Visual inspection (VT)
Visual inspection (VT) is one of the oldest NDT techniques.
With visual inspection, the inspector searches for defects with the naked eye or by using various instruments. This technique is used for both internal and external surface inspections and on many different materials.
Visual inspection is the simplest of all NDT techniques. Nevertheless, visual inspection offers some significant advantages over other methods.
With visual inspection the tester makes use of different tools to look at the test object. Examples are magnifying glasses, mirrors or boroscopes.
Visual inspection is recommended for detecting cracks, physical damage, alignment faults or corrosion on a wide variety of objects in different materials:
At which stage do we use visual testing?
Visual testing (VT) is used in each phase of the life cycle of a product:
- forged parts
- castings
- machined objects
- welds
The advantages and disadvantages of visual testing
Advantages:
- low testing costs
- little or no preparation of the surface to be tested required
- immediate interpretation of indications
- use of portable equipment (if necessary) is sufficient
Disadvantages:
- only for use on visible surfaces
- detectable errors must be large enough
- the interpretation of faults is not always true and may therefore be wrong, e.g. scratches
In which industry do we use visual inspection?
Industries in which visual inspection is used:
- construction steel
- petrochemistry
- oil, gas and wind industry, onshore and offshore
- shipping industry
