Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.
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Preventing T Corrosion under Insulation with Fiber-Reinforced Polymer Laminates he term "corrosion under insulation" (CUI) applies to a variety of electrochemical attacks on piping that is under thermal insulation. Since many commercial processes are thermally dependent, maintaining proper system temperatures is a direct cost as lost energy must be replaced. As energy costs rise, insulating systems become economically signifcant. Preventing CUI is driven by more than just reducing operating costs. Failure to control corrosion can lead to signifcant, catastrophic failure of piping systems. This causes possible risk to life of any nearby personnel as well as collateral damage to nearby equipment. If the damage is signifcant enough, extended plant shutdown for repair and investigation could also be involved. Establishing and maintaining a viable inspection program is essential. The Occupational Safety and Health Administration (OSHA) has codified requirements1 and the Clean Water Act2 has led to standards progressing from recommendations to requirements. To minimize the risk of catastrophic Larry Deaton, NRI, Lake Park, Florida failure, it is absolutely necessary that controls and preventative maintenance programs address CUI. This can be accomplished only by thoroughly understanding the mechanisms of CUI and then taking appropriate actions to prevent it. The basic mechanism for CUI involves repeated wetting and drying cycles of the associated insulation. Corrosion under insulation (CUI) of thermally protected pipelines can cause catastrophic failure of these systems. To minimize the risk of failure, it is necessary that corrosion prevention and maintenance programs address CUI. Te use of fber-reinforced polymer laminates is one way to efectively repair and protect piping from this type of corrosion. 74 MATERIALS PERFORMANCE May 2013 Mechanism of Corrosion under Insulation Moisture Generally, the piping insulation will become wet from environmental exposure, misting, proximity to cooling towers, or condensation during plant shutdowns. Moisture will penetrate the insulation in a liquid state when the pipNACE International, Vol. 52, No. 5