Effect of application process and physical properties of penetrant material to the sensitivity of liquid penetrant inspection

Abstract

Liquid Penetrant Testing is one of the most popular and widely used NDT method in a wide range of industries such as oil & gas, power generation, aerospace, marine and automotive. It can be used to detect open to surface defects on all non-porous materials. Solvent removable visible dye penetrant testing is employed in this project. Reliability of using dye penetrants that have elapsed their manufacturer-recommended usable time for liquid penetrant testing, is presented in this paper. There are two main parts in this study; comparing the sensitivity of dye penetrants by varying inspection techniques, and comparing the physical properties of penetrant materials. Four color contrast dye penetrant samples, with different chemical aging, were selected to perform the tests. For the first part, penetrant testing was performed on two selected welding discontinuities by varying dwell time and the number of developer layers with the aid of selected dye penetrant samples. For the second part, the density and viscosity of each dye penetrants were measured. According to the results, sensitivity and detectability of solvent removable visible dye penetrant decreases with the chemical aging. However, with increased dwell time and a minimal number of developer layers, it can be used to detect volumetric defects. With chemical aging, density does not change significantly but viscosity can be changed with different thermal and environmental influences.