What are the 4 types of NDT?

Four Types of Non-Destructive Testing (NDT)

Non-Destructive Testing (NDT) is a group of analysis techniques used in science and industry to evaluate the properties of a material, component, or system without causing damage. The following are four primary types of NDT:

1. Ultrasonic Testing (UT)

Ultrasonic Testing uses high-frequency sound waves to detect imperfections or changes in the properties of materials. It is commonly used to find defects in welds and to measure the thickness of materials. A transducer connected to a diagnostic machine is passed over the object being inspected. The sound waves travel through the material and reflect back to the transducer, which converts them into electrical signals that can be interpreted.

2. Radiographic Testing (RT)

Radiographic Testing involves the use of X-rays or gamma rays to view the internal structure of a material. This method is particularly useful for identifying and quantifying internal defects such as cracks, voids, and porosities. It is widely used in the aerospace and automotive industries for quality control and in the construction industry for inspecting structural components.

3. Magnetic Particle Testing (MPT)

Magnetic Particle Testing is a method used to detect surface and near-surface discontinuities in ferromagnetic materials such as iron, nickel, and cobalt. The process involves magnetizing the material and then applying ferrous particles to the surface. The particles will gather at areas of flux leakage, indicating a flaw. This method is highly effective for detecting surface cracks.

4. Liquid Penetrant Testing (LPT)

Liquid Penetrant Testing is a widely applied inspection method used to locate surface-breaking defects in all non-porous materials (metals, plastics, or ceramics). The test involves applying a liquid with high wetting characteristics to the surface. The liquid penetrates into the clean surface breaking defects and is then drawn out by a developer, making the defect visible. LPT is simple to apply and highly sensitive to small surface discontinuities.

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