Application of Thermally-Sprayed Coatings as Heat Tracers for Carbon Steel Pipes to Mitigate the Effect of Ice Accumulation and Freezing Damage

Abstract

The bursting of pipes due to freezing of contained liquid is considerably costly in industrial applications, resulting in over $4 billion in damage over the last decade alone in the United States. This doctoral research program attempted to study the root cause of the failure of pipes due to freezing and then propose a novel solution to overcome this undesirable occurrence. It was found that the freezing temperature of water is greatly dependent on the internal pressure of the pipe, which is itself dependent on pipe material, diameter, and thickness. Then, to mitigate the problems caused by ice formation and accumulation, a novel heating system was developed for usage in pipelines. The results suggest that the proposed novel heating system can be used on an industrial scale to mitigate the detrimental effects of ice accumulation in steel pipes. The third phase of this project was focused on developing a mathematical model that can predict the performance of the coating system by estimating the transient temperature of ice, the times that were required to heat and melt ice, and the transient location of the moving solid-liquid interface during the melting process. The results suggest that the mathematical models that were developed based on one-dimensional conduction in cylindrical coordinates can be employed to provide reasonable predictions of coating system performance up to maximum 16% and 9% relative difference between the experimental measurements and model predictions for ice heating and melting stages, respectively. The final phase of this project was on developing a techno-economic model to assess the feasibility of manufacturing and utilization of the coating-based heating systems. It was found that the total cost of fabrication of the coating system was about 7 times that of the tracers due mainly to the labor cost. However, the efficiency of the coating system was about 30% higher than conventional heat tracers. The results suggest that end-users must weigh the improved performance of the coatings against the increased fabrication and installation costs for large-scale protection of pipes against bursting in industrial applications.