Non-Destructive Testing (NDT) Practice Test

Which NDT technique is primarily used to detect surface and near-surface defects utilizing a magnetic field?

1. Ultrasonic Testing

2. Radiographic Testing

3. Magnetic Particle Testing

4. Visual Inspection

The correct answer is: Magnetic Particle Testing

Magnetic Particle Testing (MPT) is specifically designed to detect surface and near-surface defects in ferromagnetic materials. This technique utilizes a magnetic field to identify defects such as cracks, laps, and seams that may not be visible to the naked eye. In MPT, the test object is magnetized, and fine magnetic particles are applied. When these particles are introduced to a magnetic field, they tend to align along the magnetic field lines. If there are any surface or subsurface defects present, the magnetic field will leak out at the defect, causing the particles to accumulate and form a visible indication of the defect's location and shape. This ability to highlight flaws effectively makes Magnetic Particle Testing a widely utilized method in various industries, particularly in stress-related applications or where components are subject to fatigue. The other testing methods do not focus primarily on surface and near-surface defects in the same way that MPT does. For instance, Ultrasonic Testing employs high-frequency sound waves to detect internal flaws, while Radiographic Testing uses X-rays or gamma rays to image the internal structure of a material. Visual Inspection depends entirely on the inspector's ability to see surface conditions without the aid of magnetic fields or other mechanisms. Each of these methods has its own