Non-destructive testing (Non-Destructive Testing, abbreviated as NDT) is an important technical means for evaluating the internal structure, material properties, and potential defects of the inspected object without damaging it. It is widely used in many fields such as aerospace, pressure vessels, bridge construction, railway transportation, and energy equipment. In practical applications, how to scientifically and reasonably select appropriate non-destructive testing methods is the key to ensuring the accuracy and efficiency of detection results.



1. Choose methods based on the material and structure of the inspected object



Different materials have different sensitivities to different testing methods. For example:



- Metallic materials: suitable for magnetic particle testing (MT), ultrasonic testing (UT), radiographic testing (RT), and eddy current testing (ET).



- Non-metallic materials (such as composites, ceramics): it is more suitable to use ultrasonic or infrared thermal imaging testing.



- Weld joints: ultrasonic testing or radiographic testing is commonly used to check internal defects such as pores, slag, and incomplete fusion.

　　- Surface crack-like defects: magnetic particle testing or penetrant testing (PT) is more suitable.



2. Choose methods based on defect type and location



Different testing methods have different detection capabilities for different types of defects:



- Surface defects (such as cracks, folds): it is recommended to use magnetic particle testing (MT) or penetrant testing (PT);



- Near-surface defects: eddy current testing (ET) is more appropriate;



- Internal defects (such as pores, inclusions, un熔合): ultrasonic testing (UT) and radiographic testing (RT) are the preferred methods;



- Internal defects in large components: ultrasonic or acoustic emission testing (AE) technology can be considered.

　　3. Choose methods based on detection environment and equipment conditions



When choosing testing methods, it is also necessary to consider the limitations of the on-site environment and equipment conditions:



- If there is a strong magnetic field interference in the detection site, it is not suitable to use magnetic particle testing;



- If the working space is small or the component shape is complex, it may limit the application of radiographic testing;



- Detection cost, efficiency, and the skill level of the operators are also important considerations when choosing methods.



4. Improve detection reliability by integrating multiple methods



Single testing methods often have limitations. It is recommended to use a combination of multiple methods for important structures or high-risk areas to complement each other and improve detection accuracy. For example, combining ultrasonic and radiographic testing can provide a more comprehensive understanding of the quality condition of weld joints.



Conclusion



In summary, the selection of non-destructive testing methods should be based on a comprehensive evaluation of the specific conditions of the inspected object, defect types, detection environment, and resource conditions. Only by scientifically and reasonably selecting suitable testing methods can the detection quality be effectively guaranteed, and the safety and reliability of equipment operation can be improved. In actual work, detection personnel should continuously accumulate experience and improve their judgment ability to ensure the safety of engineering projects.