Application characteristics and purpose of common nondestructive testing technology for components

Date：2021-08-11 17:29:00 Views：1817

Nondestructive testing is defined as the method of inspecting and testing the structure, properties and state of the internal and surface of the test piece by means of physical or chemical methods and with the help of advanced technology, equipment and equipment without damaging the test piece. Nondestructive testing technology is widely used in industry, such as aerospace, nuclear industry, weapon manufacturing, machinery industry, shipbuilding, petrochemical industry, railway and high-speed train, automobile, boiler and pressure vessel, special equipment, customs inspection and so on. So, what are the application characteristics of nondestructive testing technology?

Nondestructive testing technology is mainly used for the inspection of unknown process defects. It is a supplement and improvement to destructive inspection. It is characterized by:

① Non destructive means that no parts are lost except unqualified products are removed while obtaining the test results. Therefore, the inspection scale is not limited by the number of parts. It can not only be sampled for inspection, but also be subject to general inspection when necessary. Therefore, it has more flexibility (general inspection and sampling inspection) and reliability.

② Compatibility - refers to the compatibility of inspection methods, that is, the same part can adopt different inspection methods at the same time or in turn; And the same test can be repeated. This is also the benefit of non-destructive.

③ Dynamic - this means that NDT can inspect parts in use and timely investigate the cumulative impact of product operation period. Therefore, the failure mechanism of the structure can be found out.

④ Strictness - refers to the strictness of NDT technology. First, NDT requires special instruments and equipment; At the same time, specially trained inspectors are also required to operate in accordance with strict procedures and standards.

⑤ Divergence of inspection results - different inspectors may have different inspection results for the same specimen. Especially in ultrasonic inspection, the same inspection item shall be completed by two inspectors.

To sum up, the characteristics of nondestructive testing are: non-destructive, mutual compatibility, dynamics, strictness and divergence of testing results.

Purpose of NDT

1. Ensure product quality

2. Ensure use safety

3 reduce production costs

4 improve manufacturing process

Application characteristics of nondestructive testing

1 nondestructive testing shall be coordinated with destructive testing

2. Correctly select the time for nondestructive testing

3. Correctly select the most appropriate NDT method

4 comprehensive application of various NDT methods

Nondestructive testing instruments include not only the five conventional methods (radiographic flaw detector, ultrasonic flaw detector, magnetic particle flaw detector and penetrant), but also other hardness testing instruments, thickness measuring instruments and various shape testing instruments (ruler, gauge, etc.). It also includes various auxiliary instruments and equipment, such as blackness meter and dosimeter for radiographic testing. Of course, any nondestructive testing method has its own advantages and disadvantages, which is not omnipotent. Enterprises should use several testing methods as much as possible to learn from each other, so as to ensure the safe operation of pressure equipment.