Internal Tank Coatings in Oil and Gas: Why Failures Persist in the Age of Advanced Coatings

Abstract Internal coatings for storage tanks are essential for protecting steel surfaces from aggressive service conditions in oil and gas operations. Despite the use of advanced coating systems such as 100% solids novolac epoxies, premature failures continue to occur, resulting in costly downtime, repairs, and environmental risks. This paper investigates the root causes of such failures based on field experience, laboratory testing, and failure analysis. Contributing factors include improper coating selection, inadequate surface preparation, and deviations from application specifications. A common issue is incorrect mixing ratio of base and hardener in multi-component coatings, leading to improper curing, soft or brittle films, intercoat disbondment, and inadequate chemical resistance. Thermal gradients caused by a hot internal medium and cooler external conditions or ambient temperature fluctuations can drive condensation and moisture entrapment, promoting osmotic blistering and corrosion beneath coatings that appear visually intact. Current qualification tests are also reviewed, revealing limitations in replicating service-induced stresses and environmental conditions. To improve coating performance, the paper recommends enhanced quality control during application, tighter integration between laboratory testing and field realities, and the use of more service-specific selection criteria. Ultimately, internal tank coatings, though a small capital item, play a critical role in asset integrity. A systems-based, proactive approach is essential for long-term operational reliability and sustainability