Which device is commonly used to measure coating thickness in the field?

• A. Ultrasonic thickness gauges
• B. Infrared cameras
• C. X-ray fluorescence devices
• D. Differential scanning calorimeters

Answer: (A)

Measuring coating thickness in the field is done with a tool that uses ultrasonic waves to determine how thick a coating is on a surface. Ultrasonic thickness gauges emit a high-frequency pulse into the coating and then measure the time it takes for the echo to return from the coating–substrate interface. Using that travel time and the known speed of sound in the coating (or in the substrate, with proper calibration), the instrument calculates the coating thickness. This method works on many substrates, handles curved or irregular surfaces, and is non-destructive, portable, and relatively quick—making it ideal for on-site inspections of pipelines, tanks, and structures. It also doesn’t rely on the coating’s color or appearance, which is a big advantage in the field.

Infrared cameras, by contrast, map surface temperatures and heat patterns rather than physical thickness. X-ray fluorescence devices can measure some coating thicknesses but require safety precautions, calibration, and are not as universally practical for quick field checks. Differential scanning calorimeters are laboratory instruments used to study material properties like heat flow, not field coating thickness.