Visual Testing (VT) - Level II Study Guide
Core concepts
Visual testing is examination by the eye, alone or aided by optical instruments, and it underpins every other method because a surface must be seen before it can be tested. Understand direct versus remote viewing, lighting requirements, contrast and resolution, magnification aids, viewing angle, and equipment such as borescopes, fiberscopes, magnifiers, and cameras. Know the near-vision requirement of Jaeger 1 or equivalent at 12 in (305 mm), checked annually, and the requirement for adequate illumination at the inspection surface.
Traps to expect
- Poor lighting is the most common cause of missed indications; inspectors often blame technique when light is the real problem.
- Viewing far from the surface normal hides tight cracks through glare and shadow; stay within about 30 degrees of normal.
- Remote inspection loses depth perception and resolution, so a positive indication should be confirmed directly when possible.
- Scale, paint, dirt, and weld spatter hide discontinuities; cleaning is part of the technique.
- Surface finish and lighting angle create false indications from reflections.
- Documentation matters: record lighting conditions and equipment used.
Rule of thumb
Provide at least about 100 foot-candles (roughly 1,075 lux) at the inspection surface and view within 30 degrees of the surface normal.
Worked example: a weld shows no cracks under ambient shop light, then reveals linear indications under a bright, angled light. The first result was invalid because illumination was inadequate, not because the weld was sound.