Analysis of the couplant influence on the ultrasonic thickness measurement of the steel grade S355J0

The ultrasonic thickness measurement is the most commonly performed technique as a part of quality management of systems and constructions. The paper carries out a study of the couplant impact on the wall thickness ultrasonic measurement results. Experimental samples are made from the steel grade S355J0. By performing a theoretical and experimental analysis, it estimates that there exists a significant effect of the particular parameters of the ultrasound transducer, the couplants type and their interactions on the thickness measurement results. An experiment scheme and the appropriate methodology for experimental results analyses create the preconditions for the assessment of the influence of the couplant type, material thickness and the parameters of ultrasound probe to the measurement uncertainty.