Ultrasonic thickness gauges permit the measurement of material thickness without making physical contact, using sound wave reflection. Their time-Of-Flight thickness calculation (0.01 mm resolution) makes it possible to use them on rugged surfaces that are hard to reach, including ceramics, metals, and composites. API 510 and ASME BPVC pressure vessel inspection standard Industrial models employ dual element probes for rough surface application and thermal expansion compensation of 1x10^-5/°C.
