tie rod lateral displacement compensator is suitable for absorbing lateral displacement, as well as axial, angular and any combination of three displacements; Two or three hinge compensators are used together to absorb the transverse deformation of a single plane in one or more directions; Universal hinge compensator can absorb displacement in multi plane system.
