The basic and oldest non-destructive method for detection of surfacedefects on products, welds, components, and for the assessment of thecondition of individual parts of various facilities.

Visual inspection is commonly defined as “the examination of a material, component, or product for conditions of nonconformance using light and the eyes, alone or in conjunction with various aids.

Visual inspection often also involves, shaking, listening, feeling, and sometimes even smelling the component being inspected.

Visual inspection consists of at least two major processes:

The first is a search process

The second is a process of combining relevant knowledge, sensory input, and pertinent logical processes to provide an identification that some anomaly or pattern represents a flaw that poses a risk to the performance of the part.

Visual inspection is commonly employed to support other NDT methods.

Digital detectors and computer technology have made it possible to automate some visual inspections. This is known as “machine vision inspection.

It can be performed by direct or indirect methods during various stages of manufacturing or after thecomponent has been placed in-service.

Direct visual inspection:

    This inspection can be performed only on places, where theoperator can physically get into. The eyesight of the operatoris used during this method, respectively simple aids can beused (magnifying glass, gauges, camera etc.).

Indirect visual inspection:

    Places that are inaccessible for the eye of the operator areinspected with endoscopes (fixed or flexible).

The quality of an inspection are affected primarily byfour factors.

The quality of the detector (eye or camera).

The lighting conditions.

The capability to process the visual data.

The level of training and attention to detail.