Principles of Nondestructive Evaluation Engineering

1. Visual Inspection


Visual inspection is the most basic form of NDE engineering, involving a visual examination of materials and structures to detect any visible defects.
It relies on the human eye or optical instruments to identify surface irregularities, cracks, corrosion, or other signs of damage.

2. Liquid Penetrant Testing


Liquid penetrant testing, also known as dye penetrant inspection, is a method used to detect surface-breaking defects. A coloured dye is applied to the surface, allowed to penetrate the defects, and then the excess dye is removed. A developer is applied, which makes the defects visible, aiding in their identification.

3. Radiographic Testing


Radiographic testing utilises X-rays or gamma rays to examine the internal structure of materials and components. It produces images called radiographs that highlight the presence of defects such as cracks, voids, or inclusions.
Radiographic testing is commonly used in industries like aerospace, oil and gas, and power generation.

4. Ultrasonic Testing


Ultrasonic testing employs high-frequency sound waves to detect internal flaws and measure the thickness of materials. A transducer generates sound waves that travel through the material, and reflections from defects or interfaces are detected. By analysing these reflections, NDE engineers can determine the presence and characteristics of flaws.

5. Eddy Current Testing


Eddy current testing uses electromagnetic induction to identify surface and near-surface defects in conductive materials. It involves passing an alternating current through a coil, which creates eddy currents in the material.
Any changes in the electrical conductivity or magnetic properties caused by defects result in detectable variations in the induced current.

6. Magnetic Particle Testing


Magnetic particle testing is a technique used to detect surface and near-surface defects in ferromagnetic materials.
The component under inspection is magnetised, and magnetic particles, often in the form of a suspension or dry powder, are applied. The particles gather at defect locations, indicating the presence of surface irregularities.