EFFECT OF ANTI-CORROSION PROTECTIVE PAINT ON THERMOGRAPHIC INSPECTION OF CURVED STEEL TUBE PARTS

Abstract

The use of anti-corrosion paint coatings on steel pipes is a common practice for their protection against corrosion. However, such coatings may have an impact on the results of the thermographic inspection, which can be used, for example, for their corrosion damage identification. In this study, we investigated the influence of anti-corrosion paint on the thermographic inspection of curved steel tube parts. Long pulse thermography inspection was conducted on painted and unpainted samples, and the results were compared. It was found that the used painting reduced the absorbed energy, however, the contrast of the found defect indications was better on painted samples. The experiments indicated that any inhomogeneity of an inspected surface due to, for example, the painting process, the presence of old painting layers, or the presence of surface corrosion, can cause irregular surface absorption patterns. It can result in signals from this unevenness that can reduce the contrast of the indications of defects. These findings can have significant implications for the use of thermography as a non-destructive testing technique for curved steel tube parts, for example, steel pipes, especially those in operation with correction paint or corrosion layers