Mechanical hazards to stack coatings

The use of a wet stack requires protective coatings to prevent corrosion of the inner surface of flue gas ducts. The corrosion may arise in result of flue gas cooling below the dew point as well as in presence of hygroscopic and deliquescent salts. Different technologies are used to serve this purpose, such as composite coatings. This paper presents the mechanical and thermal resistance testing of the ARC 982 composite coating. The testing was comprised of: • assessment of specimen bending at a specific angle in terms of the occurrence of coating exfoliation, • assessment of the probability of metal exposure due to the impact of tools on the coating, • assessment of the effect of welding in the area without the composite on the state of the coating.The results of the performed tests prove that both bending (even at a small angle) and a hammer impact may lead to composite coating cracking and exfoliation from the metal plate. They also prove that if coated metal plates are welded in some conditions, the allowable temperature for the ARC 982 material may be exceeded.