Damage Control: CUI Mitigation

The previous two articles of this three-part Damage Control series on corrosion under insulation (CUI) highlighted the challenges associated with detecting and properly evaluating this prevalent industry damage mechanism. This article focuses on practical steps to mitigate CUI damage on fixed pressure equipment. Proper initial design of insulation systems can dramatically reduce long-term reliability and maintenance issues associated with aqueous external corrosion on carbon and low-alloy steels. Furthermore, for in-service equipment, modifications to the existing insulation system and potentially the application of modern external coatings can improve overall damage tolerance going forward. To this end, taking appropriate steps to mitigate CUI can decrease the likelihood of costly equipment downtime that may be necessary to facilitate inspection, fitness-for-service assessments, repairs, or replacement. The intent of this article is to offer some perspective and commentary on common CUI mitigation techniques and good engineering practices for external insulation or fireproofing system design and application.