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Visual Testing Instructor Guide l LESSON 1
4. Endoscopes—the word derives from the Greek words for “look inside”—were used in medicine to look in
the interior of the human body.
5. George S. Crampton, a physician, transferred the use of borescopes from medical to industrial
applications.
6. In 1921, Crampton developed the first borescope for Westinghouse Company to check for discontinuities
inside a steam turbine.
7. A similar patent was filed separately in 1927 for a borescope to inspect the inside of gun bores (Figure 1).
8. During World War II, Crampton actively supported the US Army by checking the bores of antiaircraft
guns.
Overview of VT Applications: Capabilities and Limitations
1. Visual testing is done in all stages of the “life” of a component or machine, during and after manufacture
as well as at regular intervals during service.
2. Very often, testing is performed in two steps:
l Overview or general visual testing: screening for anomalies done at a lower sensitivity (illumination
and magnification).
l Local or detailed visual testing: verification and characterization of anomalies at a higher sensitivity
(illumination and magnification) in order to determine if they are acceptable or must be rejected.
Figure 1: Drawing from a patent for a borescope for gun barrels.
Visual Testing Instructor Guide l LESSON 1
4. Endoscopes—the word derives from the Greek words for “look inside”—were used in medicine to look in
the interior of the human body.
5. George S. Crampton, a physician, transferred the use of borescopes from medical to industrial
applications.
6. In 1921, Crampton developed the first borescope for Westinghouse Company to check for discontinuities
inside a steam turbine.
7. A similar patent was filed separately in 1927 for a borescope to inspect the inside of gun bores (Figure 1).
8. During World War II, Crampton actively supported the US Army by checking the bores of antiaircraft
guns.
Overview of VT Applications: Capabilities and Limitations
1. Visual testing is done in all stages of the “life” of a component or machine, during and after manufacture
as well as at regular intervals during service.
2. Very often, testing is performed in two steps:
l Overview or general visual testing: screening for anomalies done at a lower sensitivity (illumination
and magnification).
l Local or detailed visual testing: verification and characterization of anomalies at a higher sensitivity
(illumination and magnification) in order to determine if they are acceptable or must be rejected.
Figure 1: Drawing from a patent for a borescope for gun barrels.