Non-destructive testing is an applied technical discipline based on modern science and technology. It uses sound, heat, electricity, magnetism, ray, etc. to interact with the detected substances without damaging the internal structure and applicable properties of the detected substances. In this case, to detect microscopic or macroscopic defects existing inside or on the surface of the object such as materials, components or equipment, and to determine its position, size, shape and type.

Therefore, the properties of the material to be tested under ray radiation; the properties exhibited by the elastic wave; the electrical, magnetic, thermal, surface energy and subtle changes of the material properties of the material become non-destructive testing techniques. The basics. That is to say, non-destructive testing is the principle of causing changes in physical quantities when the internal structure and structure of the material are abnormal. In turn, the change in physical quantity is used to infer the abnormality of the organization and structure of the material inside the electric valve. The non-destructive testing commonly used for electric valves is radiation detection.

The methods of radiation detection include photographic method, fluorescent display method, television observation method, and ionization recording method. The flaw detection rays have high-energy X-rays generated by X-rays, Y-rays, and electron linear accelerators. It can detect cracks, inclusions, shrinkage and shrinkage in the workpiece, non-weld, unfused in the weldment, etc., and has high sensitivity to volumetric defects. The judgment of defects is less affected by human factors. The defect image is intuitive, and the result is better recorded, but the operation is more complicated and the cost is higher.