Abstract:
Influence of external factors on accuracy of thickness measurements using digital ultrasonic gauges
L. Sozanski, Wroclaw (PL)
For thickness measurements especially in elements with one - side access, specialized ultrasonic thickness gauges analysing
passage time of ultrasonic wave are used. Years of practice have showed that apparent simplicity of measurements and
interpretation of results may lead to erratic evaluations of thickness, usually to its overestimating. The condition of the surface
where the probe is applied and geometry of the element under investigation (irregularities, corrosion and its products etc.)
have essential influence on accuracy and repeatability of results. For example a sand grain of 0.3 mm diameter being present
under the probe may cause an overestimating of the thickness of steel elements for more than 1 mm. Equally vital are
conditions of ultrasonic wave deflection on the boundary layer between material and ambient environment (gas, water, oil, ice)
which may also deform the results of measurements. In some cases use of universal defectoscopes, enabling wide analysis of
ultrasounds, is necessary to make measurements more reliable.