When applying a coating system to structures such as tanks and pipelines, the primary goal is to apply a continuous film to help prevent corrosion and section loss, and in some cases, to prevent contamination of the contents. Discontinuities in the film can result in undercutting corrosion of the substrate, and the integrity of the structure could potentially be compromised. Holiday or pinhole detection is used to detect voids in the applied coating or lining. While pinholes and holidays may be visually evident, their detection is made simpler using low voltage (wet sponge) or high voltage (spark testing) holiday detectors. Proper selection of the detector based on coating thickness, set-up (voltage setting for high voltage detection), and operation helps ensure proper testing without adversely affecting the properties of the coating.
Test your knowledge of holiday/pinhole detection by challenging each of the questions below. Helpful references are included in the text box below each question. The answers to the questions and links to KTA products/services to help you in the shop or field are provided at the end of the question bank.