Experimental evaluation of high solid polyurethane coating in the presence of salt at high temperature

Ions' presence and high temperature affect the performance and service life of all types of coatings including pipeline coatings. Pipeline coatings are relatively thick and their evaluations are very time consuming. In this study, experiments on the thick coating samples (roughly 250 and 400 µm) of high solid polyurethane (HSPU) have been conducted to evaluate the effect of high temperature and presence of ions in the media, on the performance of coatings. The experiments were performed in two types of electrolytes, sodium chloride solution (3.5 wt% fraction) and distilled water, at two temperature levels of 25 and 75 °C, respectively. The coating performance was studied using electrochemical spectroscopy impedance (EIS) method. The results of experiments show that the presence of ions reduces the service life of the coating and higher temperature accelerates the degradation process further if oxygen is not limited.