Discontinuity measurement uncertainty evaluation using the Feeler PIG

The Feeler PIG is equipment that uses a geometric sensor to carry out the internal inspection of piping of different sizes. Several experiments on laboratory benches were carried out to evaluate the measuring accuracy of the Feeler PIG, considering a rotating metallic disk with discontinuities machined in its body and a single sensor for the detection of defects. The present work aims to study the measurement uncertainties with the Feeler PIG, through a laboratory experiment, comparing the results found by the device measurements, in a pipe with a nominal diameter of 6” in PVC, with synthetic discontinuities made in a calibrated 3D printer in a laboratory. The tests were based on the operational use of the PIG, in which it moves inside the pipe under different speed conditions and with an arrangement of synthetic discontinuities with 5 different geometries. The methodology used was the same performed in a calibration laboratory, in which the sum of type A and B uncertainties are multiplied by the coverage factor (k), which proved capable of reaching expanded uncertainties of the order of ± 3.1% to 5.0% using a confidence level of 95.45%.