Ultrasonic
Thickness from time of flight
Thickness from the round-trip transit time and the velocity, or the transit time a thickness should give.
For reference only — verify against your procedure and the governing code.
ASTM E494 Table X3.1 typical values, converted from the source's m/s.
Result
- Thickness
- 25mm
Formula
- T = V · t / 2 (t = round-trip transit time)
Units. Computed in m/s and mm (velocity in m/s × time in µs ÷ 2000 = mm); shown in mm/µs and mm, or in./µs and in.
Assumptions and limits
- Pulse-echo, with the instrument's zero offset already removed from t.
- Velocity is the biggest error source: calibrate on the same material at the same temperature where accuracy matters (ASTM E797).
Sources
- ASTM E797/E797M-15, Standard Practice for Measuring Thickness by Manual Ultrasonic Pulse-Echo Contact Method — §4.1, T = Vt/2.
- ASTM E494-20, Standard Practice for Measuring Ultrasonic Velocity in Materials — Appendix X3, Table X3.1 (typical values).
More ultrasonic calculators
For reference only — verify against your procedure and the governing code.
Standards and documents are cited by their publishers' names to identify them. TRACE is not affiliated with, endorsed by or sponsored by ASTM International, ASME, the U.S. Nuclear Regulatory Commission, NIST or the Laboratoire National Henri Becquerel. Formulas are paraphrased and cited by clause; get the documents themselves from their publishers.