STRUCTURE CHARACTERISTICS AND DEFECT ANALYSIS OF THREE LAYER COATING SYSTEM

Three layer system (3PE) exhibits well the excellent protection performance of polyethylene material.However,compared with other kinds of coatings,the application process of 3PE is more complicated.There will be various defects or faults in the coating if the coating process is not controlled properly.Furthermore,some of the defects in 3PE may cause damages more severe than in fusion bonded epoxy since a strong shielding effect from cathodic current exists at the spot under the disbonded 3PE coating.In this article,the constitution characteristics of 3PE are discussed,and the causes and countermeasures for defects in application process are introduced.