In Oil and Gas plant facilities, protective coating system selection for cyclic temperature condition and under insulation has become a key concern in recent years. Severe cyclic temperature conditions in LNG plant facility is observed in Dehydration Unit where operating temperatures ranges from +25 °C to +300 °C with a few cycles per day, for carbon steel components with and without insulation.
In such severe conditions, there are few protective coating systems available for carbon steel surfaces. NACE(1) Standard SP01981, “The Control of Corrosion Under Thermal Insulation and Fireproofing Materials – A Systems Approach”, includes such as TSA: Thermal Spray Aluminum (CS-5), IMM: Coating with Inert Multi-Polymeric Matrix (CS-6) or IOZ: Inorganic Zinc Primer with topcoat (CS-8).
These protective coating systems will be applied at several locations such as vendor shops, module yards and shops/fields at construction sites. After completion of coating works, these articles are exposed to corrosive atmospheric environment during storage, transportation and construction until plant start-up, typically after a couple of years. Thus, consideration must also be given to the protective coating durability at ambient temperature in corrosive environments.
A comparison between “TSA”, “IMM”, and “IOZ with IMM”, with respect to both cyclic temperature heat resistance and ambient temperature corrosion protection is investigated in this paper.
In conclusion, it is suggested that “TSA” and “IOZ with IMM” are optimum protective coating system for cyclic temperature service in coastal area corrosive environment. In addition, IMM without IOZ may also be applied with sufficient evaluation beforehand.
Keywords: Coating, Paint, Cyclic temperature, Coating with Inert Multi-Polymeric Matrix, Thermal Sprayed Aluminum, CUI, Heat Cycling Test, Salt Spray Test