🔍 Key Concepts

• Ultrasonic testing (UT) and what type of flaws it is especially good at detecting • Difference between checking thickness/clearances/wear versus checking internal defects • Common shipyard uses of UT on hull structures and welded joints

💭 Think About

• Ask yourself: Does ultrasonic sound energy work better for measuring external gaps/clearances, or for finding hidden flaws inside metal? • Which of these choices involves looking inside solid steel rather than measuring movement, clearance, or surface wear? • Think about where surveyors commonly use the same UT instrument when they finish checking shell-plate thickness on a vessel in drydock.

✅ Before You Answer

• Identify which choice deals with internal conditions within metal instead of external gaps or mechanical clearances. • Eliminate any options that mainly involve mechanical movement, bearing wear, or free play rather than internal flaws. • Confirm that the remaining option is a standard shipyard/survey application of UT you might see during repairs or class surveys.