Non-Destructive Testing and Inspection
Visual testing, liquid penetrant, magnetic particle, ultrasonic, and radiographic inspection methods.
- Describe visual testing and liquid penetrant testing procedures
- Explain magnetic particle inspection and its material limitations
- Compare ultrasonic and radiographic testing capabilities
- Describe destructive testing methods including bend, tensile, and CVN
Lección 1
Visual and Liquid Penetrant Testing
Visual Testing (VT)
VT (Visual Testing) is the most basic and most frequently used inspection method. It requires no special equipment beyond good lighting, a measuring device, and the inspector's eyes. VT should be performed before, during, and after welding to catch issues early.
VT can detect surface discontinuities including undercut, overlap, porosity, cracks, incomplete fusion, excessive reinforcement, and dimensional deviations.
Liquid Penetrant Testing (PT/LPI)
PT (Penetrant Testing) or LPI (Liquid Penetrant Inspection) detects surface-breaking discontinuities. It works by applying a brightly colored or fluorescent liquid to the surface. The liquid is drawn into any cracks or openings by capillary action. After removing excess penetrant, a developer is applied that draws the trapped penetrant back out, creating a visible indication.
PT Limitation
Liquid penetrant testing can only detect surface-breaking discontinuities. It cannot find subsurface defects. PT works on any non-porous material - ferrous, non-ferrous, ceramics, and plastics.
VT is the most common inspection method and should be done on every weld. PT/LPI detects surface-breaking discontinuities using capillary action. PT works on all non-porous materials but cannot find subsurface defects.