3、 CTOD (Crack Tip Opening Displacement) test As mentioned above, the welded joint of the all welded valve body pipeline pneumatic ball valve body is the biggest hidden danger for the integrity of the valve pressure boundary. However, the Charpy impact test, the traditional test method for evaluating the toughness of welded joints, is actually an indicator to measure the impact resistance of welded joints, It can not fully reflect the true toughness of welded joints, nor can it explain the failure mechanism of welded joints, nor can it reflect the impact of welding residual stress, geometric size constraints of welded joints and other factors on toughness. Therefore, the Charpy impact toughness value used to evaluate the toughness of welded joints has obvious limitations.

The compensator has the following advantages:
1. Compensate the axial, transverse and angular thermal deformation of absorption pipe.
2. The expansion and contraction amount of the corrugated compensator is convenient for the installation and disassembly of the valve pipeline.
3. Absorb equipment vibration, and tetrafluoro compensator reduces the impact of equipment vibration on pipeline.
4. Absorb the deformation of pipeline caused by earthquake and ground subsidence.