Principle and application characteristics of nondestructive testing technology commonly used in industry

Date：2021-09-08 11:35:39Views：1312

Nondestructive testing is to use the acoustic, optical, magnetic and electrical properties of materials to detect whether there are defects or non-uniformity in the tested object without damaging or affecting the service performance of the tested object, and give information such as the size, location, nature and quantity of defects. Nondestructive testing can find defects in the interior and surface of materials or workpieces, measure the geometric characteristics and dimensions of workpieces, and determine the internal composition, structure, physical properties and status of materials or workpieces. What are the characteristics of NDT? What is the principle?

Nondestructive testing includes many effective methods. The most commonly used NDT methods are radiographic testing, ultrasonic testing, eddy current testing, magnetic particle testing, penetrant testing, visual testing, leakage testing, acoustic emission testing, radiographic testing, etc. Because all kinds of NDT methods have their own scope of application and limitations, new NDT methods have been continuously developed and applied. Generally, as long as the basic definition of NDT is met, any physical, chemical or other possible technical means may be developed into an NDT method.

Application characteristics of nondestructive testing

1. Do not damage the material and structure of the test piece

The biggest feature of nondestructive testing is that it can be tested without damaging the material and structure of the test piece. Therefore, after the implementation of nondestructive testing, the inspection rate of the product can reach 100%. However, not all items and indicators that need to be tested can be subject to nondestructive testing, and nondestructive testing technology also has its own limitations. Some tests can only use destructive tests. Therefore, nondestructive testing can not replace destructive testing at present. In other words, for the evaluation of a workpiece, material, machinery and equipment, the results of nondestructive testing and destructive test must be compared and matched with each other in order to make an accurate evaluation.

2. Correctly select the time for NDT

During NDT, the timing of NDT implementation must be correctly selected according to the purpose of NDT.

3. Correctly select the most appropriate NDT method

Since various testing methods have certain characteristics, in order to improve the reliability of testing results, appropriate nondestructive testing methods shall be selected according to the types, shapes, positions and orientations of possible defects according to equipment materials, manufacturing methods, working media, service conditions and failure modes.

4. Comprehensive application of various NDT methods

Any nondestructive testing method is not omnipotent. Each method has its own advantages and disadvantages. Several detection methods shall be used as much as possible to learn from each other to ensure the safe operation of pressure equipment. In addition, in the application of nondestructive testing, we should also fully realize that the purpose of testing is not to unilaterally pursue the "high quality" with excessive requirements, but to focus on its economy on the premise of fully ensuring safety and appropriate risk rate. Only in this way can the application of nondestructive testing in pressure equipment achieve the expected purpose.

In summary, in the field of Power System Research Institute, power construction company, light water reactor nuclear power plant, wind power station, shipbuilding industry, natural gas pipeline, CNOOC offshore pipeline inspection, PetroChina, Yanchang oil pipeline inspection, pressure vessel inspection, aircraft maintenance, aircraft parts suppliers, military metal products suppliers, steel structure weld inspection 3D printing products are widely used in these industries, which are closely related to nondestructive testing. In these industries that require product accuracy, product quality is particularly important. Therefore, it can not only detect the whole process of raw materials, intermediate process links and final products, but also detect the equipment used.