A cyclic-temperature environment is recognized as a severe condition for coatings. In oil and gas plant facilities a dehydrator is a typical kind of equipment operating in the most severe cyclic-temperature environment ranging from ambient to 300 deg-C. For a dehydrator, three coatings (i.e., "a heat resistant silicone liquid coating", "an inorganic copolymer or coatings with an inert multipolymeric matrix liquid coating" or "a thermal sprayed aluminum coating") are typically applied.
However, no experimental data comparing the performance of these coatings, i.e., heat cycle stability and corrosion resistance, under standard test conditions have been reported. Furthermore, no standard test method has been established to evaluate the coating performance in a cyclic-temperature environment ranging from ambient temperature to 300 deg-C.
This paper summarizes an overview of coatings for a cyclic-temperature environment first, and proposes a simple test method which includes a heat cycle between 21 to 300 deg-C simulating the dehydrator operation and exposure to salt spray. The performances of the three coatings were evaluated using this method. Finally, based on the test results and on information from recent process plant construction projects, factors to be considered for coating selection in the cyclic-temperature environment are discussed.
Keywords: downloadable, Cyclic-temperature, dehydrator, cycling, inorganic copolymer or coatings with an inert multipolymeric matrix, thermal sprayed aluminum, TSA, salt spray test, cathodic protection, blackening