Abstract
Thermally insulated steel surfaces are very challenging with respect to corrosion protection for several reasons. High temperature and temperature cycling is generally demanding for protective organic coatings. Moisture frequently penetrates the insulation mantling and provides a very corrosive environment. The mantling also prevents the moisture to escape, and the corrosive environment is trapped. Finally, the insulation prevents efficient inspection of the state of the coating. Hence, corrosion can develop to a severe state without being discovered. Selecting suitable coating products are therefore important, and methods for testing coating resistance to degradation under thermal insulation are sought. A test method was presented by Halliday in 2005,1 which has been used in this work. Four different coatings have been tested: Thermally Sprayed Aluminium (TSA), an amine cured epoxy, an epoxy novalac and a temperature resistant inorganic paint. In the method the sample has a temperature gradient, so the coating is exposed to temperatures from ambient to 400 °C. In addition the temperature is cycled and a corrosive electrolyte is added. The paper discusses the test method and performance of the coatings as function of temperature exposure, temperature gradient along the sample and coating properties.