Types of Non-Destructive Testing (NDT) Available in the Market
1. Ultrasonic Testing (UT)
– Applications*: Detects internal flaws and measures material thickness.
– Method: High-frequency sound waves are transmitted into the material, and reflections from flaws are detected.
2. Radiographic Testing (RT)
– Applications: Inspects welds, castings, and structural components.
– Method: Uses X-rays or gamma rays to create images of the internal structure of a component.
3. Magnetic Particle Testing (MT)
– Applications: Detects surface and near-surface defects in ferromagnetic materials.
– Method: Magnetic fields are applied to the material, and iron particles are used to visualize defects.
4. Liquid Penetrant Testing (PT)
– Applications: Identifies surface-breaking defects in non-porous materials.
– Method: A dye penetrant is applied to the surface, then removed, and a developer is applied to draw out the dye from defects.
5. Eddy Current Testing (ET)
– Applications: Detects surface and sub-surface defects in conductive materials.
– Method: An alternating current is passed through a coil, producing an electromagnetic field that induces currents in the material.
6. Visual Inspection (VI)
– Applications: General inspection for surface defects and conditions.
– Method: Direct visual examination, often using tools like magnifying glasses, borescopes, and mirrors.
7. Acoustic Emission Testing (AET)
– Applications: Monitors the release of energy from a material under stress.
– Method: Detects transient elastic waves produced by sudden structural changes.
8. Thermographic Testing (TT)
– Applications: Detects thermal anomalies related to defects.
– Method: Uses infrared cameras to detect heat variations on the surface of materials.
9. Leak Testing (LT)
– Applications: Detects leaks in pressure systems and sealed components.
– Method: Various methods, including pressure decay, bubble testing, and halogen diode testing, are used to identify leaks.
10. Phased Array Ultrasonic Testing (PAUT)
– Applications: Advanced form of UT for detailed imaging.
– Method: Uses multiple ultrasonic elements and electronic time delays to create a detailed cross-sectional image.
11. Time-of-Flight Diffraction (TOFD)
– Applications: Accurate flaw detection and sizing, particularly in weld inspections.
– Method: Measures the time of flight of ultrasonic pulses reflected from defects.
12. Resonant Testing (RT)
– Applications: Detects changes in material properties and defects.
– Method: Measures the natural frequency response of a component.
13. Computed Tomography (CT)
– Applications: Detailed 3D imaging of internal structures.
– Method: Uses multiple X-ray images taken from different angles to create a 3D model.
Each of these NDT methods offers unique advantages and is suited for different applications and materials. The choice of NDT technique depends on the specific requirements of the inspection, including the type of material, the nature of the potential defects, and the required level of accuracy and detail.