1. Test Method Figure 2 The CTOO test is based on the BS7448 Part 2 test standard, API 1104 and DNV-OS-401 related specifications and requirements, and the CTOD fracture toughness value is used to evaluate the safety of all welded valve body welded joints in post weld heat treatment free. As shown in the figure, according to BS7448 Part 2, the thickness of the sample is B=18, the width W=36, the length L=4 36 ＋ 20, and the crack length a ≈ (0.04~0.55) W. Prefabricate cracks with a fatigue testing machine. Conduct the test with the original CTOD test hardware system and control program on the American 500KN MTS testing machine, and measure the crack growth with a 6-bit (0.00001mm) high-precision digital reading microscope. According to the best method confirmed by the standard, the multi sample method is used to obtain the notch opening displacement of critical cracking; C (or; 0.05).

4、 Features of pneumatic ball valve:
The pneumatic ball valve is mainly used to cut off or connect the medium in the pipeline, and can also be used to regulate and control the fluid. Compared with the pneumatic control valve and other types of valves, the pneumatic ball valve has the following advantages: angular travel output torque, rapid, stable and reliable opening, wide application, etc.