An In-Depth Investigation into the Causes of the Performance Variations of Liquid-Applied Pipeline Coatings on Different Types of Abrasives Prepared Surfaces

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Dry abrasive blast cleaning is a commonly used surface preparation method to achieve the necessary surface cleanliness and roughness for the application of high-performance protective coatings. The effectiveness of abrasive blast cleaning depends on various factors, and some studies have indicated that the blasting abrasive used to clean the surface is crucial for the performance of the coating. The previous work evaluated the performances of two liquid-applied epoxy pipeline coatings (coating A and coating B) applied to 15 different surfaces.

Product Number: 51323-19561-SG

Author: Shan (Sherry) Rao

Publication Date: 2023

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The previous study revealed that the performances of two liquid-applied, 100% solids epoxy pipeline coatings (coating A and coating B) in immersion conditions are greatly influenced by the types of abrasives used to prepare the surfaces. A further investigation was conducted to better understand the results: (i) coating A performed superior on steel grit and shot abrasive prepared surfaces compared to coating B; (ii) coating A was more susceptible to blistering on surfaces prepared with coal slags; (iii) both coatings performed poorly on surfaces prepared with glass grits; (iv) surfaces prepared with mineral slag and mineral blends abrasives generally showed better performance than those prepared with other non-metallic abrasives.

A literature review was conducted to identify the mechanism of epoxy coatings to steel substrate adhesion, the effect of water interaction with epoxy, and detection techniques for the absorbed water. The levels of embedment on the blasted surfaces were re-assessed using an improved approach and the potential for blistering due to soluble salt contaminants in the abrasives was examined. Focuses were given in experimental examination to monitor change in water uptakes, corresponding change in glass transition (Tg) temperatures, and the status of coating/substrate interfacial conditions (retained adhesion and presence of corrosion under microscope) when the representative coated panels of the two coatings were subjected in hot water immersion at 75ºC. Subsequently, the results of these experiments led to possible explanations for the observed phenomena.