{"id":7761,"date":"2026-04-17T12:37:52","date_gmt":"2026-04-17T12:37:52","guid":{"rendered":"https:\/\/ultrasuonindt.it\/how-ultrasonic-thickness-measurement-works-the-basics-for-ndt-inspectors\/"},"modified":"2026-09-30T20:13:42","modified_gmt":"2026-09-30T20:13:42","slug":"how-ultrasonic-thickness-measurement-works-the-basics-for-ndt-inspectors","status":"publish","type":"post","link":"https:\/\/ultrasuonindt.it\/en\/how-ultrasonic-thickness-measurement-works-the-basics-for-ndt-inspectors\/","title":{"rendered":"How ultrasonic thickness measurement works: the basics for NDT inspectors"},"content":{"rendered":"\n

Ultrasonic thickness measurement is one of the most widely used NDT techniques in the world. It makes it possible to measure the thickness of a material from one side only<\/strong>, with no cuts, holes or other alterations. This basic guide explains the physical principles, the components of an ultrasonic instrument, the critical parameters and how they translate into a reading on the display. It is intended as an introduction for NDT inspectors at the start of their training<\/strong> and as a refresher for experienced technicians. <\/p>\n\n

\"Operating<\/figure>\n\n

The physical principle: pulse and echo<\/h2>\n\n

The principle is analogous to sonar<\/strong>. A piezoelectric transducer generates a short ultrasonic pulse (typically in the 1-20 MHz<\/strong> range) that travels through the material at that material’s characteristic velocity. When the pulse meets a boundary surface (back wall, flaw, interface), part of the energy returns as an echo. The transducer picks up the echo and converts it into an electrical signal. <\/p>\n\n

By measuring the time of flight<\/strong> between the transmitted pulse and the received echo, and knowing the speed of sound in the material, the instrument calculates the distance with the formula:<\/p>\n\n

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t = v \u00d7 \u0394t \/ 2<\/strong><\/p>\n\n

where the factor of 2 accounts for the pulse travelling the distance twice: there and back.<\/p>\n\n

Components of an ultrasonic instrument<\/h2>\n\n
\"Dakota<\/figure>\n\n

A complete gauge consists of:<\/p>\n\n