Intro to VT
What is another name for visual testing?
Visual Examination (VE)
What were early inspectors checking for inside boilers?
Corrosion and cracking
Why is VT considered low cost?
It needs very little money or expensive tools
VT can only detect ______ discontinuities.
Surface
Can tiny cracks always be seen with the naked eye?
No. Other NDT methods must be applie
What type of discontinuities can VT detect?
Surface discontinuities only
In what century did boiler inspection become an early use of VT?
The 1800s (late 1800s)
What does “portable” mean for VT?
It can be done in the field without heavy equipment
What is the biggest disadvantage of VT that relates to the inspector?
Human error
Name the two factors the slides call “key” to effective VT.
Contrast and illumination
Name one check done before welding.
Review drawings/specifications, check materials, fit-up, joint alignment, or storage of welding consumables
What did George S. Crampton develop in 1921?
The first borescope (to look inside a turbine)
Compared with other NDE methods, how much training does VT need?
Less training and preparation
Name two causes of human error in VT
Any two: missed flaws, exhaustion, glare, improper illumination
Name three human factors that limit how well VT works.
Eye exhaustion, visual access, mood
Name two checks done during welding.
WPS compliance, preheat/interpass temperature, root bead, intermediate weld beads, backside before welding
In 1927, a patent was filed for a borescope to inspect the inside of what?
Gun barrels (gun bores)
Name the two ways VT can be carried out in the field.
Direct visual testing and remote visual testing
A weld has a void inside it. Can VT find it? Explain why.
No. The void is subsurface, and VT only sees the surface
What is the difference between a disadvantage and a limitation?
A disadvantage is a weakness of VT compared with other methods. A limitation is a condition that restricts what VT can detect or how well it works
Give one reason to perform visual inspection before, one during, and one after welding.
Before: catch material, fit-up or alignment problems before welding starts, when they are cheapest to fix.
During: make sure the welder follows the WPS, and catch flaws in the root or intermediate beads before later passes cover them.
After: confirm the finished weld meets the required size, profile and surface quality.